Import of z80 target

git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@455 42af7a65-404d-4744-a932-0658087f49c3

49 files changed, 5645 insertions, 0 deletions

diff --git a/nuttx/arch/z80/include/arch.h b/nuttx/arch/z80/include/arch.h
new file mode 100644
index 000000000..ff3a059e0
--- /dev/null
+++ b/nuttx/arch/z80/include/arch.h
@@ -0,0 +1,82 @@
+/****************************************************************************
+ * arch/arch.h
+ *
+ *   Copyright (C) 2007, 2008 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/* This file should never be included directed but, rather,
+ * only indirectly through nuttx/arch.h
+ */
+
+#ifndef __ARCH_ARCH_H
+#define __ARCH_ARCH_H
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <arch/chip/arch.h>
+
+/****************************************************************************
+ * Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Inline functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Types
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Variables
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Function Prototypes
+ ****************************************************************************/
+
+#ifdef __cplusplus
+#define EXTERN extern "C"
+extern "C" {
+#else
+#define EXTERN extern
+#endif
+
+#undef EXTERN
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* __ARCH_ARCH_H */
+
diff --git a/nuttx/arch/z80/include/irq.h b/nuttx/arch/z80/include/irq.h
new file mode 100644
index 000000000..6ef0188ac
--- /dev/null
+++ b/nuttx/arch/z80/include/irq.h
@@ -0,0 +1,81 @@
+/****************************************************************************
+ * arch/irq.h
+ *
+ *   Copyright (C) 2007, 2008 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/* This file should never be included directed but, rather,
+ * only indirectly through nuttx/irq.h
+ */
+
+#ifndef __ARCH_IRQ_H
+#define __ARCH_IRQ_H
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/irq.h>
+#include <arch/chip/irq.h>
+
+/****************************************************************************
+ * Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Types
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Variables
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Function Prototypes
+ ****************************************************************************/
+
+#ifndef __ASSEMBLY__
+#ifdef __cplusplus
+#define EXTERN extern "C"
+extern "C" {
+#else
+#define EXTERN extern
+#endif
+
+#undef EXTERN
+#ifdef __cplusplus
+}
+#endif
+#endif
+
+#endif /* __ARCH_IRQ_H */
+
diff --git a/nuttx/arch/z80/include/limits.h b/nuttx/arch/z80/include/limits.h
new file mode 100644
index 000000000..31a94a547
--- /dev/null
+++ b/nuttx/arch/z80/include/limits.h
@@ -0,0 +1,71 @@
+/****************************************************************************
+ * arch/limits.h
+ *
+ *   Copyright (C) 2007, 2008 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+#ifndef __ARCH_LIMITS_H
+#define __ARCH_LIMITS_H
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+/****************************************************************************
+ * Definitions
+ ****************************************************************************/
+
+#define CHAR_BIT        8
+#define SCHAR_MIN	0x80
+#define SCHAR_MAX	0x7f
+#define UCHAR_MAX	0xff
+
+/* These could be different on machines where char is unsigned */
+
+#define CHAR_MIN	SCHAR_MIN
+#define CHAR_MAX	SCHAR_MAX
+
+#define SHRT_MIN	0x8000
+#define SHRT_MAX	0x7fff
+#define USHRT_MAX	0xffff
+
+#define INT_MIN         0x8000
+#define INT_MAX         0x7fff
+#define UINT_MAX	0xffff
+
+/* These change on 32-bit and 64-bit platforms */
+
+#define LONG_MAX	0x80000000
+#define LONG_MIN	0x7fffffff
+#define ULONG_MAX	0xffffffff
+
+#endif /* __ARCH_LIMITS_H */
diff --git a/nuttx/arch/z80/include/serial.h b/nuttx/arch/z80/include/serial.h
new file mode 100644
index 000000000..dc3c4948b
--- /dev/null
+++ b/nuttx/arch/z80/include/serial.h
@@ -0,0 +1,61 @@
+/****************************************************************************
+ * arch/serial.h
+ *
+ *   Copyright (C) 2007, 2008 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+#ifndef __ARCH_SERIAL_H
+#define __ARCH_SERIAL_H
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+/****************************************************************************
+ * Definitions
+ ****************************************************************************/
+
+/* IOCTL commands supported by the z80 serial driver */
+
+#define TIOCSBRK        0x5401  /* BSD compatibility */
+#define TIOCCBRK        0x5402  /* " " "           " */
+#define TIOCSERGSTRUCT  0x5403  /* Get up_dev_t for port */
+
+/****************************************************************************
+ * Public Data
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+#endif /* __ARCH_SERIAL_H */
diff --git a/nuttx/arch/z80/include/types.h b/nuttx/arch/z80/include/types.h
new file mode 100644
index 000000000..d650e5a01
--- /dev/null
+++ b/nuttx/arch/z80/include/types.h
@@ -0,0 +1,87 @@
+/****************************************************************************
+ * arch/types.h
+ *
+ *   Copyright (C) 2007, 2008 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name Gregory Nutt nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/* This file should never be included directed but, rather,
+ * only indirectly through sys/types.h
+ */
+
+#ifndef __ARCH_TYPES_H
+#define __ARCH_TYPES_H
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+/****************************************************************************
+ * Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Type Declarations
+ ****************************************************************************/
+
+#ifndef __ASSEMBLY__
+
+/* These are the sizes of the standard SDCC types
+ *
+ * For SDCC, sizeof(int) is 16 and sizeof(long) is 32.
+ * long long and double are not supported.
+ *
+ * Generic pointers are 3 bytes in length with the the
+ * first byte holding data space intformation.
+ */
+
+typedef char sbyte;
+typedef unsigned char ubyte;
+typedef unsigned char uint8;
+typedef unsigned char boolean;
+typedef int sint16;
+typedef unsigned int uint16;
+typedef long sint32;
+typedef unsigned long uint32;
+
+/* This is the size of the interrupt state save returned by
+ * irqsave()
+ */
+
+typedef unsigned char irqstate_t;
+
+#endif /* __ASSEMBLY__ */
+
+/****************************************************************************
+ * Global Function Prototypes
+ ****************************************************************************/
+
+#endif /* __ARCH_TYPES_H */
diff --git a/nuttx/arch/z80/include/z80/arch.h b/nuttx/arch/z80/include/z80/arch.h
new file mode 100644
index 000000000..e9033596c
--- /dev/null
+++ b/nuttx/arch/z80/include/z80/arch.h
@@ -0,0 +1,77 @@
+/****************************************************************************
+ * arch/z80/arch.h
+ * arch/chip/arch.h
+ *
+ *   Copyright (C) 2007, 2008 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/* This file should never be included directed but, rather,
+ * only indirectly through nuttx/arch.h (via arch/arch.h)
+ */
+
+#ifndef __ARCH_Z80_ARCH_H
+#define __ARCH_Z80_ARCH_H
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+/****************************************************************************
+ * Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Types
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Variables
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Function Prototypes
+ ****************************************************************************/
+
+#ifdef __cplusplus
+#define EXTERN extern "C"
+extern "C" {
+#else
+#define EXTERN extern
+#endif
+
+#undef EXTERN
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* __ARCH_Z80_ARCH_H */
+
diff --git a/nuttx/arch/z80/include/z80/irq.h b/nuttx/arch/z80/include/z80/irq.h
new file mode 100644
index 000000000..c68dd76f9
--- /dev/null
+++ b/nuttx/arch/z80/include/z80/irq.h
@@ -0,0 +1,133 @@
+/****************************************************************************
+ * arch/z80/irq.h
+ * arch/chip/irq.h
+ *
+ *   Copyright (C) 2007, 2008 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/* This file should never be included directed but, rather,
+ * only indirectly through nuttx/irq.h (via arch/irq.h)
+ */
+
+#ifndef __ARCH_Z80_IRQ_H
+#define __ARCH_Z80_IRQ_H
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+/****************************************************************************
+ * Definitions
+ ****************************************************************************/
+
+/* Z80 Interrupts */
+
+#define Z80_IRQ_SYSTIMER (1)
+#define NR_IRQS          (1)
+
+/* IRQ Stack Frame Format
+ *
+ * This stack frame is created on each interrupt.  These registers are stored
+ * in the TCB to many context switches.
+ */
+
+#define XCPT_I               (0) /* Saved I w/interrupt state in carry */
+#define XCPT_AF              (1) /* Saved AF register */
+#define XCPT_BC              (2) /* Saved BC register */
+#define XCPT_DE              (3) /* Saved DE register */
+#define XCPT_HL              (4) /* Saved HL register */
+#define XCPT_IX              (5) /* Saved IX register */
+#define XCPT_IY              (6) /* Saved IY register */
+#define XCPT_SP              (7) /* Offset to SP at time of interrupt */
+#define XCPT_PC              (8) /* Offset to PC at time of interrupt */
+
+#define XCPTCONTEXT_REGS     (9)
+#define XCPTCONTEXT_SIZE     (2 * XCPTCONTEXT_REGS)
+
+/****************************************************************************
+ * Public Types
+ ****************************************************************************/
+
+/* This is the the type of the register save array */
+
+typedef uint16 chipreg_t;
+
+/* This struct defines the way the registers are stored. */
+
+#ifndef __ASSEMBLY__
+struct xcptcontext
+{
+  /* Register save area */
+
+  uint16 regs[XCPTCONTEXT_REGS];
+
+  /* The following function pointer is non-zero if there
+   * are pending signals to be processed.
+   */
+
+#ifndef CONFIG_DISABLE_SIGNALS
+  void *sigdeliver; /* Actual type is sig_deliver_t */
+#endif
+};
+#endif
+
+/****************************************************************************
+ * Inline functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Variables
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Function Prototypes
+ ****************************************************************************/
+
+#ifndef __ASSEMBLY__
+#ifdef __cplusplus
+#define EXTERN extern "C"
+extern "C" {
+#else
+#define EXTERN extern
+#endif
+
+EXTERN irqstate_t irqsave(void);
+EXTERN void       irqrestore(irqstate_t flags);
+
+#undef EXTERN
+#ifdef __cplusplus
+}
+#endif
+#endif
+
+#endif /* __ARCH_Z80_IRQ_H */
+
diff --git a/nuttx/arch/z80/src/Makefile b/nuttx/arch/z80/src/Makefile
new file mode 100644
index 000000000..0aabc09bb
--- /dev/null
+++ b/nuttx/arch/z80/src/Makefile
@@ -0,0 +1,220 @@
+############################################################################
+# arch/z80/src/Makefile
+#
+#   Copyright (C) 2007, 2008 Gregory Nutt. All rights reserved.
+#   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions
+# are met:
+#
+# 1. Redistributions of source code must retain the above copyright
+#    notice, this list of conditions and the following disclaimer.
+# 2. Redistributions in binary form must reproduce the above copyright
+#    notice, this list of conditions and the following disclaimer in
+#    the documentation and/or other materials provided with the
+#    distribution.
+# 3. Neither the name NuttX nor the names of its contributors may be
+#    used to endorse or promote products derived from this software
+#    without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+# FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+# COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+# INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+# BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+# OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+# AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+# ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+# POSSIBILITY OF SUCH DAMAGE.
+#
+############################################################################
+
+############################################################################
+# Makefile fragments
+
+-include $(TOPDIR)/Make.defs
+-include chip/Make.defs
+
+############################################################################
+# Tools
+
+MKDEP 		= $(TOPDIR)/tools/mkdeps.sh
+
+CFLAGS		+= -I$(ARCH_SRCDIR)/chip -I$(ARCH_SRCDIR)/common -I$(TOPDIR)/sched
+LDFLAGS		= $(ARCHSCRIPT)
+
+LDPATHES	= $(addprefix -L$(TOPDIR)/,$(dir $(LINKLIBS)))
+LDLIBS		= $(patsubst lib%,-l%,$(basename $(notdir $(LINKLIBS))))
+
+CPPFLAGS	= $(ARCHINCLUDES) $(ARCHDEFINES) -D__ASSEMBLY__
+
+############################################################################
+# Files and directories
+
+# There should be one head source (.asm file)
+
+HEAD_AOBJ	= $(HEAD_ASRC:$(ASMEXT)=$(OBJEXT))
+
+# Assembly sources and objects
+
+ASRCS		= $(CHIP_ASRCS) $(CMN_ASRCS)
+AOBJS		= $(ASRCS:.S=$(OBJEXT))
+
+# C sources and objects
+
+CSRCS		= $(CHIP_CSRCS) $(CMN_CSRCS)
+COBJS		= $(CSRCS:.c=$(OBJEXT))
+
+# All sources and objcts
+
+SRCS		= $(ASRCS) $(CSRCS)
+OBJS		= $(AOBJS) $(COBJS)
+
+# Sources and objects for the test target (plus HEAD_AOBJ
+
+TEST_AOBJS	= $(TEST_ASRCS:$(ASMEXT)=$(OBJEXT))
+TEST_COBJS	= $(TEST_CSRCS:.c=$(OBJEXT))
+
+TESTSRCS	= up_irqtest.c
+TESTOBJS	= $(TESTSRCS:.c=$(OBJEXT))
+TESTEXTRAOBJS	= up_savecontext$(OBJEXT) up_restorecontext$(OBJEXT)
+
+# Sources that can have dependencies (no .asm files)
+
+DEPSRCS		= $(SRCS)
+
+# Directories
+
+ARCH_SRCDIR	= $(TOPDIR)/arch/$(CONFIG_ARCH)/src
+BOARDDIR	= $(TOPDIR)/arch/$(CONFIG_ARCH)/src/board
+
+VPATH		= chip:common
+
+# Libraries
+
+LIBGCC		= ${shell $(CC) -print-libgcc-file-name}
+
+# Supports dynamic sizing of HEAP
+
+HEAP_BASE	= ${shell \
+			if [ -e pass1.mem ]; then \
+				cat pass1.mem | grep "ROM/EPROM/FLASH" | \
+				sed -e "s/[ ][ ]*/ /g" | cut -d' ' -f4 ; \
+			else \
+				echo $(DEF_HEAP_BASE) ; \
+			fi \
+		   }
+
+STACK_BASE	= ${shell \
+			if [ -e pass1.mem ]; then \
+				cat pass1.mem | grep "Stack starts" | \
+				cut -d' ' -f4 ; \
+			else \
+				echo $(DEF_STACK_BASE) ; \
+			fi \
+		   }
+
+############################################################################
+# Targets
+
+all: $(HEAD_AOBJ) libarch$(LIBEXT)
+
+$(AOBJS) $(HEAD_AOBJ) $(TEST_AOBJS): %$(OBJEXT): %$(ASMEXT)
+	$(AS) $(ASFLAGS) $@ $<
+
+$(COBJS) $(TEST_COBJS): %$(OBJEXT): %.c
+	$(CC) -c $(CFLAGS) $< -o $@
+
+# Create a header file that contains addressing information needed by the code
+
+pass1.mem:
+
+up_mem.h: pass1.mem
+	@echo "#ifndef __ARCH_MEM_H" >up_mem.h
+	@echo "#define __ARCH_MEM_H" >>up_mem.h
+	@echo "" >>up_mem.h
+	@echo "#define UP_DEFAULT_STACK_BASE $(DEF_STACK_BASE)" >>up_mem.h
+	@echo "#define UP_DEFAULT_HEAP_BASE $(DEF_HEAP_BASE)" >> up_mem.h
+	@echo "" >>up_mem.h
+	@echo "#define UP_STACK_BASE         $(STACK_BASE)" >>up_mem.h
+	@echo "#if UP_STACK_BASE > UP_DEFAULT_STACK_BASE" >>up_mem.h
+	@echo "#  error \"Stack overlap:  $(DEF_STACK_BASE) < $(STACK_BASE)\""  >>up_mem.h
+	@echo "#elif UP_STACK_BASE < UP_DEFAULT_STACK_BASE" >>up_mem.h
+	@echo "#  warning \"Wasted stack: $(DEF_STACK_BASE) > $(STACK_BASE)\""  >>up_mem.h
+	@echo "#endif" >>up_mem.h
+	@echo "" >>up_mem.h
+	@echo "#define UP_HEAP_BASE          $(HEAP_BASE)" >> up_mem.h
+	@echo "#define UP_HEAP_END           $(CONFIG_DRAM_END)" >> up_mem.h
+	@echo "" >>up_mem.h
+	@echo "#endif /* __ARCH_MEM_H */" >>up_mem.h
+
+# Combine all objects in this directory into a library
+
+libarch$(LIBEXT): up_mem.h $(OBJS)
+	@( for obj in $(OBJS) ; do \
+		$(AR) $@ $${obj} || \
+			{ echo "$(AR) $@ $${obj} FAILED!" ; exit 1 ; } ; \
+	done ; )
+
+# This builds the libboard library in the board/ subdirectory 
+
+board/libboard$(LIBEXT):
+	$(MAKE) -C board TOPDIR=$(TOPDIR) libboard$(LIBEXT)
+
+# This target builds the final executable
+
+pass1.ihx: up_mem.h $(HEAD_AOBJ) board/libboard$(LIBEXT)
+	$(CC) $(LDFLAGS) -L$(BOARDDIR) $(SDCCPATH) $(HEAD_AOBJ) \
+		-llibboard$(LIBEXT) $(SDCCLIBS) -o $@
+	@rm -f up_mem.h
+	@rm -f up_allocateheap$(OBJEXT) libarch$(LIBEXT)
+	@$(MAKE) TOPDIR=$(TOPDIR) libarch$(LIBEXT)
+
+nuttx.ihx: up_mem.h $(HEAD_AOBJ)
+	$(CC) $(LDFLAGS) -L$(BOARDDIR) $(SDCCPATH) $(HEAD_AOBJ) \
+		-llibboard$(LIBEXT) $(SDCCLIBS) -o $@
+
+nuttx$(EXEEXT): pass1.ihx nuttx.ihx
+	@rm -f pass1.*
+	packihx nuttx.ihx > $(TOPDIR)/nuttx$(EXEEXT)
+	@cp -f nuttx.map $(TOPDIR)/.
+
+# This target builds a test program to verify interrupt context switching.  irqtest is
+# a PHONY target that just sets upt the up_irqtest build correctly
+
+up_irqtest.ihx: $(TEST_COBJS)
+	$(CC) $(LDFLAGS) -L. $(SDCCPATH) $(HEAD_AOBJ) $(TEST_COBJS) $(TESTEXTRAOBJS) $(SDCCLIBS) -o $@
+
+irqtest:
+	$(MAKE) TOPDIR=../../.. up_irqtest.ihx
+
+# Build dependencies
+
+.depend: Makefile up_mem.h chip/Make.defs $(DEPSRCS)
+	@if [ -e board/Makefile ]; then \
+		$(MAKE) -C board TOPDIR=$(TOPDIR) depend ; \
+	fi
+	$(MKDEP) --dep-path chip --dep-path common $(CC) -- $(CFLAGS) -- $(SRCS) >Make.dep
+	@touch $@
+
+depend: .depend
+
+clean:
+	@if [ -e board/Makefile ]; then \
+		$(MAKE) -C board TOPDIR=$(TOPDIR) clean ; \
+	fi
+	rm -f libarch$(LIBEXT) up_mem.h
+	rm -f *.asm *.rel *.lst *.rst *.sym *.adb *.lnk *.map *.mem *.ihx *.hex *~
+	if [ ! -z "$(OBJEXT)" ]; then rm -f *$(OBJEXT); fi
+
+distclean: clean
+	@if [ -e board/Makefile ]; then \
+		$(MAKE) -C board TOPDIR=$(TOPDIR) distclean ; \
+	fi
+	rm -f Make.dep .depend
+
+-include Make.dep
diff --git a/nuttx/arch/z80/src/common/up_allocateheap.c b/nuttx/arch/z80/src/common/up_allocateheap.c
new file mode 100644
index 000000000..04e5f2d99
--- /dev/null
+++ b/nuttx/arch/z80/src/common/up_allocateheap.c
@@ -0,0 +1,79 @@
+/****************************************************************************
+ * common/up_allocateheap.c
+ *
+ *   Copyright (C) 2007, 2008 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+#include <sys/types.h>
+#include <debug.h>
+#include <nuttx/arch.h>
+#include "up_arch.h"
+#include "up_internal.h"
+
+/****************************************************************************
+ * Private Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: up_allocate_heap
+ *
+ * Description:
+ *   The heap may be statically allocated by
+ *   defining CONFIG_HEAP_BASE and CONFIG_HEAP_SIZE.  If these
+ *   are not defined, then this function will be called to
+ *   dynamically set aside the heap region.
+ *
+ ****************************************************************************/
+
+void up_allocate_heap(FAR void **heap_start, size_t *heap_size)
+{
+  up_ledon(LED_HEAPALLOCATE);
+  *heap_start = (void*)(CONFIG_DRAM_SIZE - CONFIG_HEAP_SIZE);
+  *heap_size  = CONFIG_HEAP_SIZE;
+}
diff --git a/nuttx/arch/z80/src/common/up_arch.h b/nuttx/arch/z80/src/common/up_arch.h
new file mode 100644
index 000000000..b0158325a
