diff --git a/arch/sh/src/m16c/Make.defs b/arch/sh/src/m16c/Make.defs
index fe28a2dfda8..ceba5fd7687 100644
--- a/arch/sh/src/m16c/Make.defs
+++ b/arch/sh/src/m16c/Make.defs
@@ -45,7 +45,7 @@ CMN_CSRCS	= up_allocateheap.c up_assert.c up_blocktask.c \
 CHIP_ASRCS	= m16c_vectors.S
 #CHIP_CSRCS	= m16c_initialstate.c m16c_copystate.c m16c_lowputc.c m16c_irq.c \
 #		  m16c_timerisr.c m16c_serial.c
-CHIP_CSRCS	= m16c_initialstate.c m16c_copystate.c
+CHIP_CSRCS	= m16c_initialstate.c m16c_copystate.c m16c_irq.c
 
 ifneq ($(CONFIG_DISABLE_SIGNALS),y)
 CHIP_CSRCS	+= m16c_schedulesigaction.c m16c_sigdeliver.c
diff --git a/arch/sh/src/m16c/m16c_irq.c b/arch/sh/src/m16c/m16c_irq.c
new file mode 100644
index 00000000000..beac525d4a5
--- /dev/null
+++ b/arch/sh/src/m16c/m16c_irq.c
@@ -0,0 +1,127 @@
+/****************************************************************************
+ * arch/sh/src/m16c/m16c_irq.c
+ *
+ *   Copyright (C) 2009 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 Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Data
+ ****************************************************************************/
+
+/* This holds a references to the current interrupt level register storage
+ * structure.  If is non-NULL only during interrupt processing.
+ */
+
+uint32 *current_regs; /* Actually a pointer to the beginning or a ubyte array */
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: up_irqinitialize
+ ****************************************************************************/
+
+void up_irqinitialize(void)
+{
+  current_regs = NULL;
+  
+  /* And finally, enable interrupts */
+
+#ifndef CONFIG_SUPPRESS_INTERRUPTS
+  asm("fset i");
+#endif
+}
+
+/****************************************************************************
+ * Name: up_disable_irq
+ *
+ * Description:
+ *   On many architectures, there are three levels of interrupt enabling: (1)
+ *   at the global level, (2) at the level of the interrupt controller,
+ *   and (3) at the device level.  In order to receive interrupts, they
+ *   must be enabled at all three levels.
+ *
+ *   This function implements disabling of the device specified by 'irq'
+ *   at the interrupt controller level if supported by the architecture
+ *   (irqsave() supports the global level, the device level is hardware
+ *   specific).
+ *
+ ****************************************************************************/
+
+#ifndef CONFIG_ARCH_NOINTC
+void up_disable_irq(int irq)
+{
+  /* There are no ez80 interrupt controller settings to disable IRQs */
+}
+
+/****************************************************************************
+ * Name: up_enable_irq
+ *
+ * Description:
+ *   This function implements enabling of the device specified by 'irq'
+ *   at the interrupt controller level if supported by the architecture
+ *   (irqsave() supports the global level, the device level is hardware
+ *   specific).
+ *
+ ****************************************************************************/
+
+void up_enable_irq(int irq)
+{
+  /* There are no ez80 interrupt controller settings to enable IRQs */
+}
+
+#endif /* CONFIG_ARCH_NOINTC */
diff --git a/configs/skp16c26/ostest/defconfig b/configs/skp16c26/ostest/defconfig
index c194f02f6e5..ffadaa5c73c 100644
--- a/configs/skp16c26/ostest/defconfig
+++ b/configs/skp16c26/ostest/defconfig
@@ -45,6 +45,9 @@
 # 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_ARCH_NOINTC - define if the architecture does not
+#   support an interrupt controller or otherwise cannot support
+#   APIs like up_enable_irq() and up_disable_irq().
 # CONFIG_ENDIAN_BIG - define if big endian (default is little endian)
 # CONFIG_BOARD_LOOPSPERMSEC - for delay loops
 # CONFIG_DRAM_SIZE - Describes the internal SRAM.
@@ -62,6 +65,7 @@ CONFIG_ARCH_CHIP=m16c
 CONFIG_ARCH_CHIP_M30262F8=y
 CONFIG_ARCH_BOARD=skp16c26
 CONFIG_ARCH_BOARD_SKP16C26=y
+CONFIG_ARCH_NOINTC=y
 CONFIG_ENDIAN_BIG=y
 CONFIG_DRAM_SIZE=0x00800
 CONFIG_DRAM_START=0x00400