--- /dev/null
+++ b/nuttx/arch/z80/src/common/up_arch.h
@@ -0,0 +1,70 @@
+/************************************************************************************
+ * common/up_arch.h
+ *
+ *   Copyright (C) 2007 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name Gregory Nutt nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ************************************************************************************/
+
+#ifndef __UP_ARCH_H
+#define __UP_ARCH_H
+
+/************************************************************************************
+ * Included Files
+ ************************************************************************************/
+
+#include <nuttx/config.h>
+#ifndef __ASSEMBLY__
+# include <sys/types.h>
+#endif
+
+#include <arch/board/board.h>
+#include "chip.h"
+
+/************************************************************************************
+ * Definitions
+ ************************************************************************************/
+
+/************************************************************************************
+ * Inline Functions
+ ************************************************************************************/
+
+#ifndef __ASSEMBLY__
+
+# define getreg8(a)           (*(volatile ubyte *)(a))
+# define putreg8(v,a)         (*(volatile ubyte *)(a) = (v))
+# define getreg32(a)          (*(volatile uint32 *)(a))
+# define putreg32(v,a)        (*(volatile uint32 *)(a) = (v))
+# define getreg(a)   getreg16(1)
+# define putreg(v,a) putreg16(v,a)
+
+#endif
+
+#endif  /* __UP_ARCH_H */
diff --git a/nuttx/arch/z80/src/common/up_assert.c b/nuttx/arch/z80/src/common/up_assert.c
new file mode 100644
index 000000000..f226c9431
--- /dev/null
+++ b/nuttx/arch/z80/src/common/up_assert.c
@@ -0,0 +1,156 @@
+/****************************************************************************
+ * common/up_assert.c
+ *
+ *   Copyright (C) 2007, 2008 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <sys/types.h>
+#include <stdlib.h>
+#include <assert.h>
+#include <debug.h>
+
+#include <nuttx/irq.h>
+#include <nuttx/arch.h>
+#include <chip/chip.h>
+
+#include "up_arch.h"
+#include "os_internal.h"
+#include "up_internal.h"
+#include "up_mem.h"
+
+/****************************************************************************
+ * Definitions
+ ****************************************************************************/
+
+/* Output debug info if stack dump is selected -- even if 
+ * debug is not selected.
+ */
+
+#ifdef CONFIG_ARCH_STACKDUMP
+# undef  lldbg
+# define lldbg lib_lowprintf
+#endif
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: _up_assert
+ ****************************************************************************/
+
+static void _up_assert(int errorcode) /* __attribute__ ((noreturn)) */
+{
+  /* Are we in an interrupt handler or the idle task? */
+
+  if (up_interrupt_context() || ((FAR _TCB*)g_readytorun.head)->pid == 0)
+    {
+       (void)irqsave();
+        for(;;)
+          {
+#ifdef CONFIG_ARCH_LEDS
+            up_ledon(LED_PANIC);
+            up_mdelay(250);
+            up_ledoff(LED_PANIC);
+            up_mdelay(250);
+#endif
+          }
+    }
+  else
+    {
+      exit(errorcode);
+    }
+}
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: up_assert
+ ****************************************************************************/
+
+void up_assert(const ubyte *filename, int lineno)
+{
+#if CONFIG_TASK_NAME_SIZE > 0
+  _TCB *rtcb = (_TCB*)g_readytorun.head;
+#endif
+
+  up_ledon(LED_ASSERTION);
+
+#if CONFIG_TASK_NAME_SIZE > 0
+  lldbg("Assertion failed at file:%s line: %d task: %s\n",
+        filename, lineno, rtcb->name);
+#else
+  lldbg("Assertion failed at file:%s line: %d\n",
+        filename, lineno);
+#endif
+
+  up_stackdump();
+  up_registerdump();
+ _up_assert(EXIT_FAILURE);
+}
+
+/****************************************************************************
+ * Name: up_assert_code
+ ****************************************************************************/
+
+void up_assert_code(const ubyte *filename, int lineno, int errorcode)
+{
+#if CONFIG_TASK_NAME_SIZE > 0
+  _TCB *rtcb = (_TCB*)g_readytorun.head;
+#endif
+
+  up_ledon(LED_ASSERTION);
+
+#if CONFIG_TASK_NAME_SIZE > 0
+  lldbg("Assertion failed at file:%s line: %d task: %s error code: %d\n",
+        filename, lineno, rtcb->name, errorcode);
+#else
+  lldbg("Assertion failed at file:%s line: %d error code: %d\n",
+        filename, lineno, errorcode);
+#endif
+
+  up_stackdump();
+  up_registerdump();
+ _up_assert(errorcode);
+}
diff --git a/nuttx/arch/z80/src/common/up_blocktask.c b/nuttx/arch/z80/src/common/up_blocktask.c
new file mode 100644
index 000000000..b2d014bca
--- /dev/null
+++ b/nuttx/arch/z80/src/common/up_blocktask.c
@@ -0,0 +1,173 @@
+/****************************************************************************
+ * common/up_blocktask.c
+ *
+ *   Copyright (C) 2007, 2008 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <sys/types.h>
+#include <sched.h>
+#include <debug.h>
+
+#include <nuttx/arch.h>
+
+#include "os_internal.h"
+#include "up_internal.h"
+
+/****************************************************************************
+ * Private Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Funtions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Funtions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: up_block_task
+ *
+ * Description:
+ *   The currently executing task at the head of
+ *   the ready to run list must be stopped.  Save its context
+ *   and move it to the inactive list specified by task_state.
+ *
+ * Inputs:
+ *   tcb: Refers to a task in the ready-to-run list (normally
+ *     the task at the the head of the list).  It most be
+ *     stopped, its context saved and moved into one of the
+ *     waiting task lists.  It it was the task at the head
+ *     of the ready-to-run list, then a context to the new
+ *     ready to run task must be performed.
+ *   task_state: Specifies which waiting task list should be
+ *     hold the blocked task TCB.
+ *
+ ****************************************************************************/
+
+void up_block_task(FAR _TCB *tcb, tstate_t task_state)
+{
+  /* Verify that the context switch can be performed */
+
+  if ((tcb->task_state < FIRST_READY_TO_RUN_STATE) ||
+      (tcb->task_state > LAST_READY_TO_RUN_STATE))
+    {
+      PANIC(OSERR_BADBLOCKSTATE);
+    }
+  else
+    {
+      FAR _TCB *rtcb = (FAR _TCB*)g_readytorun.head;
+      boolean switch_needed;
+
+      /* dbg("Blocking TCB=%p\n", tcb); */
+
+      /* Remove the tcb task from the ready-to-run list.  If we
+       * are blocking the task at the head of the task list (the
+       * most likely case), then a context switch to the next
+       * ready-to-run task is needed. In this case, it should
+       * also be true that rtcb == tcb.
+       */
+
+      switch_needed = sched_removereadytorun(tcb);
+
+      /* Add the task to the specified blocked task list */
+
+      sched_addblocked(tcb, (tstate_t)task_state);
+
+      /* If there are any pending tasks, then add them to the g_readytorun
+       * task list now
+       */
+
+      if (g_pendingtasks.head)
+        {
+          switch_needed |= sched_mergepending();
+        }
+
+      /* Now, perform the context switch if one is needed */
+
+      if (switch_needed)
+        {
+          /* Are we in an interrupt handler? */
+
+          if (IN_INTERRUPT)
+            {
+              /* Yes, then we have to do things differently.
+               * Just copy the current registers into the OLD rtcb.
+               */
+
+               SAVE_IRQCONTEXT(rtcb);
+
+              /* Restore the exception context of the rtcb at the (new) head 
+               * of the g_readytorun task list.
+               */
+
+              rtcb = (FAR _TCB*)g_readytorun.head;
+              /* dbg("New Active Task TCB=%p\n", rtcb); */
+
+              /* Then setup so that the context will be performed on exit
+               * from the interrupt.
+               */
+
+              SET_IRQCONTEXT(rtcb);
+            }
+
+          /* Copy the user C context into the TCB at the (old) head of the
+           * g_readytorun Task list. if SAVE_USERCONTEXT returns a non-zero
+           * value, then this is really the previously running task restarting!
+           */
+
+          else if (!SAVE_USERCONTEXT(rtcb))
+            {
+              /* Restore the exception context of the rtcb at the (new) head 
+               * of the g_readytorun task list.
+               */
+
+              rtcb = (FAR _TCB*)g_readytorun.head;
+              /* dbg("New Active Task TCB=%p\n", rtcb); */
+
+              /* Then switch contexts */
+
+              RESTORE_USERCONTEXT(rtcb);
+            }
+        }
+    }
+}
diff --git a/nuttx/arch/z80/src/common/up_copystate.c b/nuttx/arch/z80/src/common/up_copystate.c
new file mode 100644
index 000000000..8a4915181
--- /dev/null
+++ b/nuttx/arch/z80/src/common/up_copystate.c
@@ -0,0 +1,78 @@
+/****************************************************************************
+ * common/up_copystate.c
+ *
+ *   Copyright (C) 2007, 2008 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <sys/types.h>
+#include <arch/irq.h>
+
+#include "os_internal.h"
+#include "up_internal.h"
+
+/****************************************************************************
+ * Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Funtions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: up_undefinedinsn
+ ****************************************************************************/
+
+/* Maybe a little faster than most memcpy's */
+
+void up_copystate(FAR chipreg_t *dest, FAR const chipreg_t *src)
+{
+  int i;
+  for (i = 0; i < XCPTCONTEXT_REGS; i++)
+    {
+      *dest++ = *src++;
+    }
+}
+
diff --git a/nuttx/arch/z80/src/common/up_createstack.c b/nuttx/arch/z80/src/common/up_createstack.c
new file mode 100644
index 000000000..dc3f715c9
--- /dev/null
+++ b/nuttx/arch/z80/src/common/up_createstack.c
@@ -0,0 +1,128 @@
+/****************************************************************************
+ * common/up_createstack.c
+ *
+ *   Copyright (C) 2007, 2008 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+#include <sys/types.h>
+#include <sched.h>
+#include <debug.h>
+#include <nuttx/kmalloc.h>
+#include <nuttx/arch.h>
+#include "up_arch.h"
+#include "up_internal.h"
+
+/****************************************************************************
+ * Private Types
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Function Prototypes
+ ****************************************************************************/
+
+/****************************************************************************
+ * Global Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: up_create_stack
+ *
+ * Description:
+ *   Allocate a stack for a new thread and setup
+ *   up stack-related information in the TCB.
+ *
+ *   The following TCB fields must be initialized:
+ *   adj_stack_size: Stack size after adjustment for hardware,
+ *     processor, etc.  This value is retained only for debug
+ *     purposes.
+ *   stack_alloc_ptr: Pointer to allocated stack
+ *   adj_stack_ptr: Adjusted stack_alloc_ptr for HW.  The
+ *     initial value of the stack pointer.
+ *
+ * Inputs:
+ *   tcb: The TCB of new task
+ *   stack_size:  The requested stack size.  At least this much
+ *     must be allocated.
+ ****************************************************************************/
+
+STATUS up_create_stack(_TCB *tcb, size_t stack_size)
+{
+  if (tcb->stack_alloc_ptr &&
+      tcb->adj_stack_size != stack_size)
+    {
+      sched_free(tcb->stack_alloc_ptr);
+      tcb->stack_alloc_ptr = NULL;
+    }
+
+   if (!tcb->stack_alloc_ptr)
+     {
+       tcb->stack_alloc_ptr = (uint32 *)kzmalloc(stack_size);
+     }
+
+   if (tcb->stack_alloc_ptr)
+     {
+       size_t top_of_stack;
+       size_t size_of_stack;
+
+       /* The Arm7Tdmi uses a push-down stack:  the stack grows
+	* toward loweraddresses in memory.  The stack pointer
+	* register, points to the lowest, valid work address
+	* (the "top" of the stack).  Items on the stack are
+	* referenced as positive word offsets from sp.
+	*/
+
+       top_of_stack = (uint32)tcb->stack_alloc_ptr + stack_size - 4;
+
+       /* The Arm7Tdmi stack must be aligned at word (4 byte)
+	* boundaries. If necessary top_of_stack must be rounded
+	* down to the next boundary
+	*/
+
+       top_of_stack &= ~3;
+       size_of_stack = top_of_stack - (uint32)tcb->stack_alloc_ptr + 4;
+
+       /* Save the adjusted stack values in the _TCB */
+
+       tcb->adj_stack_ptr  = (uint32*)top_of_stack;
+       tcb->adj_stack_size = size_of_stack;
+
+       up_ledon(LED_STACKCREATED);
+       return OK;
+     }
+
+   return ERROR;
+}
diff --git a/nuttx/arch/z80/src/common/up_doirq.c b/nuttx/arch/z80/src/common/up_doirq.c
new file mode 100644
index 000000000..d21cefabb
--- /dev/null
+++ b/nuttx/arch/z80/src/common/up_doirq.c
@@ -0,0 +1,104 @@
+/****************************************************************************
+ * common/up_doirq.c
+ *
+ *   Copyright (C) 2007, 2008 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+#include <sys/types.h>
+#include <nuttx/irq.h>
+#include <nuttx/arch.h>
+#include <assert.h>
+#include "up_arch.h"
+#include "os_internal.h"
+#include "up_internal.h"
+
+/****************************************************************************
+ * Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Data
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Funtions
+ ****************************************************************************/
+
+void up_doirq(int irq, chipreg_t *regs)
+{
+  up_ledon(LED_INIRQ);
+#ifdef CONFIG_SUPPRESS_INTERRUPTS
+  PANIC(OSERR_ERREXCEPTION);
+#else
+  if ((unsigned)irq < NR_IRQS)
+    {
+       /* Current regs non-zero indicates that we are processing
+        * an interrupt; current_regs is also used to manage
+        * interrupt level context switches.
+        */
+
+       current_regs = regs;
+
+       /* Mask and acknowledge the interrupt */
+
+       up_maskack_irq(irq);
+
+       /* Deliver the IRQ */
+
+       irq_dispatch(irq, regs);
+
+       /* Indicate that we are no long in an interrupt handler */
+
+       current_regs = NULL;
+
+       /* Unmask the last interrupt (global interrupts are still
+        * disabled.
+        */
+
+       up_enable_irq(irq);
+    }
+  up_ledoff(LED_INIRQ);
+#endif
+}
diff --git a/nuttx/arch/z80/src/common/up_exit.c b/nuttx/arch/z80/src/common/up_exit.c
new file mode 100644
index 000000000..8784f2f78
--- /dev/null
+++ b/nuttx/arch/z80/src/common/up_exit.c
@@ -0,0 +1,200 @@
+/****************************************************************************
+ * common/up_exit.c
+ *
+ *   Copyright (C) 2007, 2008 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <sys/types.h>
+#include <sched.h>
+#include <debug.h>
+
+#include <nuttx/arch.h>
+#include <chip/chip.h>
+
+#include "os_internal.h"
+#include "up_internal.h"
+
+#ifdef CONFIG_DUMP_ON_EXIT
+#include <nuttx/fs.h>
+#endif
+
+/****************************************************************************
+ * Private Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Funtions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: _up_dumponexit
+ *
+ * Description:
+ *   Dump the state of all tasks whenever on task exits.  This
+ *   is debug instrumentation that was added to check file-
+ *   related reference counting but could be useful again
+ *   sometime in the future.
+ *
+ ****************************************************************************/
+
+#if defined(CONFIG_DUMP_ON_EXIT) && defined(CONFIG_DEBUG)
+static void _up_dumponexit(FAR _TCB *tcb, FAR void *arg)
+{
+#if CONFIG_NFILE_DESCRIPTORS > 0 || CONFIG_NFILE_STREAMS > 0
+  int i;
+#endif
+
+  dbg("  TCB=%p name=%s\n", tcb, tcb->argv[0]);
+
+#if CONFIG_NFILE_DESCRIPTORS > 0
+  if (tcb->filelist)
+    {
+      lldbg("    filelist refcount=%d\n",
+            tcb->filelist->fl_crefs);
+
+      for (i = 0; i < CONFIG_NFILE_DESCRIPTORS; i++)
+        {
+          struct inode *inode = tcb->filelist->fl_files[i].f_inode;
+          if (inode)
+            {
+              lldbg("      fd=%d refcount=%d\n",
+                    i, inode->i_crefs);
+            }
+        }
+    }
+#endif
+
+#if CONFIG_NFILE_STREAMS > 0
+  if (tcb->streams)
+    {
+      lldbg("    streamlist refcount=%d\n",
+            tcb->streams->sl_crefs);
+
+      for (i = 0; i < CONFIG_NFILE_STREAMS; i++)
+        {
+          struct file_struct *filep = &tcb->streams->sl_streams[i];
+          if (filep->fs_filedes >= 0)
+            {
+              lldbg("      fd=%d nbytes=%d\n",
+                    filep->fs_filedes,
+                    filep->fs_bufpos - filep->fs_bufstart);
+            }
+        }
+    }
+#endif
+}
+#endif
+
+/****************************************************************************
+ * Public Funtions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: _exit
+ *
+ * Description:
+ *   This function causes the currently executing task to cease
+ *   to exist.  This is a special case of task_delete().
+ *
+ ****************************************************************************/
+
+void _exit(int status)
+{
+  FAR _TCB* tcb = (FAR _TCB*)g_readytorun.head;
+
+  /* Disable interrupts.  Interrupts will remain disabled until
+   * the new task is resumed below.
+   */
+
+  (void)irqsave();
+
+  lldbg("TCB=%p exitting\n", tcb);
+
+#if defined(CONFIG_DUMP_ON_EXIT) && defined(CONFIG_DEBUG)
+  lldbg("Other tasks:\n");
+  sched_foreach(_up_dumponexit, NULL);
+#endif
+
+  /* Remove the tcb task from the ready-to-run list.  We can
+   * ignore the return value because we know that a context
+   * switch is needed.
+   */
+
+  (void)sched_removereadytorun(tcb);
+
+  /* We are not in a bad stack-- the head of the ready to run task list
+   * does not correspond to the thread that is running.  Disabling pre-
+   * emption on this TCB should be enough to keep things stable.
+   */
+
+  sched_lock();
+
+  /* Move the TCB to the specified blocked task list and delete it */
+
+  sched_addblocked(tcb, TSTATE_TASK_INACTIVE);
+  task_delete(tcb->pid);
+
+  /* If there are any pending tasks, then add them to the g_readytorun
+   * task list now
+   */
+
+  if (g_pendingtasks.head)
+    {
+      (void)sched_mergepending();
+    }
+
+  /* Now calling sched_unlock() should have no effect */
+
+  sched_unlock();
+
+  /* Now, perform the context switch to the new ready-to-run task at the
+   * head of the list.
+   */
+
+  tcb = (FAR _TCB*)g_readytorun.head;
+  lldbg("New Active Task TCB=%p\n", tcb);
+
+  /* Then switch contexts */
+
+  RESTORE_USERCONTEXT(tcb);
+}
+
diff --git a/nuttx/arch/z80/src/common/up_head.asm b/nuttx/arch/z80/src/common/up_head.asm
new file mode 100644
index 000000000..272754e05
--- /dev/null
+++ b/nuttx/arch/z80/src/common/up_head.asm
@@ -0,0 +1,157 @@
+;**************************************************************************

+; arch/z80/src/common/up_head.S

+;

+;   Copyright (C) 2007, 2008 Gregory Nutt. All rights reserved.

+;   Author: Gregory Nutt <spudmonkey@racsa.co.cr>

+;

+; Redistribution and use in source and binary forms, with or without

+; modification, are permitted provided that the following conditions

+; are met:

+;

+; 1. Redistributions of source code must retain the above copyright

+;    notice, this list of conditions and the following disclaimer.

+; 2. Redistributions in binary form must reproduce the above copyright

+;    notice, this list of conditions and the following disclaimer in

+;    the documentation and/or other materials provided with the

+;    distribution.

+; 3. Neither the name NuttX nor the names of its contributors may be

+;    used to endorse or promote products derived from this software

+;    without specific prior written permission.

+;

+; THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS

+; "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT

+; LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS

+; FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE

+; COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,

+; INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,

+; BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS

+; OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED

+; AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT

+; LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN

+; ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE

+; POSSIBILITY OF SUCH DAMAGE.

+;

+;**************************************************************************

+

+	.title	NuttX for the Z80

+	.module	z80_head

+

+;**************************************************************************

+; Constants

+;**************************************************************************

+

+	; Register save area layout

+

+	XCPT_PC	==  0		; Offset to PC at time of interrupt

+	XCPT_AF	==  2		; Saved AF register

+	XCPT_HL	==  4		; Saved HL register

+	XCPT_SP	==  6		; Offset to SP at time of interrupt

+	XCPT_IY	==  8		; Saved IY register

+	XCPT_IX	== 10		; Saved IX register

+	XCPT_DE	== 12		; Saved DE register

+	XCPT_BC	== 14		; Saved BC register

+	XCPT_I 	== 16		; Saved I w/interrupt state in carry

+

+;**************************************************************************

+; Global symbols used

+;**************************************************************************

+

+	.globl	_os_start		; OS entry point

+	.globl	_idle_stack		; Top of allocated stack region

+	.globl	_up_irqdecode		; Interrupt decoding logic

+

+;**************************************************************************

+; Reset entry point

+;**************************************************************************

+

+	.area	TEXT	(ABS,OVR)

+	.org	0x0000

+

+	.globl	_os_start

+	di				 ; Disable interrupts

+	ld	SP, #_idle_stack	 ; Set stack pointer

+	im	1			 ; Set interrupt mode 1

+	jp	_os_start		 ; jump to the OS entry point

+forever:

+	jp	forever

+

+;**************************************************************************

+; Interrupt handler

+;

+; Interrupt mode 1 behavior:

+; 

+; 1. M1 cycle: 7 ticks

+;    Acknowledge interrupt and decrements SP

+; 2. M2 cycle: 3 ticks

+;    Writes the MS byte of the PC onto the stack and decrements SP

+; 3. M3 cycle: 3 ticks

+;    Writes the LS byte of the PC onto the stack and sets the PC to 0x0038.

+;

+;**************************************************************************

+

+	.org   0x0038			; Int mode 1

+

+	; Create a register frame.  SP points to top of frame + 2, pushes

+	; decrement the stack pointer.

+					; Offset 8: Return PC is already on the stack

+	push	af			; Offset 7: AF (retaining flags)

+	push	hl			; Offset 6: HL

+	ld	hl, #-(3*2)		;    HL is the value of the stack pointer before

+	add	hl, sp			;    the interrupt occurred

+	push	hl			; Offset 5: Stack pointer

+	push	iy			; Offset 4: IY

+	push	ix			; Offset 3: IX

+	push	de			; Offset 2: DE

+	push	bc			; Offset 1: BC

+

+	ld	a, i			;   Carry bit holds interrupt state

+	push	af			; Offset 0: I with interrupt state in carry

+	di

+

+	 ; Call the interrupt decode logic

+					; SP points to the beggining of the reg structure

+	ld	hl, #0			; Argument is the beginning of the reg structure

+	add	hl, sp

+	push	hl

+	call	_up_irqdecode		; Decode the IRQ

+

+	; Restore registers.  HL points to the beginning of the reg structure to restore

+

+	ld	sp, hl			; Use the temp stack pointer

+	ex	af, af'			; Select alternate AF

+	pop	af			; Offset 0: AF' = I with interrupt state in carry

+	pop	bc			; Offset 1: BC

+	pop	de			; Offset 2: DE

+	pop	ix			; Offset 3: IX

+	pop	iy			; Offset 4: IY

+	exx				;   Use alternate BC/DE/HL

+	pop	hl			; Offset 5: HL' = Stack pointer at time of interrupt

+	exx

+	pop	hl			; Offset 6: HL

+	pop	af			; Offset 7: AF

+

+	; Restore the stack pointer

+

+	exx

+	ld	sp, hl

+	exx

+

+	; Restore interrupt state

+

+	ex	af, af'			; Recover interrupt state

+	jr	nc, nointenable		; No carry, IFF2=0, means disabled

+	ex	af, af'			; Restore AF (before enabling interrupts)

+	ei				; yes

+	reti

+nointenable:

+	ex	af, af'			; Restore AF

+	reti

+

+;**************************************************************************

+; NMI interrupt handler

+;**************************************************************************

+

+	.org   0x0066

+	retn

+

+

diff --git a/nuttx/arch/z80/src/common/up_idle.c b/nuttx/arch/z80/src/common/up_idle.c
new file mode 100644
index 000000000..e2fb1e00f
--- /dev/null
+++ b/nuttx/arch/z80/src/common/up_idle.c
@@ -0,0 +1,107 @@
+/****************************************************************************
+ * common/up_idle.c
+ *
+ *   Copyright (C) 2007, 2008 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <sys/types.h>
+
+#include <nuttx/arch.h>
+#include <arch/board/board.h>
+
+#include "up_internal.h"
+
+/****************************************************************************
+ * Private Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+#if defined(CONFIG_ARCH_LEDS) && defined(CONFIG_ARCH_BRINGUP)
+static ubyte g_ledtoggle = 0;
+#endif
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: up_idle
+ *
+ * Description:
+ *   up_idle() is the logic that will be executed when their
+ *   is no other ready-to-run task.  This is processor idle
+ *   time and will continue until some interrupt occurs to
+ *   cause a context switch from the idle task.
+ *
+ *   Processing in this state may be processor-specific. e.g.,
+ *   this is where power management operations might be
+ *   performed.
+ *
+ ****************************************************************************/
+
+void up_idle(void)
+{
+#if defined(CONFIG_ARCH_LEDS) && defined(CONFIG_ARCH_BRINGUP)
+  g_ledtoggle++;
+  if (g_ledtoggle == 0x80)
+    {
+      up_ledon(LED_IDLE);
+    }
+  else if (g_ledtoggle == 0x00)
+    {
+      up_ledoff(LED_IDLE);
+    }
+#endif
+
+#if defined(CONFIG_SUPPRESS_INTERRUPTS) || defined(CONFIG_SUPPRESS_TIMER_INTS)
+  /* If the system is idle and there are no timer interrupts,
+   * then process "fake" timer interrupts. Hopefully, something
+   * will wake up.
+   */
+
+  sched_process_timer();
+#endif
+}
+
diff --git a/nuttx/arch/z80/src/common/up_initialize.c b/nuttx/arch/z80/src/common/up_initialize.c
new file mode 100644
index 000000000..a24d814dc
--- /dev/null
+++ b/nuttx/arch/z80/src/common/up_initialize.c
@@ -0,0 +1,158 @@
+/****************************************************************************
+ * common/up_initialize.c
+ *
+ *   Copyright (C) 2007, 2008 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <sys/types.h>
+#include <debug.h>
+
+#include <nuttx/arch.h>
+#include <nuttx/fs.h>
+#include <nuttx/mm.h>
+#include <arch/board/board.h>
+
+#include "up_internal.h"
+
+/****************************************************************************
+ * Definitions
+ ****************************************************************************/
+
+/* Define to enable timing loop calibration */
+
+#undef CONFIG_ARCH_CALIBRATION
+
+/****************************************************************************
+ * Private Types
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: up_calibratedelay
+ *
+ * Description:
+ *   Delay loops are provided for short timing loops.  This function, if
+ *   enabled, will just wait for 100 seconds.  Using a stopwatch, you can
+ *   can then determine if the timing loops are properly calibrated.
+ *
+ ****************************************************************************/
+
+#if defined(CONFIG_ARCH_CALIBRATION) & defined(CONFIG_DEBUG)
+static void up_calibratedelay(void)
+{
+  int i;
+  lldbg("Beginning 100s delay\n");
+  for (i = 0; i < 100; i++)
+    {
+      up_mdelay(1000);
+    }
+  lldbg("End 100s delay\n");
+}
+#else
+# define up_calibratedelay()
+#endif
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: up_initialize
+ *
+ * Description:
+ *   up_initialize will be called once during OS initialization after the
+ *   basic OS services have been initialized.  The architecture specific
+ *   details of initializing the OS will be handled here.  Such things as
+ *   setting up interrupt service routines, starting the clock, and
+ *   registering device drivers are some of the things that are different
+ *   for each processor and hardware platform.
+ *
+ *   up_initialize is called after the OS initialized but before the user
+ *   initialization logic has been started and before the libraries have
+ *   been initialized.  OS services and driver services are available.
+ *
+ ****************************************************************************/
+
+void up_initialize(void)
+{
+  /* Initialize global variables */
+
+  current_regs = NULL;
+
+  /* Calibrate the timing loop */
+
+  up_calibratedelay();
+
+  /* Add extra memory fragments to the memory manager */
+
+#if CONFIG_MM_REGIONS > 1
+  up_addregion();
+#endif
+
+  /* Initialize the interrupt subsystem */
+
+  up_irqinitialize();
+
+  /* Initialize the system timer interrupt */
+
+#if !defined(CONFIG_SUPPRESS_INTERRUPTS) && !defined(CONFIG_SUPPRESS_TIMER_INTS)
+  up_timerinit();
+#endif
+
+  /* Register devices */
+
+#if CONFIG_NFILE_DESCRIPTORS > 0
+  devnull_register();   /* Standard /dev/null */
+#endif
+
+  /* Initialize the serial device driver */
+
+  up_serialinit();
+
+  /* Initialize the netwok */
+
+  up_netinitialize();
+  up_ledon(LED_IRQSENABLED);
+}
diff --git a/nuttx/arch/z80/src/common/up_initialstate.c b/nuttx/arch/z80/src/common/up_initialstate.c
new file mode 100644
index 000000000..0c87aa51d
--- /dev/null
+++ b/nuttx/arch/z80/src/common/up_initialstate.c
@@ -0,0 +1,91 @@
+/****************************************************************************
+ * common/up_initialstate.c
+ *
+ *   Copyright (C) 2007, 2008 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <sys/types.h>
+#include <string.h>
+#include <nuttx/arch.h>
+
+#include "up_internal.h"
+#include "up_arch.h"
+
+/****************************************************************************
+ * Private Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Funtions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Funtions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: up_initial_state
+ *
+ * Description:
+ *   A new thread is being started and a new TCB
+ *   has been created. This function is called to initialize
+ *   the processor specific portions of the new TCB.
+ *
+ *   This function must setup the intial architecture registers
+ *   and/or  stack so that execution will begin at tcb->start
+ *   on the next context switch.
+ *
+ ****************************************************************************/
+
+void up_initial_state(_TCB *tcb)
+{
+  struct xcptcontext *xcp = &tcb->xcp;
+
+  /* Initialize the initial exception register context structure */
+
+  memset(xcp, 0, sizeof(struct xcptcontext));
+#ifndef CONFIG_SUPPRESS_INTERRUPTS
+  xcp->regs[XCPT_I]  = 0x0001; /* Carry flag will enable interrupts */
+#endif
+  xcp->regs[XCPT_SP] = (uint16)tcb->adj_stack_ptr;
+  xcp->regs[XCPT_PC] = (uint16)tcb->start;
+}
diff --git a/nuttx/arch/z80/src/common/up_internal.h b/nuttx/arch/z80/src/common/up_internal.h
new file mode 100644
index 000000000..e3da89213
--- /dev/null
+++ b/nuttx/arch/z80/src/common/up_internal.h
@@ -0,0 +1,184 @@
+/****************************************************************************
+ * common/up_internal.h
+ *
+ *   Copyright (C) 2007, 2008 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+#ifndef __UP_INTERNAL_H
+#define __UP_INTERNAL_H
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <arch/irq.h>
+#include <chip/chip.h>
+
+/****************************************************************************
+ * Definitions
+ ****************************************************************************/
+
+/* Bring-up debug configurations.  These are here (vs defconfig)
+ * because these should only be controlled during low level
+ * board bring-up and not part of normal platform configuration.
+ */
+
+#undef  CONFIG_SUPPRESS_INTERRUPTS    /* Do not enable interrupts */
+#undef  CONFIG_SUPPRESS_TIMER_INTS    /* No timer */
+#undef  CONFIG_SUPPRESS_SERIAL_INTS   /* Console will poll */
+#undef  CONFIG_SUPPRESS_UART_CONFIG   /* Do not reconfig UART */
+#define CONFIG_DUMP_ON_EXIT         1 /* Dump task state on exit */
+
+/* Macros for portability */
+
+#define IN_INTERRUPT             (current_regs != NULL)
+#define SAVE_IRQCONTEXT(tcb)     up_copystate((tcb)->xcp.regs, current_regs)
+#define SET_IRQCONTEXT(tcb)      up_copystate(current_regs, (tcb)->xcp.regs)
+#define SAVE_USERCONTEXT(tcb)    up_saveusercontext((tcb)->xcp.regs)
+#define RESTORE_USERCONTEXT(tcb) up_restoreusercontext((tcb)->xcp.regs)
+
+/****************************************************************************
+ * Public Types
+ ****************************************************************************/
+
+#ifndef __ASSEMBLY__
+typedef void (*up_vector_t)(void);
+#endif
+
+/****************************************************************************
+ * Public Variables
+ ****************************************************************************/
+
+#ifndef __ASSEMBLY__
+/* This holds a references to the current interrupt level
+ * register storage structure.  If is non-NULL only during
+ * interrupt processing.
+ */
+
+extern uint16 *current_regs;
+#endif
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+#ifndef __ASSEMBLY__
+
+/* Defined in up_copystate.c */
+
+extern void up_copystate(FAR chipreg_t *dest, FAR const chipreg_t *src);
+
+/* Defined in up_saveusercontext.asm */
+
+extern int up_saveusercontext(chipreg_t *regs);
+
+/* Defined in up_restoreusercontext.asm */
+
+extern int up_restoreusercontext(chipreg_t *regs);
+
+/* Supplied by board-specific logic */
+
+extern FAR chipreg_t *up_decodeirq(FAR chipreg_t *regs);
+extern void up_irqinitialize(void);
+extern int  up_timerisr(int irq, FAR chipreg_t *regs);
+
+/* Defined in up_doirq.c */
+
+extern void up_doirq(int irq, FAR chipreg_t *regs);
+
+/* Define in up_sigdeliver */
+
+extern void up_sigdeliver(void);
+
+#ifdef CONFIG_DEBUG
+extern void up_lowputc(char ch);
+#else
+# define up_lowputc(ch)
+#endif
+
+/* Defined in up_allocateheap.c */
+
+#if CONFIG_MM_REGIONS > 1
+void up_addregion(void);
+#endif
+
+/* Defined in up_serial.c */
+
+#if CONFIG_NFILE_DESCRIPTORS > 0
+extern void up_earlyserialinit(void);
+extern void up_serialinit(void);
+#else
+# define up_earlyserialinit()
+# define up_serialinit()
+#endif
+
+/* Defined in up_timerisr.c */
+
+extern void up_timerinit(void);
+
+/* Defined in board/up_leds.c */
+
+#ifdef CONFIG_ARCH_LEDS
+extern void up_ledinit(void);
+extern void up_ledon(int led);
+extern void up_ledoff(int led);
+#else
+# define up_ledinit()
+# define up_ledon(led)
+# define up_ledoff(led)
+#endif
+
+/* Defined in board/up_network.c */
+
+#ifdef CONFIG_NET
+extern void up_netinitialize(void);
+#else
+# define up_netinitialize()
+#endif
+
+/* Return the current value of the stack pointer (used in stack dump logic) */
+
+extern uint16 up_getsp(void);
+
+/* Dump stack and registers */
+
+#ifdef CONFIG_ARCH_STACKDUMP
+extern void up_stackdump(void);
+extern void up_registerdump(void);
+#else
+# define up_stackdump()
+# define up_registerdump()
+#endif
+
+#endif /* __ASSEMBLY__ */
+
+#endif  /* __UP_INTERNAL_H */
diff --git a/nuttx/arch/z80/src/common/up_interruptcontext.c b/nuttx/arch/z80/src/common/up_interruptcontext.c
new file mode 100644
index 000000000..6e9e752c9
--- /dev/null
+++ b/nuttx/arch/z80/src/common/up_interruptcontext.c
@@ -0,0 +1,68 @@
+/****************************************************************************
+ * common/up_interruptcontext.c
+ *
+ *   Copyright (C) 2007, 2008 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+#include <sys/types.h>
+#include <nuttx/arch.h>
+#include <nuttx/irq.h>
+#include "up_internal.h"
+
+/****************************************************************************
+ * Private Types
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Function Prototypes
+ ****************************************************************************/
+
+/****************************************************************************
+ * Global Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: up_interrupt_context
+ *
+ * Description: Return TRUE is we are currently executing in
+ * the interrupt handler context.
+ ****************************************************************************/
+
+boolean up_interrupt_context(void)
+{
+   return current_regs != NULL;
+}
diff --git a/nuttx/arch/z80/src/common/up_mdelay.c b/nuttx/arch/z80/src/common/up_mdelay.c
new file mode 100644
index 000000000..33a813063
--- /dev/null
+++ b/nuttx/arch/z80/src/common/up_mdelay.c
@@ -0,0 +1,94 @@
+/****************************************************************************
+ * common/up_mdelay.c
+ *
+ *   Copyright (C) 2007, 2008 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+#include <nuttx/arch.h>
+
+#ifdef CONFIG_BOARD_LOOPSPERMSEC
+
+/****************************************************************************
+ * Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Types
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Function Prototypes
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Variables
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: up_mdelay
+ *
+ * Description:
+ *   Delay inline for the requested number of milliseconds.
+ *   *** NOT multi-tasking friendly ***
+ *
+ * ASSUMPTIONS:
+ *   The setting CONFIG_BOARD_LOOPSPERMSEC has been calibrated
+ *
+ ****************************************************************************/
+
+void up_mdelay(unsigned int milliseconds)
+{
+  volatile int i;
+  volatile int j;
+
+  for (i = 0; i < milliseconds; i++)
+    {
+        for (j = 0; j < CONFIG_BOARD_LOOPSPERMSEC; j++)
+          {
+          }
+    }
+}
+#endif /* CONFIG_BOARD_LOOPSPERMSEC */
+
diff --git a/nuttx/arch/z80/src/common/up_registerdump.c b/nuttx/arch/z80/src/common/up_registerdump.c
new file mode 100644
index 000000000..05761bf85
--- /dev/null
+++ b/nuttx/arch/z80/src/common/up_registerdump.c
@@ -0,0 +1,91 @@
+/****************************************************************************
+ * common/up_registerdump.c
+ *
+ *   Copyright (C) 2007, 2008 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <sys/types.h>
+#include <debug.h>
+
+#include <nuttx/irq.h>
+#include <nuttx/arch.h>
+
+#include "os_internal.h"
+#include "up_internal.h"
+
+/****************************************************************************
+ * Definitions
+ ****************************************************************************/
+
+/* Output debug info if stack dump is selected -- even if 
+ * debug is not selected.
+ */
+
+#ifdef CONFIG_ARCH_STACKDUMP
+# undef  lldbg
+# define lldbg lib_lowprintf
+#endif
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: up_registerdump
+ ****************************************************************************/
+
+#ifdef CONFIG_ARCH_STACKDUMP
+static void up_registerdump(void)
+{
+  if (current_regs)
+    {
+      lldbg("AF: %04x  I: %04x\n",
+            current_regs[XCPT_AF], current_regs[XCPT_I]);
+      lldbg("BC: %04x DE: %04x HL: %04x\n",
+            current_regs[XCPT_BC], current_regs[XCPT_DE], current_regs[XCPT_HL]);
+      lldbg("IX: %04x IY: %04x\n",
+            current_regs[XCPT_IX], current_regs[XCPT_IY]);
+      lldbg("SP: %04x PC: $04x\n"
+            current_regs[XCPT_SP], current_regs[XCPT_PC]);
+    }
+}
+#endif
diff --git a/nuttx/arch/z80/src/common/up_releasepending.c b/nuttx/arch/z80/src/common/up_releasepending.c
new file mode 100644
index 000000000..8bf0bf798
--- /dev/null
+++ b/nuttx/arch/z80/src/common/up_releasepending.c
@@ -0,0 +1,137 @@
+/****************************************************************************
+ * common/up_releasepending.c
+ *
+ *   Copyright (C) 2007, 2008 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <sys/types.h>
+#include <sched.h>
+#include <debug.h>
+
+#include <nuttx/arch.h>
+#include <chip/chip.h>
+
+#include "os_internal.h"
+#include "up_internal.h"
+
+/****************************************************************************
+ * Private Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Funtions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Funtions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: up_release_pending
+ *
+ * Description:
+ *   Release and ready-to-run tasks that have
+ *   collected in the pending task list.  This can call a
+ *   context switch if a new task is placed at the head of
+ *   the ready to run list.
+ *
+ ****************************************************************************/
+
+void up_release_pending(void)
+{
+  FAR _TCB *rtcb = (FAR _TCB*)g_readytorun.head;
+
+  lldbg("From TCB=%p\n", rtcb);
+
+  /* Merge the g_pendingtasks list into the g_readytorun task list */
+
+  /* sched_lock(); */
+  if (sched_mergepending())
+    {
+      /* The currently active task has changed!  We will need to
+       * switch contexts.  First check if we are operating in
+       * interrupt context:
+       */
+
+      if (IN_INTERRUPT)
+        {
+          /* Yes, then we have to do things differently.
+           * Just copy the current context into the OLD rtcb.
+           */
+
+           SAVE_IRQCONTEXT(rtcb);
+
+          /* Restore the exception context of the rtcb at the (new) head 
+           * of the g_readytorun task list.
+           */
+
+          rtcb = (FAR _TCB*)g_readytorun.head;
+          lldbg("New Active Task TCB=%p\n", rtcb);
+
+          /* Then setup so that the context will be performed on exit
+           * from the interrupt.
+           */
+
+          SET_IRQCONTEXT(rtcb);
+        }
+
+      /* Copy the exception context into the TCB of the task that
+       * was currently active. if SAVE_USERCONTEXT returns a non-zero
+       * value, then this is really the previously running task 
+       * restarting!
+       */
+
+      else if (!SAVE_USERCONTEXT(rtcb))
+        {
+          /* Restore the exception context of the rtcb at the (new) head 
+           * of the g_readytorun task list.
+           */
+
+          rtcb = (FAR _TCB*)g_readytorun.head;
+          lldbg("New Active Task TCB=%p\n", rtcb);
+
+          /* Then switch contexts */
+
+          RESTORE_USERCONTEXT(rtcb);
+        }
+    }
+}
diff --git a/nuttx/arch/z80/src/common/up_releasestack.c b/nuttx/arch/z80/src/common/up_releasestack.c
new file mode 100644
index 000000000..b00b9ab0c
--- /dev/null
+++ b/nuttx/arch/z80/src/common/up_releasestack.c
@@ -0,0 +1,78 @@
+/************************************************************
+ * common/up_releasestack.c
+ *
+ *   Copyright (C) 2007 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name Gregory Nutt nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ************************************************************/
+
+/************************************************************
+ * Included Files
+ ************************************************************/
+
+#include <nuttx/config.h>
+#include <sys/types.h>
+#include <sched.h>
+#include <debug.h>
+#include <nuttx/arch.h>
+#include "os_internal.h"
+#include "up_internal.h"
+
+/************************************************************
+ * Private Types
+ ************************************************************/
+
+/************************************************************
+ * Private Function Prototypes
+ ************************************************************/
+
+/************************************************************
+ * Global Functions
+ ************************************************************/
+
+/************************************************************
+ * Name: up_release_stack
+ *
+ * Description:
+ *   A task has been stopped. Free all stack
+ *   related resources retained int the defunct TCB.
+ *
+ ************************************************************/
+
+void up_release_stack(_TCB *dtcb)
+{
+  if (dtcb->stack_alloc_ptr)
+    {
+      sched_free(dtcb->stack_alloc_ptr);
+      dtcb->stack_alloc_ptr = NULL;
+    }
+
+  dtcb->adj_stack_size = 0;
+}
diff --git a/nuttx/arch/z80/src/common/up_reprioritizertr.c b/nuttx/arch/z80/src/common/up_reprioritizertr.c
new file mode 100644
index 000000000..e90bd7186
--- /dev/null
+++ b/nuttx/arch/z80/src/common/up_reprioritizertr.c
@@ -0,0 +1,185 @@
+/****************************************************************************
+ * common/up_reprioritizertr.c
+ *
+ *   Copyright (C) 2007, 2008 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <sys/types.h>
+#include <sched.h>
+#include <debug.h>
+
+#include <nuttx/arch.h>
+#include <chip/chip.h>
+
+#include "os_internal.h"
+#include "up_internal.h"
+
+/****************************************************************************
+ * Private Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Funtions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Funtions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: up_reprioritize_rtr
+ *
+ * Description:
+ *   Called when the priority of a running or
+ *   ready-to-run task changes and the reprioritization will 
+ *   cause a context switch.  Two cases:
+ *
+ *   1) The priority of the currently running task drops and the next
+ *      task in the ready to run list has priority.
+ *   2) An idle, ready to run task's priority has been raised above the
+ *      the priority of the current, running task and it now has the
+ *      priority.
+ *
+ * Inputs:
+ *   tcb: The TCB of the task that has been reprioritized
+ *   priority: The new task priority
+ *
+ ****************************************************************************/
+
+void up_reprioritize_rtr(FAR _TCB *tcb, ubyte priority)
+{
+  /* Verify that the caller is sane */
+
+  if (tcb->task_state < FIRST_READY_TO_RUN_STATE ||
+      tcb->task_state > LAST_READY_TO_RUN_STATE ||
+      priority < SCHED_PRIORITY_MIN || 
+      priority > SCHED_PRIORITY_MAX)
+    {
+       PANIC(OSERR_BADREPRIORITIZESTATE);
+    }
+  else
+    {
+      FAR _TCB *rtcb = (FAR _TCB*)g_readytorun.head;
+      boolean switch_needed;
+
+      lldbg("TCB=%p PRI=%d\n", tcb, priority);
+
+      /* Remove the tcb task from the ready-to-run list.
+       * sched_removereadytorun will return TRUE if we just
+       * remove the head of the ready to run list.
+       */
+
+      switch_needed = sched_removereadytorun(tcb);
+
+      /* Setup up the new task priority */
+
+      tcb->sched_priority = (ubyte)priority;
+
+      /* Return the task to the specified blocked task list.
+       * sched_addreadytorun will return TRUE if the task was
+       * added to the new list.  We will need to perform a context
+       * switch only if the EXCLUSIVE or of the two calls is non-zero
+       * (i.e., one and only one the calls changes the head of the
+       * ready-to-run list).
+       */
+
+      switch_needed ^= sched_addreadytorun(tcb);
+
+      /* Now, perform the context switch if one is needed */
+
+      if (switch_needed)
+        {
+          /* If we are going to do a context switch, then now is the right
+           * time to add any pending tasks back into the ready-to-run list.
+           * task list now
+           */
+
+          if (g_pendingtasks.head)
+            {
+              sched_mergepending();
+            }
+
+          /* Are we in an interrupt handler? */
+
+          if (IN_INTERRUPT)
+            {
+              /* Yes, then we have to do things differently.
+               * Just copy the current context into the OLD rtcb.
+               */
+
+               SAVE_IRQCONTEXT(rtcb);
+
+              /* Restore the exception context of the rtcb at the (new) head 
+               * of the g_readytorun task list.
+               */
+
+              rtcb = (FAR _TCB*)g_readytorun.head;
+              lldbg("New Active Task TCB=%p\n", rtcb);
+
+              /* Then setup so that the context will be performed on exit
+               * from the interrupt.
+               */
+
+               SET_IRQCONTEXT(rtcb);
+            }
+
+          /* Copy the exception context into the TCB at the (old) head of the
+           * g_readytorun Task list. if SAVE_USERCONTEXT returns a non-zero
+           * value, then this is really the previously running task restarting!
+           */
+
+          else if (!SAVE_USERCONTEXT(rtcb))
+            {
+              /* Restore the exception context of the rtcb at the (new) head 
+               * of the g_readytorun task list.
+               */
+
+              rtcb = (FAR _TCB*)g_readytorun.head;
+              lldbg("New Active Task TCB=%p\n", rtcb);
+
+              /* Then switch contexts */
+
+              RESTORE_USERCONTEXT(rtcb);
+            }
+        }
+    }
+}
diff --git a/nuttx/arch/z80/src/common/up_restoreusercontext.asm b/nuttx/arch/z80/src/common/up_restoreusercontext.asm
new file mode 100644
index 000000000..093d18b7c
--- /dev/null
+++ b/nuttx/arch/z80/src/common/up_restoreusercontext.asm
@@ -0,0 +1,99 @@
+;**************************************************************************

+; arch/z80/src/common/up_restoreusercontext.asm

+;

+;   Copyright (C) 2007, 2008 Gregory Nutt. All rights reserved.

+;   Author: Gregory Nutt <spudmonkey@racsa.co.cr>

+;

+; Redistribution and use in source and binary forms, with or without

+; modification, are permitted provided that the following conditions

+; are met:

+;

+; 1. Redistributions of source code must retain the above copyright

+;    notice, this list of conditions and the following disclaimer.

+; 2. Redistributions in binary form must reproduce the above copyright

+;    notice, this list of conditions and the following disclaimer in

+;    the documentation and/or other materials provided with the

+;    distribution.

+; 3. Neither the name NuttX nor the names of its contributors may be

+;    used to endorse or promote products derived from this software

+;    without specific prior written permission.

+;

+; THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS

+; "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT

+; LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS

+; FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE

+; COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,

+; INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,

+; BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS

+; OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED

+; AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT

+; LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN

+; ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE

+; POSSIBILITY OF SUCH DAMAGE.

+;

+;**************************************************************************

+

+	; Register save area layout

+

+	XCPT_I	==  0		; Saved I w/interrupt state in carry

+	XCPT_AF	==  2		; Saved AF register

+	XCPT_BC	==  4		; Saved BC register

+	XCPT_DE	==  6		; Saved DE register

+	XCPT_HL	==  8		; Saved HL register

+	XCPT_IX	== 10		; Saved IX register

+	XCPT_IY	== 12		; Saved IY register

+	XCPT_SP	== 14		; Offset to SP at time of interrupt

+	XCPT_PC	== 16		; Offset to PC at time of interrupt

+

+;**************************************************************************

+; up_restoreusercontext

+;**************************************************************************

+

+	.org   0x0038			; Int mode 1

+        .area   TEXT    (ABS,OVR)

+up_restoreusercontext:

+	; On entry, stack contains return address (not used), then address

+	; of the register save structure

+

+	; Discard the return address, we won't be returning

+

+	pop	hl

+

+	; Get the address of the beginning of the state save area.  Each

+	; pop will increment to the next element of the structure

+

+	pop	hl		; BC = Address of save structure

+	ld	sp, hl		; SP points to top of storage area

+

+	; Disable interrupts while we muck with the alternative registers

+

+	; Restore registers.  HL points to the beginning of the reg structure to restore

+

+	ex	af, af'			; Select alternate AF

+	pop	af			; Offset 0: AF' = I with interrupt state in carry

+	pop	bc			; Offset 1: BC

+	pop	de			; Offset 2: DE

+	pop	ix			; Offset 3: IX

+	pop	iy			; Offset 4: IY

+	exx				;   Use alternate BC/DE/HL

+	pop	hl			; Offset 5: HL' = Stack pointer at time of interrupt

+	exx

+	pop	hl			; Offset 6: HL

+	pop	af			; Offset 7: AF

+

+	; Restore the stack pointer

+

+	exx

+	ld	sp, hl

+	exx

+

+	; Restore interrupt state

+

+	ex	af, af'			; Recover interrupt state

+	jnc	noinrestore		; No carry, IFF2=0, means disabled

+	ex	af, af'			; Restore AF (before enabling interrupts)

+	ei				; yes

+	ret

+noinrestore:

+	ex	af, af'			; Restore AF

+	ret

diff --git a/nuttx/arch/z80/src/common/up_saveusercontext.asm b/nuttx/arch/z80/src/common/up_saveusercontext.asm
new file mode 100644
index 000000000..9d25a7800
--- /dev/null
+++ b/nuttx/arch/z80/src/common/up_saveusercontext.asm
@@ -0,0 +1,143 @@
+;*************************************************************************
+; common/up_saveusercontext.S
+;
+;   Copyright (C) 2007 Gregory Nutt. All rights reserved.
+;   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+;
+; Redistribution and use in source and binary forms, with or without
+; modification, are permitted provided that the following conditions
+; are met:
+;
+; 1. Redistributions of source code must retain the above copyright
+;    notice, this list of conditions and the following disclaimer.
+; 2. Redistributions in binary form must reproduce the above copyright
+;    notice, this list of conditions and the following disclaimer in
+;    the documentation and/or other materials provided with the
+;    distribution.
+; 3. Neither the name Gregory Nutt nor the names of its contributors may be
+;    used to endorse or promote products derived from this software
+;    without specific prior written permission.
+;
+; THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+; "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+; LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+; FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+; COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+; INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+; BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+; OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+; AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+; LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+; ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+; POSSIBILITY OF SUCH DAMAGE.
+;
+;*************************************************************************
+
+;*************************************************************************
+; Constants
+;*************************************************************************
+
+	; Register save area layout
+
+	XCPT_I		==  0	; Saved I w/interrupt state in carry
+	XCPT_AF		==  2	; Saved AF register
+	XCPT_BC		==  4	; Saved BC register
+	XCPT_DE		==  6	; Saved DE register
+	XCPT_HL		==  8	; Saved HL register
+	XCPT_IX		== 10	; Saved IX register
+	XCPT_IY		== 12	; Saved IY register
+	XCPT_SP		== 14	; Offset to SP at time of interrupt
+	XCPT_PC		== 16	; Offset to PC at time of interrupt
+
+	; Stack frame
+
+	FRAME_IY	==  0	; Location of IY on the stack
+	FRAME_IX	==  2	; Location of IX on the stack
+	FRAME_RET	==  4	; Location of return address on the stack
+	FRAME_REGS	==  6	; Location of reg save area on stack
+
+	SP_OFFSET	== -6
+
+;*************************************************************************
+; Name: up_saveusercontext
+;*************************************************************************
+
+	.area	TEXT	(ABS,OVR)
+up_saveusercontext:
+	; Set up a stack frame
+
+	push	ix			; Save IX and IY
+	push	iy
+	ld	ix, #0
+	add	ix, sp			; IX = stack frame
+
+	; Fetch the address of the save area
+
+	ld	l, FRAME_REGS(ix)	; HL = save area address
+	ld	h, FRAME_REGS+1(ix)	;
+	ld	iy, #0
+	add	iy, hl			; IY = save area address
+
+	; Then save the registers
+
+	; Save the current interrupt state at offset 0
+
+	ld	a, i			; Get interrupt state
+	push	af
+	pop	hl
+	ld	(iy+XCPT_I), l		; Offset 0: I w/interrupt state in carry
+	ld	(iy+XCPT_I+1), h
+
+	; Save BC at offset 1
+
+	ld	(iy+XCPT_BC), c		; Offset 1: BC
+	ld	(iy+XCPT_BC+1), b
+
+	; DE is not preserved (offset 2)
+
+	; Save IX at offset 3
+
+	ld	l, FRAME_IX(ix)		; HL = Saved alue of IX
+	ld	h, FRAME_IX+1(ix)	;
+	ld	(iy+XCPT_IX), l		; Offset 3: IX
+	ld	(iy+XCPT_IX+1), h	;
+
+	; Save IY at offset 4
+
+	ld	l, FRAME_IY(ix)		; HL = Saved value of IY
+	ld	h, FRAME_IY+1(ix)	;
+	ld	(iy+XCPT_IY), l		; Offset 4: IY
+	ld	(iy+XCPT_IY+1), h
+
+	; Save that stack pointer as it would be upon return in offset 5
+
+	ld	hl, #SP_OFFSET		; Value of stack pointer on return
+	add	hl, sp
+	ld	(iy+XCPT_SP), l		; Offset 5 SP
+	ld	(iy+XCPT_SP+1), h
+
+	; HL is saved as the value 1 at offset 6
+
+	xor	a			; A = 0
+	ld	(iy+XCPT_HL+1), a	; Offset 2: HL on return (=1)
+	inc	a			; A = 1
+	ld	(iy+XCPT_HL), a		;
+
+	; AF is not preserved (offset 7)
+
+	; Save the return address in offset 8
+
+	ld	l, FRAME_RET(ix)	; HL = Saved return address
+	ld	h, FRAME_RET+1(ix)	;
+	ld	(iy+XCPT_PC), l		; Offset 8: PC
+	ld	(iy+XCPT_PC+1), h
+
+	; Return the value 0
+
+	xor	a			; HL = return value of zero
+	ld	l, a
+	ld	h, a
+
+	pop	iy
+	pop	ix
+	ret
diff --git a/nuttx/arch/z80/src/common/up_schedulesigaction.c b/nuttx/arch/z80/src/common/up_schedulesigaction.c
new file mode 100644
index 000000000..90039df17
--- /dev/null
+++ b/nuttx/arch/z80/src/common/up_schedulesigaction.c
@@ -0,0 +1,190 @@
+/************************************************************
+ * common/up_schedulesigaction.c
+ *
+ *   Copyright (C) 2007,2008 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ************************************************************/
+
+/************************************************************
+ * Included Files
+ ************************************************************/
+
+#include <nuttx/config.h>
+#include <sys/types.h>
+#include <sched.h>
+#include <debug.h>
+#include <nuttx/arch.h>
+#include "os_internal.h"
+#include "up_internal.h"
+#include "up_arch.h"
+
+/************************************************************
+ * Private Definitions
+ ************************************************************/
+
+/************************************************************
+ * Private Data
+ ************************************************************/
+
+/************************************************************
+ * Private Funtions
+ ************************************************************/
+
+/************************************************************
+ * Public Funtions
+ ************************************************************/
+
+/************************************************************
+ * Name: up_schedule_sigaction
+ *
+ * Description:
+ *   This function is called by the OS when one or more
+ *   signal handling actions have been queued for execution.
+ *   The architecture specific code must configure things so
+ *   that the 'igdeliver' callback is executed on the thread
+ *   specified by 'tcb' as soon as possible.
+ *
+ *   This function may be called from interrupt handling logic.
+ *
+ *   This operation should not cause the task to be unblocked
+ *   nor should it cause any immediate execution of sigdeliver.
+ *   Typically, a few cases need to be considered:
+ *
+ *   (1) This function may be called from an interrupt handler
+ *       During interrupt processing, all xcptcontext structures
+ *       should be valid for all tasks.  That structure should
+ *       be modified to invoke sigdeliver() either on return
+ *       from (this) interrupt or on some subsequent context
+ *       switch to the recipient task.
+ *   (2) If not in an interrupt handler and the tcb is NOT
+ *       the currently executing task, then again just modify
+ *       the saved xcptcontext structure for the recipient
+ *       task so it will invoke sigdeliver when that task is
+ *       later resumed.
+ *   (3) If not in an interrupt handler and the tcb IS the
+ *       currently executing task -- just call the signal
+ *       handler now.
+ *
+ ************************************************************/
+
+void up_schedule_sigaction(_TCB *tcb, sig_deliver_t sigdeliver)
+{
+  /* Refuse to handle nested signal actions */
+
+  dbg("tcb=0x%p sigdeliver=0x%p\n", tcb, sigdeliver);
+
+  if (!tcb->xcp.sigdeliver)
+    {
+      irqstate_t flags;
+
+      /* Make sure that interrupts are disabled */
+
+      flags = irqsave();
+
+      /* First, handle some special cases when the signal is
+       * being delivered to the currently executing task.
+       */
+
+      dbg("rtcb=0x%p current_regs=0x%p\n", g_readytorun.head, current_regs);
+
+      if (tcb == (_TCB*)g_readytorun.head)
+        {
+          /* CASE 1:  We are not in an interrupt handler and
+           * a task is signalling itself for some reason.
+           */
+
+          if (!current_regs)
+            {
+              /* In this case just deliver the signal now. */
+
+              sigdeliver(tcb);
+            }
+
+          /* CASE 2:  We are in an interrupt handler AND the
+           * interrupted task is the same as the one that
+           * must receive the signal, then we will have to modify
+           * the return state as well as the state in the TCB.
+           */
+
+          else
+            {
+              /* Save the return lr and cpsr and one scratch register
+               * These will be restored by the signal trampoline after
+               * the signals have been delivered.
+               */
+
+              tcb->xcp.sigdeliver    = sigdeliver;
+              tcb->xcp.saved_pc      = current_regs[REG_PC];
+              tcb->xcp.saved_cpsr    = current_regs[REG_CPSR];
+
+              /* Then set up to vector to the trampoline with interrupts
+               * disabled
+               */
+
+              current_regs[REG_PC]    = (uint32)up_sigdeliver;
+              current_regs[REG_CPSR]  = SVC_MODE | PSR_I_BIT | PSR_F_BIT;
+
+              /* And make sure that the saved context in the TCB
+               * is the same as the interrupt return context.
+               */
+
+              up_copystate(tcb->xcp.regs, current_regs);
+            }
+        }
+
+      /* Otherwise, we are (1) signaling a task is not running
+       * from an interrupt handler or (2) we are not in an
+       * interrupt handler and the running task is signalling
+       * some non-running task.
+       */
+
+      else
+        {
+          /* Save the return lr and cpsr and one scratch register
+           * These will be restored by the signal trampoline after
+           * the signals have been delivered.
+           */
+
+          tcb->xcp.sigdeliver    = sigdeliver;
+          tcb->xcp.saved_pc      = tcb->xcp.regs[REG_PC];
+          tcb->xcp.saved_cpsr    = tcb->xcp.regs[REG_CPSR];
+
+          /* Then set up to vector to the trampoline with interrupts
+           * disabled
+           */
+
+          tcb->xcp.regs[REG_PC]   = (uint32)up_sigdeliver;
+          tcb->xcp.regs[REG_CPSR] = SVC_MODE | PSR_I_BIT | PSR_F_BIT;
+        }
+
+      irqrestore(flags);
+    }
+}
diff --git a/nuttx/arch/z80/src/common/up_sigdeliver.c b/nuttx/arch/z80/src/common/up_sigdeliver.c
new file mode 100644
index 000000000..f8f0c79de
--- /dev/null
+++ b/nuttx/arch/z80/src/common/up_sigdeliver.c
@@ -0,0 +1,137 @@
+/************************************************************
+ * common/up_sigdeliver.c
+ *
+ *   Copyright (C) 2007 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name Gregory Nutt nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ************************************************************/
+
+/************************************************************
+ * Included Files
+ ************************************************************/
+
+#include <nuttx/config.h>
+#include <sys/types.h>
+#include <sched.h>
+#include <debug.h>
+#include <nuttx/irq.h>
+#include <nuttx/arch.h>
+#include "os_internal.h"
+#include "up_internal.h"
+#include "up_arch.h"
+
+/************************************************************
+ * Definitions
+ ************************************************************/
+
+/************************************************************
+ * Private Data
+ ************************************************************/
+
+/************************************************************
+ * Private Functions
+ ************************************************************/
+
+/************************************************************
+ * Public Funtions
+ ************************************************************/
+
+/************************************************************
+ * Name: up_sigdeliver
+ *
+ * Description:
+ *   This is the a signal handling trampoline.  When a
+ *   signal action was posted.  The task context was mucked
+ *   with and forced to branch to this location with interrupts
+ *   disabled.
+ *
+ ************************************************************/
+
+void up_sigdeliver(void)
+{
+#ifndef CONFIG_DISABLE_SIGNALS
+  _TCB  *rtcb = (_TCB*)g_readytorun.head;
+  uint32 regs[XCPTCONTEXT_REGS];
+  sig_deliver_t sigdeliver;
+
+  /* Save the errno.  This must be preserved throughout the
+   * signal handling so that the the user code final gets
+   * the correct errno value (probably EINTR).
+   */
+
+  int saved_errno = rtcb->errno;
+
+  up_ledon(LED_SIGNAL);
+
+  dbg("rtcb=%p sigdeliver=%p sigpendactionq.head=%p\n",
+       rtcb, rtcb->xcp.sigdeliver, rtcb->sigpendactionq.head);
+  ASSERT(rtcb->xcp.sigdeliver != NULL);
+
+  /* Save the real return state on the stack. */
+
+  up_copystate(regs, rtcb->xcp.regs);
+  regs[REG_PC]   = rtcb->xcp.saved_pc;
+  regs[REG_CPSR] = rtcb->xcp.saved_cpsr;
+
+  /* Get a local copy of the sigdeliver function pointer.
+   * we do this so that we can nullify the sigdeliver
+   * function point in the TCB and accept more signal
+   * deliveries while processing the current pending
+   * signals.
+   */
+
+  sigdeliver           = rtcb->xcp.sigdeliver;
+  rtcb->xcp.sigdeliver = NULL;
+
+  /* Then restore the task interrupt state. */
+
+  irqrestore(regs[REG_CPSR]);
+
+  /* Deliver the signals */
+
+  sigdeliver(rtcb);
+
+  /* Output any debug messaged BEFORE restoring errno
+   * (because they may alter errno), then restore the
+   * original errno that is needed by the user logic
+   * (it is probably EINTR).
+   */
+
+  dbg("Resuming\n");
+  rtcb->errno = saved_errno;
+
+  /* Then restore the correct state for this thread of
+   * execution.
+   */
+
+  up_ledoff(LED_SIGNAL);
+  up_fullcontextrestore(regs);
+#endif
+}
diff --git a/nuttx/arch/z80/src/common/up_stackdump.c b/nuttx/arch/z80/src/common/up_stackdump.c
new file mode 100644
index 000000000..00c923aa9
--- /dev/null
+++ b/nuttx/arch/z80/src/common/up_stackdump.c
@@ -0,0 +1,109 @@
+/****************************************************************************
+ * common/up_stackdump.c
+ *
+ *   Copyright (C) 2007, 2008 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <sys/types.h>
+#include <debug.h>
+
+#include "up_arch.h"
+#include "os_internal.h"
+#include "up_internal.h"
+
+/****************************************************************************
+ * Definitions
+ ****************************************************************************/
+
+/* Output debug info if stack dump is selected -- even if 
+ * debug is not selected.
+ */
+
+#ifdef CONFIG_ARCH_STACKDUMP
+# undef  lldbg
+# define lldbg lib_lowprintf
+#endif
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: up_getsp
+ ****************************************************************************/
+#warning TO BE PROVIDED
+
+/****************************************************************************
+ * Name: up_stackdump
+ ****************************************************************************/
+
+#ifdef CONFIG_ARCH_STACKDUMP
+static void up_stackdump(void)
+{
+  _TCB *rtcb        = (_TCB*)g_readytorun.head;
+  uint16 sp         = up_getsp();
+  uint16 stack_base = (uint16)rtcb->adj_stack_ptr;
+  uint16 stack_size = (uint16)rtcb->adj_stack_size;
+
+  lldbg("stack_base: %04x\n", stack_base);
+  lldbg("stack_size: %04x\n", stack_size);
+  lldbg("sp:         %04x\n", sp);
+
+  if (sp >= stack_base || sp < stack_base - stack_size)
+    {
+      lldbg("ERROR: Stack pointer is not within allocated stack\n");
+      return;
+    }
+  else
+    {
+      uint16 stack = sp & ~0x0f;
+
+      for (stack = sp & ~0x0f; stack < stack_base; stack += 8*sizeof(uint16))
+        {
+          uint16 *ptr = (uint16*)stack;
+          lldbg("%04x: %04x %04x %04x %04x %04x %04x %04x %04x\n",
+                 stack, ptr[0], ptr[1], ptr[2], ptr[3],
+                 ptr[4], ptr[5], ptr[6], ptr[7]);
+        }
+    }
+}
+#endif
diff --git a/nuttx/arch/z80/src/common/up_udelay.c b/nuttx/arch/z80/src/common/up_udelay.c
new file mode 100644
index 000000000..9982644ea
--- /dev/null
+++ b/nuttx/arch/z80/src/common/up_udelay.c
@@ -0,0 +1,132 @@
+/****************************************************************************
+ * common/up_udelay.c
+ *
+ *   Copyright (C) 2007 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name Gregory Nutt nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+#include <nuttx/arch.h>
+
+#ifdef CONFIG_BOARD_LOOPSPERMSEC
+
+/****************************************************************************
+ * Definitions
+ ****************************************************************************/
+
+#define CONFIG_BOARD_LOOPSPER100USEC ((CONFIG_BOARD_LOOPSPERMSEC+5)/10)
+#define CONFIG_BOARD_LOOPSPER10USEC  ((CONFIG_BOARD_LOOPSPERMSEC+50)/100)
+#define CONFIG_BOARD_LOOPSPERUSEC    ((CONFIG_BOARD_LOOPSPERMSEC+500)/1000)
+
+/****************************************************************************
+ * Private Types
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Function Prototypes
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Variables
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: up_udelay
+ *
+ * Description:
+ *   Delay inline for the requested number of microseconds.  NOTE:  Because
+ *   of all of the setup, several microseconds will be lost before the actual
+ *   timing looop begins.  Thus, the delay will always be a few microseconds
+ *   longer than requested.
+ *
+ *   *** NOT multi-tasking friendly ***
+ *
+ * ASSUMPTIONS:
+ *   The setting CONFIG_BOARD_LOOPSPERMSEC has been calibrated
+ *
+ ****************************************************************************/
+
+void up_udelay(unsigned int microseconds)
+{
+  volatile int i;
+
+  /* We'll do this a little at a time because we expect that the
+   * CONFIG_BOARD_LOOPSPERUSEC is very inaccurate during to truncation in
+   * the divisions of its calculation.  We'll use the largest values that
+   * we can in order to prevent significant error buildup in the loops.
+   */
+
+  while (microseconds > 1000)
+    {
+      for (i = 0; i < CONFIG_BOARD_LOOPSPERMSEC; i++)
+        {
+        }
+      microseconds -= 1000;
+    }
+
+  while (microseconds > 100)
+    {
+      for (i = 0; i < CONFIG_BOARD_LOOPSPER100USEC; i++)
+        {
+        }
+      microseconds -= 100;
+    }
+
+  while (microseconds > 10)
+    {
+      for (i = 0; i < CONFIG_BOARD_LOOPSPER10USEC; i++)
+        {
+        }
+      microseconds -= 10;
+    }
+
+  while (microseconds > 0)
+    {
+      for (i = 0; i < CONFIG_BOARD_LOOPSPERUSEC; i++)
+        {
+        }
+      microseconds--;
+    }
+}
+#endif /* CONFIG_BOARD_LOOPSPERMSEC */
+
diff --git a/nuttx/arch/z80/src/common/up_unblocktask.c b/nuttx/arch/z80/src/common/up_unblocktask.c
new file mode 100644
index 000000000..8934c700c
--- /dev/null
+++ b/nuttx/arch/z80/src/common/up_unblocktask.c
@@ -0,0 +1,168 @@
+/****************************************************************************
+ * common/up_unblocktask.c
+ *
+ *   Copyright (C) 2007, 2008 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <sys/types.h>
+#include <sched.h>
+#include <debug.h>
+
+#include <nuttx/arch.h>
+#include <chip/chip.h>
+
+#include "os_internal.h"
+#include "clock_internal.h"
+#include "up_internal.h"
+
+/****************************************************************************
+ * Private Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Funtions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Funtions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: up_unblock_task
+ *
+ * Description:
+ *   A task is currently in an inactive task list
+ *   but has been prepped to execute.  Move the TCB to the
+ *   ready-to-run list, restore its context, and start execution.
+ *
+ * Inputs:
+ *   tcb: Refers to the tcb to be unblocked.  This tcb is
+ *     in one of the waiting tasks lists.  It must be moved to
+ *     the ready-to-run list and, if it is the highest priority
+ *     ready to run taks, executed.
+ *
+ ****************************************************************************/
+
+void up_unblock_task(FAR _TCB *tcb)
+{
+  /* Verify that the context switch can be performed */
+
+  if ((tcb->task_state < FIRST_BLOCKED_STATE) ||
+      (tcb->task_state > LAST_BLOCKED_STATE))
+    {
+      PANIC(OSERR_BADUNBLOCKSTATE);
+    }
+  else
+    {
+      FAR _TCB *rtcb = (FAR _TCB*)g_readytorun.head;
+
+      /* dbg("Unblocking TCB=%p\n", tcb); */
+
+      /* Remove the task from the blocked task list */
+
+      sched_removeblocked(tcb);
+
+      /* Reset its timeslice.  This is only meaningful for round
+       * robin tasks but it doesn't here to do it for everything
+       */
+
+#if CONFIG_RR_INTERVAL > 0
+      tcb->timeslice = CONFIG_RR_INTERVAL / MSEC_PER_TICK;
+#endif
+
+      /* Add the task in the correct location in the prioritized
+       * g_readytorun task list
+       */
+
+      if (sched_addreadytorun(tcb))
+        {
+          /* The currently active task has changed! We need to do
+           * a context switch to the new task.
+           *
+           * Are we in an interrupt handler? 
+           */
+
+          if (IN_INTERRUPT)
+            {
+              /* Yes, then we have to do things differently.
+               * Just copy the current context into the OLD rtcb.
+               */
+
+               SAVE_IRQCONTEXT(rtcb);
+
+              /* Restore the exception context of the rtcb at the (new) head 
+               * of the g_readytorun task list.
+               */
+
+              rtcb = (FAR _TCB*)g_readytorun.head;
+              /* dbg("New Active Task TCB=%p\n", rtcb); */
+
+              /* Then setup so that the context will be performed on exit
+               * from the interrupt.
+               */
+
+              SET_IRQCONTEXT(rtcb);
+            }
+
+          /* We are not in an interrupt handler.  Copy the user C context
+           * into the TCB of the task that was previously active.  if 
+           * SAVE_USERCONTEXT returns a non-zero value, then this is really the
+           * previously running task restarting!
+           */
+
+          else if (!SAVE_USERCONTEXT(rtcb))
+            {
+              /* Restore the exception context of the new task that is ready to
+               * run (probably tcb).  This is the new rtcb at the head of the
+               * g_readytorun task list.
+               */
+
+              rtcb = (FAR _TCB*)g_readytorun.head;
+              /* dbg("New Active Task TCB=%p\n", rtcb); */
+
+              /* Then switch contexts */
+
+              RESTORE_USERCONTEXT(rtcb);
+            }
+        }
+    }
+}
diff --git a/nuttx/arch/z80/src/common/up_usestack.c b/nuttx/arch/z80/src/common/up_usestack.c
new file mode 100644
index 000000000..2da044182
--- /dev/null
+++ b/nuttx/arch/z80/src/common/up_usestack.c
@@ -0,0 +1,118 @@
+/************************************************************
+ * common/up_usestack.c
+ *
+ *   Copyright (C) 2007 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name Gregory Nutt nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ************************************************************/
+
+/************************************************************
+ * Included Files
+ ************************************************************/
+
+#include <nuttx/config.h>
+#include <sys/types.h>
+#include <sched.h>
+#include <debug.h>
+#include <nuttx/kmalloc.h>
+#include <nuttx/arch.h>
+#include "up_internal.h"
+
+/************************************************************
+ * Private Types
+ ************************************************************/
+
+/************************************************************
+ * Private Function Prototypes
+ ************************************************************/
+
+/************************************************************
+ * Global Functions
+ ************************************************************/
+
+/************************************************************
+ * Name: up_use_stack
+ *
+ * Description:
+ *   Setup up stack-related information in the TCB
+ *   using pre-allocated stack memory
+ *
+ *   The following TCB fields must be initialized:
+ *   adj_stack_size: Stack size after adjustment for hardware,
+ *     processor, etc.  This value is retained only for debug
+ *     purposes.
+ *   stack_alloc_ptr: Pointer to allocated stack
+ *   adj_stack_ptr: Adjusted stack_alloc_ptr for HW.  The
+ *     initial value of the stack pointer.
+ *
+ * Inputs:
+ *   tcb: The TCB of new task
+ *   stack_size:  The allocated stack size.
+ *
+ ************************************************************/
+
+STATUS up_use_stack(_TCB *tcb, void *stack, size_t stack_size)
+{
+  size_t top_of_stack;
+  size_t size_of_stack;
+
+  if (tcb->stack_alloc_ptr)
+    {
+      sched_free(tcb->stack_alloc_ptr);
+    }
+
+  /* Save the stack allocation */
+
+  tcb->stack_alloc_ptr = stack;
+
+  /* The Arm7Tdmi uses a push-down stack:  the stack grows
+   * toward loweraddresses in memory.  The stack pointer
+   * register, points to the lowest, valid work address
+   * (the "top" of the stack).  Items on the stack are
+   * referenced as positive word offsets from sp.
+   */
+
+  top_of_stack = (uint32)tcb->stack_alloc_ptr + stack_size - 4;
+
+  /* The Arm7Tdmi stack must be aligned at word (4 byte)
+   * boundaries. If necessary top_of_stack must be rounded
+   * down to the next boundary
+   */
+
+  top_of_stack &= ~3;
+  size_of_stack = top_of_stack - (uint32)tcb->stack_alloc_ptr + 4;
+
+  /* Save the adjusted stack values in the _TCB */
+
+  tcb->adj_stack_size = top_of_stack;
+  tcb->adj_stack_size = size_of_stack;
+
+  return OK;
+}
diff --git a/nuttx/arch/z80/src/z80/Make.defs b/nuttx/arch/z80/src/z80/Make.defs
new file mode 100644
index 000000000..80d5c7c0b
--- /dev/null
+++ b/nuttx/arch/z80/src/z80/Make.defs
@@ -0,0 +1,48 @@
+############################################################################
+# sdcc/src/z80/Make.defs
+#
+#   Copyright (C) 2007 Gregory Nutt. All rights reserved.
+#   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions
+# are met:
+#
+# 1. Redistributions of source code must retain the above copyright
+#    notice, this list of conditions and the following disclaimer.
+# 2. Redistributions in binary form must reproduce the above copyright
+#    notice, this list of conditions and the following disclaimer in
+#    the documentation and/or other materials provided with the
+#    distribution.
+# 3. Neither the name Gregory Nutt nor the names of its contributors may be
+#    used to endorse or promote products derived from this software
+#    without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+# FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+# COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+# INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+# BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+# OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+# AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+# ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+# POSSIBILITY OF SUCH DAMAGE.
+#
+############################################################################
+
+HEAD_ASRC	= up_head.asm
+
+CMN_ASRCS	= up_saveusercontext.asm up_restoreusercontext.asm
+CMN_CSRCS	= up_initialize.c up_allocateheap.c up_initialstate.c \
+		  up_createstack.c up_releasestack.c up_interruptcontext.c \
+		  up_blocktask.c  up_unblocktask.c up_exit.c up_releasepending.c \
+		  up_reprioritizertr.c up_copystate.c up_idle.c \
+		  up_assert.c up_mdelay.c up_udelay.c \
+		  up_registerdump.c up_usestack.c \
+
+CHIP_ASRCS	= 
+CHIP_CSRCS	= 
+
diff --git a/nuttx/arch/z80/src/z80/chip.h b/nuttx/arch/z80/src/z80/chip.h
new file mode 100644
index 000000000..9f85f1475
--- /dev/null
+++ b/nuttx/arch/z80/src/z80/chip.h
@@ -0,0 +1,66 @@
+/************************************************************************************
+ * z80/chip.h
+ * chip/chip.h
+ *
+ *   Copyright (C) 2007, 2008 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ************************************************************************************/
+
+#ifndef __Z80_CHIP_H
+#define __Z80_CHIP_H
+
+/************************************************************************************
+ * Included Files
+ ************************************************************************************/
+
+/************************************************************************************
+ * Definitions
+ ************************************************************************************/
+
+/************************************************************************************
+ * Public Function Prototypes
+ ************************************************************************************/
+
+#ifndef __ASSEMBLY__
+#ifdef __cplusplus
+#define EXTERN extern "C"
+extern "C" {
+#else
+#define EXTERN extern
+#endif
+
+#undef EXTERN
+#ifdef __cplusplus
+}
+#endif
+#endif
+
+#endif  /* __Z80_CHIP_H */
diff --git a/nuttx/configs/z80sim/Make.defs b/nuttx/configs/z80sim/Make.defs
new file mode 100644
index 000000000..73ba579b7
--- /dev/null
+++ b/nuttx/configs/z80sim/Make.defs
@@ -0,0 +1,83 @@
+############################################################################
+# Make.defs
+#
+#   Copyright (C) 2007, 2008 Gregory Nutt. All rights reserved.
+#   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions
+# are met:
+#
+# 1. Redistributions of source code must retain the above copyright
+#    notice, this list of conditions and the following disclaimer.
+# 2. Redistributions in binary form must reproduce the above copyright
+#    notice, this list of conditions and the following disclaimer in
+#    the documentation and/or other materials provided with the
+#    distribution.
+# 3. Neither the name Gregory Nutt nor the names of its contributors may be
+#    used to endorse or promote products derived from this software
+#    without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+# FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+# COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+# INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+# BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+# OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+# AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+# ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+# POSSIBILITY OF SUCH DAMAGE.
+#
+############################################################################
+
+include ${TOPDIR}/.config
+
+ifeq ("${CONFIG_DEBUG}","y")
+  ARCHOPTIMIZATION	= --debug
+else
+  ARCHOPTIMIZATION	=
+endif
+
+ARCHCPUFLAGS		= -mz80 --stack-auto --int-long-reent --float-reent
+ARCHPICFLAGS		=
+ARCHWARNINGS		=
+ARCHDEFINES		=
+ARCHINCLUDES		= -I. -I$(TOPDIR)/include
+
+CROSSDEV		=
+CC			= sdcc
+CPP			= sdcpp
+LD			= link-z80
+AS			= as-z80
+AR			= sdcclib -a
+
+CFLAGS			= $(ARCHWARNINGS) $(ARCHOPTIMIZATION) \
+			  $(ARCHCPUFLAGS) $(ARCHINCLUDES) $(ARCHDEFINES)
+CPPFLAGS		= $(ARCHINCLUDES) $(ARCHDEFINES)
+ASFLAGS			= 
+
+SDCCLIBDIR		= /usr/local/share/sdcc/lib/z80
+SDCCPATH		= -L$(SDCCLIBDIR)
+SDCCLIBS		= -lz80.lib
+
+IRAM_SIZE		= 0x100
+DEF_STACK_BASE		= 0x24
+LDFLAGS			= --model-large --nostdlib \
+			  --data-loc $(DEF_STACK_BASE) --iram-size $(IRAM_SIZE) \
+			  --code-loc 0x2100 --code-size 0x5f40 \
+			  --xram-loc $(IRAM_SIZE) --xram-size 0x1f00
+
+ASMEXT			= .asm
+OBJEXT			= .o
+LIBEXT			= .lib
+EXEEXT			= .hex
+
+HOSTCC			= gcc
+HOSTINCLUDES		= -I.
+HOSTCFLAGS		= -Wall -wstrict-prototypes -Wshadow -g -pipe
+HOSTLDFLAGS		=
+
+
diff --git a/nuttx/configs/z80sim/README.txt b/nuttx/configs/z80sim/README.txt
new file mode 100644
index 000000000..50be916e1
--- /dev/null
+++ b/nuttx/configs/z80sim/README.txt
@@ -0,0 +1,20 @@
+pjrc-8051 README
+^^^^^^^^^^^^^^^^
+
+This port uses a primitive, simulated Z80 and the SDCC toolchain.
+
+The SDCC toolchain is available from http://sdcc.sourceforge.net/.  All
+testing has been performed using verison 2.6.0 of the SDDC toolchain.
+
+Building the SDCC toolchain
+^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+The SDCC toolchain is built with the standard configure/make/make install
+sequence.  However, some special actions are required to generate libraries
+compatible with this build.  First start with the usual steps
+
+  download
+  unpack
+  cd sdcc
+  ./configure
+  make
diff --git a/nuttx/configs/z80sim/defconfig b/nuttx/configs/z80sim/defconfig
new file mode 100644
index 000000000..a806bfc6b
--- /dev/null
+++ b/nuttx/configs/z80sim/defconfig
@@ -0,0 +1,289 @@
+############################################################
+# defconfig
+#
+#   Copyright (C) 2007 Gregory Nutt. All rights reserved.
+#   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions
+# are met:
+#
+# 1. Redistributions of source code must retain the above copyright
+#    notice, this list of conditions and the following disclaimer.
+# 2. Redistributions in binary form must reproduce the above copyright
+#    notice, this list of conditions and the following disclaimer in
+#    the documentation and/or other materials provided with the
+#    distribution.
+# 3. Neither the name Gregory Nutt nor the names of its contributors may be
+#    used to endorse or promote products derived from this software
+#    without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+# FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+# COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+# INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+# BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+# OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+# AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+# ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+# POSSIBILITY OF SUCH DAMAGE.
+#
+############################################################
+#
+# Architecture selection
+#
+# CONFIG_ARCH - identifies the arch subdirectory and, hence, the
+#   processor architecture.
+# CONFIG_ARCH_8051 - Set if processor is 8051 family
+# CONFIG_ARCH_8052 = Set if processor is 8052 family
+# CONFIG_ARCH_BOARD - identifies the configs subdirectory and, hence,
+#   the board that supports the particular chip or SoC.
+# CONFIG_ARCH_BOARD_name - for use in C code
+# CONFIG_DRAM_SIZE - Describes the installed DRAM.
+#
+CONFIG_ARCH=z80
+CONFIG_ARCH_Z80=y
+CONFIG_ARCH_CHIP=z80
+CONFIG_ARCH_CHIP_Z80=1
+CONFIG_ARCH_BOARD=z80sim
+CONFIG_DRAM_SIZE=65536
+
+#
+# General OS setup
+#
+# CONFIG_EXAMPLE - identifies the subdirectory in examples
+#   that will be used in the build
+# CONFIG_DEBUG - enables built-in debug options
+# CONFIG_DEBUG_VERBOSE - enables verbose debug output
+# CONFIG_MM_REGIONS - If the architecture includes multiple
+#   regions of memory to allocate from, this specifies the
+#   number of memory regions that the memory manager must
+#   handle and enables the API mm_addregion(start, end);
+# CONFIG_HAVE_LOWPUTC - architecture supports low-level, boot
+#   time console output
+# CONFIG_TICKS_PER_MSEC - The default system timer is 100Hz
+#   or TICKS_PER_MSEC=10.  This setting may be defined to
+#   inform NuttX that the processor hardware is providing
+#   system timer interrupts at some interrupt interval other
+#   than 10 msec.
+# CONFIG_RR_INTERVAL - The round robin timeslice will be set
+#   this number of milliseconds;  Round robin scheduling can
+#   be disabled by setting this value to zero.
+# CONFIG_SCHED_INSTRUMENTATION - enables instrumentation in 
+#   scheduler to monitor system performance
+# CONFIG_TASK_NAME_SIZE - Spcifies that maximum size of a
+#   task name to save in the TCB.  Useful if scheduler
+#   instrumentation is selected.  Set to zero to disable.
+# CONFIG_JULIAN_TIME - Enables Julian time conversions
+# CONFIG_START_YEAR, CONFIG_START_MONTH, CONFIG_START_DAY -
+#   Used to initialize the internal time logic.
+# CONFIG_DEV_CONSOLE - Set if architecture-specific logic
+#   provides /dev/console.  Enables stdout, stderr, stdin.
+#
+CONFIG_EXAMPLE=ostest
+CONFIG_DEBUG=n
+CONFIG_DEBUG_VERBOSE=n
+CONFIG_MM_REGIONS=2
+CONFIG_ARCH_LOWPUTC=y
+CONFIG_RR_INTERVAL=0
+CONFIG_SCHED_INSTRUMENTATION=n
+CONFIG_TASK_NAME_SIZE=0
+CONFIG_START_YEAR=2007
+CONFIG_START_MONTH=2
+CONFIG_START_DAY=21
+CONFIG_JULIAN_TIME=n
+CONFIG_DEV_CONSOLE=n
+
+#
+# The following can be used to disable categories of
+# APIs supported by the OS.  If the compiler supports
+# weak functions, then it should not be necessary to
+# disable functions unless you want to restrict usage
+# of those APIs.
+#
+# There are certain dependency relationships in these
+# features.
+#
+# o mq_notify logic depends on signals to awaken tasks
+#   waiting for queues to become full or empty.
+# o pthread_condtimedwait() depends on signals to wake
+#   up waiting tasks.
+#
+CONFIG_DISABLE_CLOCK=y
+CONFIG_DISABLE_POSIX_TIMERS=y
+CONFIG_DISABLE_PTHREAD=y
+CONFIG_DISABLE_SIGNALS=y
+CONFIG_DISABLE_MQUEUE=y
+CONFIG_DISABLE_MOUNTPOINT=y
+CONFIG_DISABLE_ENVIRON=y
+
+#
+# Misc libc settings
+#
+# CONFIG_NOPRINTF_FIELDWIDTH - sprintf-related logic is a
+#   little smaller if we do not support fieldwidthes
+#
+CONFIG_NOPRINTF_FIELDWIDTH=y
+
+#
+# Allow for architecture optimized implementations
+#
+# The architecture can provide optimized versions of the
+# following to improve sysem performance
+#
+CONFIG_ARCH_MEMCPY=n
+CONFIG_ARCH_MEMCMP=n
+CONFIG_ARCH_MEMMOVE=n
+CONFIG_ARCH_MEMSET=n
+CONFIG_ARCH_STRCMP=n
+CONFIG_ARCH_STRCPY=n
+CONFIG_ARCH_STRNCPY=n
+CONFIG_ARCH_STRLEN=n
+CONFIG_ARCH_BZERO=n
+CONFIG_ARCH_KMALLOC=n
+CONFIG_ARCH_KZMALLOC=n
+CONFIG_ARCH_KFREE=n
+
+#
+# General build options
+#
+# CONFIG_RRLOAD_BINARY - make the rrload binary format used with
+#   BSPs from www.ridgerun.com
+#
+CONFIG_RRLOAD_BINARY=n
+
+#
+# Sizes of configurable things (0 disables)
+#
+# CONFIG_MAX_TASKS - The maximum number of simultaneously
+#   actived tasks.  This value must be a power of two.
+# CONFIG_MAX_TASK_ARGS - This controls the maximum number of
+#   of parameters that a task may receive (i.e., maxmum value
+#   of 'argc')
+# CONFIG_NPTHREAD_KEYS - The number of items of thread-
+#   specific data that can be retained
+# CONFIG_NFILE_DESCRIPTORS - The maximum number of file
+#   descriptors (one for each open)
+# CONFIG_NFILE_STREAMS - The maximum number of streams that
+#   can be fopen'ed
+# CONFIG_NAME_MAX - The maximum size of a file name.
+# CONFIG_STDIO_BUFFER_SIZE - Size of the buffer to allocate
+#   on fopen. (Only if CONFIG_NFILE_STREAMS > 0)
+# CONFIG_NUNGET_CHARS - Number of characters that can be
+#   buffered by ungetc() (Only if CONFIG_NFILE_STREAMS > 0)
+# CONFIG_PREALLOC_MQ_MSGS - The number of pre-allocated message
+#   structures.  The system manages a pool of preallocated
+#   message structures to minimize dynamic allocations
+# CONFIG_MQ_MAXMSGSIZE - Message structures are allocated with
+#   a fixed payload size given by this settin (does not include
+#   other message structure overhead.
+# CONFIG_MAX_WDOGPARMS - Maximum number of parameters that
+#   can be passed to a watchdog handler
+# CONFIG_PREALLOC_WDOGS - The number of pre-allocated watchdog
+#   structures.  The system manages a pool of preallocated
+#   watchdog structures to minimize dynamic allocations
+# CONFIG_PREALLOC_TIMERS - The number of pre-allocated POSIX
+#   timer structures.  The system manages a pool of preallocated
+#   timer structures to minimize dynamic allocations.  Set to
+#   zero for all dynamic allocations.
+#
+CONFIG_MAX_TASKS=8
+CONFIG_MAX_TASK_ARGS=4
+CONFIG_NPTHREAD_KEYS=0
+CONFIG_NFILE_DESCRIPTORS=0
+CONFIG_NFILE_STREAMS=0
+CONFIG_NAME_MAX=32
+CONFIG_STDIO_BUFFER_SIZE=0
+CONFIG_NUNGET_CHARS=0
+CONFIG_PREALLOC_MQ_MSGS=0
+CONFIG_MQ_MAXMSGSIZE=0
+CONFIG_MAX_WDOGPARMS=2
+CONFIG_PREALLOC_WDOGS=4
+CONFIG_PREALLOC_TIMERS=0
+
+#
+# TCP/IP and UDP support via uIP
+# CONFIG_NET - Enable or disable all network features
+# CONFIG_NET_IPv6 - Build in support for IPv6
+# CONFIG_NSOCKET_DESCRIPTORS - Maximum number of socket descriptors per task/thread.
+# CONFIG_NET_SOCKOPTS - Enable or disable support for socket options
+# CONFIG_NET_BUFSIZE - uIP buffer size
+# CONFIG_NET_TCP - TCP support on or off
+# CONFIG_NET_TCP_CONNS - Maximum number of TCP connections (all tasks)
+# CONFIG_NET_TCP_READAHEAD_BUFSIZE - Size of TCP read-ahead buffers
+# CONFIG_NET_NTCP_READAHEAD_BUFFERS - Number of TCP read-ahead buffers (may be zero)
+# CONFIG_NET_MAX_LISTENPORTS - Maximum number of listening TCP ports (all tasks)
+# CONFIG_NET_UDP - UDP support on or off
+# CONFIG_NET_UDP_CHECKSUMS - UDP checksums on or off
+# CONFIG_NET_UDP_CONNS - The maximum amount of concurrent UDP connections
+# CONFIG_NET_ICMP - ICMP ping support on or off
+# CONFIG_NET_PINGADDRCONF - Use "ping" packet for setting IP address
+# CONFIG_NET_STATISTICS - uIP statistics on or off
+# CONFIG_NET_RECEIVE_WINDOW - The size of the advertised receiver's window
+# CONFIG_NET_ARPTAB_SIZE - The size of the ARP table
+# CONFIG_NET_BROADCAST - Broadcast support
+# CONFIG_NET_LLH_LEN - The link level header length
+# CONFIG_NET_FWCACHE_SIZE - number of packets to remember when looking for duplicates
+CONFIG_NET=n
+CONFIG_NET_IPv6=n
+CONFIG_NSOCKET_DESCRIPTORS=0
+CONFIG_NET_SOCKOPTS=y
+CONFIG_NET_BUFSIZE=420
+CONFIG_NET_TCP=n
+CONFIG_NET_TCP_CONNS=40
+CONFIG_NET_MAX_LISTENPORTS=40
+CONFIG_NET_UDP=n
+CONFIG_NET_UDP_CHECKSUMS=y
+#CONFIG_NET_UDP_CONNS=10
+CONFIG_NET_ICMP=n
+#CONFIG_NET_PINGADDRCONF=0
+CONFIG_NET_STATISTICS=y
+#CONFIG_NET_RECEIVE_WINDOW=
+#CONFIG_NET_ARPTAB_SIZE=8
+CONFIG_NET_BROADCAST=n
+#CONFIG_NET_LLH_LEN=14
+#CONFIG_NET_FWCACHE_SIZE=2
+
+#
+# UIP Network Utilities
+# CONFIG_NET_DHCP_LIGHT - Reduces size of DHCP
+# CONFIG_NET_RESOLV_ENTRIES - Number of resolver entries
+CONFIG_NET_DHCP_LIGHT=n
+CONFIG_NET_RESOLV_ENTRIES=4
+
+#
+# Settings for examples/nsh
+CONFIG_EXAMPLES_NSH_TELNET=n
+CONFIG_EXAMPLES_NSH_IOBUFFER_SIZE=512
+CONFIG_EXAMPLES_NSH_CMD_SIZE=40
+CONFIG_EXAMPLES_NSH_STACKSIZE=4096
+CONFIG_EXAMPLES_NSH_DHCPC=n
+CONFIG_EXAMPLES_NSH_NOMAC=n
+CONFIG_EXAMPLES_NSH_IPADDR=(10<<24|0<<16|0<<8|2)
+CONFIG_EXAMPLES_NSH_DRIPADDR=(10<<24|0<<16|0<<8|1)
+CONFIG_EXAMPLES_NSH_NETMASK=(255<<24|255<<16|255<<8|0)
+
+#
+# Stack and heap information
+#
+# CONFIG_BOOT_FROM_FLASH - Some configurations support XIP
+#   operation from FLASH.
+# CONFIG_CUSTOM_STACK - The up_ implementation will handle
+#   all stack operations outside of the nuttx model.
+# CONFIG_STACK_POINTER - The initial stack pointer
+# CONFIG_PROC_STACK_SIZE - The size of the initial stack
+# CONFIG_PTHREAD_STACK_MIN - Minimum pthread stack size
+# CONFIG_PTHREAD_STACK_DEFAULT - Default pthread stack size
+# CONFIG_HEAP_BASE - The beginning of the heap
+# CONFIG_HEAP_SIZE - The size of the heap
+#
+CONFIG_BOOT_FROM_FLASH=n
+CONFIG_CUSTOM_STACK=n
+CONFIG_PROC_STACK_SIZE=1024
+CONFIG_PTHREAD_STACK_MIN=
+CONFIG_PTHREAD_STACK_DEFAULT=
+CONFIG_HEAP_SIZE=32768
+CONFIG_HEAP_BASE=CONFIG_DRAM_SIZE-CONFIG_HEAP_SIZE
diff --git a/nuttx/configs/z80sim/include/README.txt b/nuttx/configs/z80sim/include/README.txt
new file mode 100644
index 000000000..4af1b2ad2
--- /dev/null
+++ b/nuttx/configs/z80sim/include/README.txt
@@ -0,0 +1 @@
+This directory contains header files unique to the z80 simulation
diff --git a/nuttx/configs/z80sim/include/board.h b/nuttx/configs/z80sim/include/board.h
new file mode 100644
index 000000000..85edae22c
--- /dev/null
+++ b/nuttx/configs/z80sim/include/board.h
@@ -0,0 +1,51 @@
+/************************************************************
+ * board/board.h
+ *
+ *   Copyright (C) 2007, 2008 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ************************************************************/
+
+#ifndef __ARCH_BOARD_BOARD_H
+#define __ARCH_BOARD_BOARD_H
+
+/************************************************************
+ * Included Files
+ ************************************************************/
+
+/************************************************************
+ * Definitions
+ ************************************************************/
+
+/************************************************************
+ * Inline Functions
+ ************************************************************/
+
+#endif  /* __ARCH_BOARD_BOARD_H */
diff --git a/nuttx/configs/z80sim/setenv.sh b/nuttx/configs/z80sim/setenv.sh
new file mode 100755
index 000000000..69614aefe
--- /dev/null
+++ b/nuttx/configs/z80sim/setenv.sh
@@ -0,0 +1,45 @@
+#!/bin/sh
+# setenv.sh
+#
+#   Copyright (C) 2007 Gregory Nutt. All rights reserved.
+#   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions
+# are met:
+#
+# 1. Redistributions of source code must retain the above copyright
+#    notice, this list of conditions and the following disclaimer.
+# 2. Redistributions in binary form must reproduce the above copyright
+#    notice, this list of conditions and the following disclaimer in
+#    the documentation and/or other materials provided with the
+#    distribution.
+# 3. Neither the name Gregory Nutt nor the names of its contributors may be
+#    used to endorse or promote products derived from this software
+#    without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+# FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+# COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+# INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+# BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+# OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+# AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+# ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+# POSSIBILITY OF SUCH DAMAGE.
+#
+
+if [ "$(basename $0)" = "setenv" ] ; then
+  echo "You must source this script, not run it!" 1>&2
+  exit 1
+fi
+
+if [ -z ${PATH_ORIG} ]; then export PATH_ORIG=${PATH}; fi
+
+export SDCC_BIN=/usr/local/bin
+export PATH=${SDCC_BIN}:/sbin:/usr/sbin:${PATH_ORIG}
+
+echo "PATH : ${PATH}"
diff --git a/nuttx/configs/z80sim/src/Makefile b/nuttx/configs/z80sim/src/Makefile
new file mode 100644
index 000000000..24226f2f9
--- /dev/null
+++ b/nuttx/configs/z80sim/src/Makefile
@@ -0,0 +1,79 @@
+############################################################
+# Makefile
+#
+#   Copyright (C) 2007 Gregory Nutt. All rights reserved.
+#   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions
+# are met:
+#
+# 1. Redistributions of source code must retain the above copyright
+#    notice, this list of conditions and the following disclaimer.
+# 2. Redistributions in binary form must reproduce the above copyright
+#    notice, this list of conditions and the following disclaimer in
+#    the documentation and/or other materials provided with the
+#    distribution.
+# 3. Neither the name Gregory Nutt nor the names of its contributors may be
+#    used to endorse or promote products derived from this software
+#    without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+# FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+# COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+# INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+# BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+# OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+# AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+# ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+# POSSIBILITY OF SUCH DAMAGE.
+#
+############################################################
+
+-include $(TOPDIR)/Make.defs
+
+MKDEP 		= $(TOPDIR)/tools/mkdeps.sh
+CFLAGS		+= -I$(TOPDIR)/sched
+
+ASRCS		= z80_lowputc$(ASMEXT) 
+AOBJS		= $(ASRCS:$(ASMEXT)=$(OBJEXT))
+CSRCS		= z80_decodeirq.c z80_irq.c z80_serial.c z80_timerisr.c
+COBJS		= $(CSRCS:.c=$(OBJEXT))
+
+SRCS		= $(ASRCS) $(CSRCS)
+OBJS		= $(AOBJS) $(COBJS)
+
+CFLAGS		+= -I $(TOPDIR)/arch/$(CONFIG_ARCH)/src
+
+all: libboard$(LIBEXT)
+
+$(AOBJS): %$(OBJEXT): %$(ASMEXT)
+	$(CC) -c $(CFLAGS) -D__ASSEMBLY__ $< -o $@
+
+$(COBJS) $(LINKOBJS): %$(OBJEXT): %.c
+	$(CC) -c $(CFLAGS) $< -o $@
+
+libboard$(LIBEXT): $(OBJS)
+	( for obj in $(OBJS) ; do \
+		$(AR) $@ $${obj} || \
+			{ echo "$(AR) $@ $obj FAILED!" ; exit 1 ; } ; \
+	done ; )
+
+.depend: Makefile $(SRCS)
+	$(MKDEP) $(CC) -- $(CFLAGS) -- $(SRCS) >Make.dep
+	touch $@
+
+depend: .depend
+
+clean:
+	rm -f libboard$(LIBEXT)
+	rm -f *.asm *.rel *.lst *.rst *.sym *.adb *.lnk *.map *.mem *.ihx *.hex *~
+	if [ ! -z "$(OBJEXT)" ]; then rm -f *$(OBJEXT); fi
+
+distclean: clean
+	rm -f Make.dep .depend
+
+-include Make.dep
diff --git a/nuttx/configs/z80sim/src/README.txt b/nuttx/configs/z80sim/src/README.txt
new file mode 100644
index 000000000..13c1e3e58
--- /dev/null
+++ b/nuttx/configs/z80sim/src/README.txt
@@ -0,0 +1 @@
+This directory contains drivers unique to the z80 simulation
diff --git a/nuttx/configs/z80sim/src/z80_decodeirq.c b/nuttx/configs/z80sim/src/z80_decodeirq.c
new file mode 100644
index 000000000..d4faf0f89
--- /dev/null
+++ b/nuttx/configs/z80sim/src/z80_decodeirq.c
@@ -0,0 +1,119 @@
+/********************************************************************************
+ * z80/z80_decodeirq.c
+ *
+ *   Copyright (C) 2007, 2008 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ********************************************************************************/
+
+/********************************************************************************
+ * Included Files
+ ********************************************************************************/
+
+#include <nuttx/config.h>
+#include <sys/types.h>
+#include <nuttx/irq.h>
+#include <nuttx/arch.h>
+#include <assert.h>
+#include <debug.h>
+#include "up_arch.h"
+#include "os_internal.h"
+#include "up_internal.h"
+
+/********************************************************************************
+ * Definitions
+ ********************************************************************************/
+
+/********************************************************************************
+ * Public Data
+ ********************************************************************************/
+
+/********************************************************************************
+ * Private Data
+ ********************************************************************************/
+
+/********************************************************************************
+ * Private Functions
+ ********************************************************************************/
+
+/********************************************************************************
+ * Public Funtions
+ ********************************************************************************/
+
+void up_decodeirq(uint16* regs)
+{
+#ifdef CONFIG_SUPPRESS_INTERRUPTS
+  lib_lowprintf("Unexpected IRQ\n");
+  current_regs = regs;
+  PANIC(OSERR_ERREXCEPTION);
+#else
+  /* Decode the interrupt.  First, fetch the interrupt id register. */
+
+  uint16 irqentry = getreg16(DM320_INTC_IRQENTRY0);
+
+  /* The irqentry value is an offset into a table.  Zero means no interrupt. */
+
+  if (irqentry != 0)
+    {
+      /* If non-zero, then we can map the table offset into an IRQ number */
+
+      int irq = (irqentry >> 2) - 1;
+
+      /* Verify that the resulting IRQ number is valie */
+
+      if ((unsigned)irq < NR_IRQS)
+        {
+          /* Mask and acknowledge the interrupt */
+
+          up_maskack_irq(irq);
+
+          /* Current regs non-zero indicates that we are processing an interrupt;
+           * current_regs is also used to manage interrupt level context switches.
+           */
+
+          current_regs = regs;
+
+          /* Deliver the IRQ */
+
+          irq_dispatch(irq, regs);
+
+          /* Indicate that we are no long in an interrupt handler */
+
+          current_regs = NULL;
+
+          /* Unmask the last interrupt (global interrupts are still
+           * disabled.
+           */
+
+          up_enable_irq(irq);
+        }
+    }
+#endif
+}
diff --git a/nuttx/configs/z80sim/src/z80_irq.c b/nuttx/configs/z80sim/src/z80_irq.c
new file mode 100644
index 000000000..3c3443663
--- /dev/null
+++ b/nuttx/configs/z80sim/src/z80_irq.c
@@ -0,0 +1,110 @@
+/****************************************************************************
+ * z80/z80_irq.c
+ *
+ *   Copyright (C) 2007 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name Gregory Nutt nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+#include <sys/types.h>
+#include <nuttx/irq.h>
+#include "up_arch.h"
+#include "os_internal.h"
+#include "up_internal.h"
+
+/****************************************************************************
+ * Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Data
+ ****************************************************************************/
+
+uint32 *current_regs;
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Funtions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: up_irqinitialize
+ ****************************************************************************/
+
+void up_irqinitialize(void)
+{
+  /* currents_regs is non-NULL only while processing an interrupt */
+
+  current_regs = NULL;
+
+  /* And finally, enable interrupts */
+
+#ifndef CONFIG_SUPPRESS_INTERRUPTS
+  irqrestore(TRUE);
+#endif
+}
+
+/****************************************************************************
+ * Name: up_disable_irq
+ *
+ * Description:
+ *   Disable the IRQ specified by 'irq'
+ *
+ ****************************************************************************/
+
+void up_disable_irq(int irq)
+{
+  irqrestore(FALSE);
+}
+
+/****************************************************************************
+ * Name: up_enable_irq
+ *
+ * Description:
+ *   Enable the IRQ specified by 'irq'
+ *
+ ****************************************************************************/
+
+void up_enable_irq(int irq)
+{
+ irqrestore(TRUE);
+}
diff --git a/nuttx/configs/z80sim/src/z80_serial.c b/nuttx/configs/z80sim/src/z80_serial.c
new file mode 100644
index 000000000..73bba4932
--- /dev/null
+++ b/nuttx/configs/z80sim/src/z80_serial.c
@@ -0,0 +1,334 @@
+/****************************************************************************
+ * z80/z80_serial.c
+ *
+ *   Copyright (C) 2007, 2008 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <sys/types.h>
+#include <unistd.h>
+#include <semaphore.h>
+#include <string.h>
+#include <errno.h>
+#include <debug.h>
+
+#include <nuttx/irq.h>
+#include <nuttx/arch.h>
+#include <nuttx/serial.h>
+#include <arch/serial.h>
+
+#include "up_arch.h"
+#include "os_internal.h"
+#include "up_internal.h"
+
+#if CONFIG_NFILE_DESCRIPTORS > 0
+
+/****************************************************************************
+ * Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Types
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Function Prototypes
+ ****************************************************************************/
+
+static int     up_setup(struct uart_dev_s *dev);
+static void    up_shutdown(struct uart_dev_s *dev);
+static int     up_interrupt(int irq, void *context);
+static int     up_ioctl(struct file *filep, int cmd, unsigned long arg);
+static int     up_receive(struct uart_dev_s *dev, uint32 *status);
+static void    up_rxint(struct uart_dev_s *dev, boolean enable);
+static boolean up_rxfifonotempty(struct uart_dev_s *dev);
+static void    up_send(struct uart_dev_s *dev, int ch);
+static void    up_txint(struct uart_dev_s *dev, boolean enable);
+static boolean up_txfifonotfull(struct uart_dev_s *dev);
+static boolean up_txfifoempty(struct uart_dev_s *dev);
+
+/****************************************************************************
+ * Private Variables
+ ****************************************************************************/
+
+struct uart_ops_s g_uart_ops =
+{
+  .setup          = up_setup,
+  .shutdown       = up_shutdown,
+  .handler        = up_interrupt,
+  .ioctl          = up_ioctl,
+  .receive        = up_receive,
+  .rxint          = up_rxint,
+  .rxfifonotempty = up_rxfifonotempty,
+  .send           = up_send,
+  .txint          = up_txint,
+  .txfifonotfull  = up_txfifonotfull,
+  .txfifoempty    = up_txfifoempty,
+};
+
+/* I/O buffers */
+
+static char g_uartrxbuffer[CONFIG_UART0_RXBUFSIZE];
+static char g_uarttxbuffer[CONFIG_UART0_TXBUFSIZE];
+
+/* This describes the state of the fake UART port. */
+
+static uart_dev_t g_uartport =
+{
+  .irq      = DM320_IRQ_UART0,
+  .recv     =
+  {
+    .size   = CONFIG_UART0_RXBUFSIZE,
+    .buffer = g_uart0rxbuffer,
+  },
+  .xmit     =
+  {
+    .size   = CONFIG_UART0_TXBUFSIZE,
+    .buffer = g_uart0txbuffer,
+  },
+  .ops      = &g_uart_ops,
+  .priv     = NULL,
+};
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: up_setup
+ *
+ * Description:
+ *   Configure the UART baud, bits, parity, fifos, etc. This
+ *   method is called the first time that the serial port is
+ *   opened.
+ *
+ ****************************************************************************/
+
+static int up_setup(struct uart_dev_s *dev)
+{
+  return OK;
+}
+
+/****************************************************************************
+ * Name: up_shutdown
+ *
+ * Description:
+ *   Disable the UART.  This method is called when the serial
+ *   port is closed
+ *
+ ****************************************************************************/
+
+static void up_shutdown(struct uart_dev_s *dev)
+{
+}
+
+/****************************************************************************
+ * Name: up_interrupt
+ *
+ * Description:
+ *   This is the UART interrupt handler.  It will be invoked
+ *   when an interrupt received on the 'irq'  It should call
+ *   uart_transmitchars or uart_receivechar to perform the
+ *   appropriate data transfers.  The interrupt handling logic\
+ *   must be able to map the 'irq' number into the approprite
+ *   uart_dev_s structure in order to call these functions.
+ *
+ ****************************************************************************/
+
+static int up_interrupt(int irq, void *context)
+{
+  return OK;
+}
+
+/****************************************************************************
+ * Name: up_ioctl
+ *
+ * Description:
+ *   All ioctl calls will be routed through this method
+ *
+ ****************************************************************************/
+
+static int up_ioctl(struct file *filep, int cmd, unsigned long arg)
+{
+  *get_errno_ptr() = ENOTTY;
+  return ERROR;
+}
+
+/****************************************************************************
+ * Name: up_receive
+ *
+ * Description:
+ *   Called (usually) from the interrupt level to receive one
+ *   character from the UART.  Error bits associated with the
+ *   receipt are provided in the the return 'status'.
+ *
+ ****************************************************************************/
+
+static int up_receive(struct uart_dev_s *dev, uint32 *status)
+{
+  uint8 ch = up_lowgetc();
+  *status = 0;
+  return ch;
+}
+
+/****************************************************************************
+ * Name: up_rxint
+ *
+ * Description:
+ *   Call to enable or disable RX interrupts
+ *
+ ****************************************************************************/
+
+static void up_rxint(struct uart_dev_s *dev, boolean enable)
+{
+}
+
+/****************************************************************************
+ * Name: up_rxfifonotempty
+ *
+ * Description:
+ *   Return TRUE if the receive fifo is not empty
+ *
+ ****************************************************************************/
+
+static boolean up_rxfifonotempty(struct uart_dev_s *dev)
+{
+  return TRUE;
+}
+
+/****************************************************************************
+ * Name: up_send
+ *
+ * Description:
+ *   This method will send one byte on the UART
+ *
+ ****************************************************************************/
+
+static void up_send(struct uart_dev_s *dev, int ch)
+{
+  up_lowputc(ch);
+}
+
+/****************************************************************************
+ * Name: up_txint
+ *
+ * Description:
+ *   Call to enable or disable TX interrupts
+ *
+ ****************************************************************************/
+
+static void up_txint(struct uart_dev_s *dev, boolean enable)
+{
+}
+
+/****************************************************************************
+ * Name: up_txfifonotfull
+ *
+ * Description:
+ *   Return TRUE if the tranmsit fifo is not full
+ *
+ ****************************************************************************/
+
+static boolean up_txfifonotfull(struct uart_dev_s *dev)
+{
+  return TRUE;
+}
+
+/****************************************************************************
+ * Name: up_txfifoempty
+ *
+ * Description:
+ *   Return TRUE if the transmit fifo is empty
+ *
+ ****************************************************************************/
+
+static boolean up_txfifoempty(struct uart_dev_s *dev)
+{
+  return FALSE;
+}
+
+/****************************************************************************
+ * Public Funtions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: up_serialinit
+ *
+ * Description:
+ *   Performs the low level UART initialization early in 
+ *   debug so that the serial console will be available
+ *   during bootup.  This must be called before up_serialinit.
+ *
+ ****************************************************************************/
+
+void up_earlyserialinit(void)
+{
+}
+
+/****************************************************************************
+ * Name: up_serialinit
+ *
+ * Description:
+ *   Register serial console and serial ports.  This assumes
+ *   that up_earlyserialinit was called previously.
+ *
+ ****************************************************************************/
+
+void up_serialinit(void)
+{
+  (void)uart_register("/dev/console", &g_uartport);
+  (void)uart_register("/dev/ttyS0", &g_uartport);
+}
+#endif /* CONFIG_NFILE_DESCRIPTORS > 0 */
+
+/****************************************************************************
+ * Name: up_putc
+ *
+ * Description:
+ *   Provide priority, low-level access to support OS debug
+ *   writes
+ *
+ ****************************************************************************/
+
+int up_putc(int ch)
+{
+  up_lowputc(ch);
+}
+
+
+
+
diff --git a/nuttx/configs/z80sim/src/z80_timerisr.c b/nuttx/configs/z80sim/src/z80_timerisr.c
new file mode 100644
index 000000000..603a66c91
--- /dev/null
+++ b/nuttx/configs/z80sim/src/z80_timerisr.c
@@ -0,0 +1,153 @@
+/************************************************************
+ * dm320/dm320_timerisr.c
+ *
+ *   Copyright (C) 2007 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name Gregory Nutt nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ************************************************************/
+
+/************************************************************
+ * Included Files
+ ************************************************************/
+
+#include <nuttx/config.h>
+#include <sys/types.h>
+#include <debug.h>
+#include <nuttx/arch.h>
+#include "clock_internal.h"
+#include "up_internal.h"
+#include "up_arch.h"
+
+/************************************************************
+ * Definitions
+ ************************************************************/
+
+/* DM320 Timers
+ *
+ * Each of the general-purpose timers can run in one of two modes:  one-
+ * shot mode and free-run mode.  In one-shot mode, an interrupt only 
+ * occurs once and then the timer must be explicitly reset to begin the 
+ * timing operation again.  In free-run mode, when the timer generates an 
+ * interrupt, the timer counter is automatically reloaded to start the count 
+ * operation again.  Use the bit field MODE in TMMDx to configure the 
+ * timer for one-shot more or free-run mode. The bit field MODE in TMMDx
+ * also allows you to stop the timer.
+ * 
+ * Either the ARM clock divided by 2 (CLK_ARM/2) or an external clock 
+ * connected to the M27XI pin can be selected as the clock source of the 
+ * timer.
+ *
+ * The actual clock frequency used in the timer count operation is the input 
+ * clock divided by: 1 plus the value set in the bit field PRSCL of the 
+ * register TMPRSCLx (10 bits).  The timer expires when it reaches the 
+ * value set in the bit field DIV of the register TMDIVx (16 bits) plus 1. 
+ * PRSCL+1 is the source clock frequency divide factor and DIV+1 is the 
+ * timer count value.  The frequency of a timer interrupt is given by the 
+ * following equation:
+ *
+ * Interrupt Frequency = (Source Clock Frequency) / (PRSCL+1) / (DIV+1)
+ */
+
+/* System Timer
+ *
+ * Timer0 is dedicated as the system timer.  The rate of system timer
+ * interrupts is assumed to to 10MS per tick / 100Hz. The following
+ * register settings are used for timer 0
+ *
+ * System clock formula:
+ *   Interrupt Frequency = (Source Clock Frequency) / (PRSCL+1) / (DIV+1)
+ *   Source Clock Frequency = 27MHz  (PLL clock)
+ *   DIV                    = 26,999 (Yields 1Khz timer clock)
+ *   PRSCL                  = 9      (Produces 100Hz interrupts)
+ */
+
+#define DM320_TMR0_MODE  DM320_TMR_MODE_FREERUN /* Free running */
+#define DM320_TMR0_DIV   26999                  /* (see above) */
+#define DM320_TMR0_PRSCL 9                      /* (see above) */
+
+/************************************************************
+ * Private Types
+ ************************************************************/
+
+/************************************************************
+ * Private Function Prototypes
+ ************************************************************/
+
+/************************************************************
+ * Global Functions
+ ************************************************************/
+
+/************************************************************
+ * Function:  up_timerisr
+ *
+ * Description:
+ *   The timer ISR will perform a variety of services for
+ *   various portions of the systems.
+ *
+ ************************************************************/
+
+int up_timerisr(int irq, uint32 *regs)
+{
+   /* Process timer interrupt */
+
+   sched_process_timer();
+   return 0;
+}
+
+/************************************************************
+ * Function:  up_timerinit
+ *
+ * Description:
+ *   This function is called during start-up to initialize
+ *   the timer interrupt.
+ *
+ ************************************************************/
+
+void up_timerinit(void)
+{
+  up_disable_irq(DM320_IRQ_SYSTIMER);
+
+  /* Start timer0 running so that an interrupt is generated at
+   * the rate MSEC_PER_TICK.
+   */
+
+  putreg16(DM320_TMR0_PRSCL, DM320_TIMER0_TMPRSCL); /* Timer 0 Prescalar */
+  putreg16(DM320_TMR0_DIV, DM320_TIMER0_TMDIV);     /* Timer 0 Divisor (count) */
+
+  /* Start the timer */
+
+  putreg16(DM320_TMR0_MODE, DM320_TIMER0_TMMD); /* Timer 0 Mode */
+
+  /* Attach and enable the timer interrupt */
+
+  irq_attach(DM320_IRQ_SYSTIMER, (xcpt_t)up_timerisr);
+  up_enable_irq(DM320_IRQ_SYSTIMER);
+}
+