diff --git a/arch/c5471/include/irq.h b/arch/c5471/include/irq.h
index c6a89e9511a..051848ba506 100644
--- a/arch/c5471/include/irq.h
+++ b/arch/c5471/include/irq.h
@@ -212,7 +212,7 @@ static inline void system_call(swint_t func, int parm1,
      "mov\tr0,%0\n\t"
      "mov\tr1,%1\n\t"
      "mov\tr2,%2\n\t"
-     "mov\tr2,%3\n\t"
+     "mov\tr3,%3\n\t"
      "swi\t0x900001\n\t"
      :
      : "r" ((long)(func)),  "r" ((long)(parm1)),
diff --git a/arch/c5471/src/up_assert.c b/arch/c5471/src/up_assert.c
index 8b70349f47e..49754088a87 100644
--- a/arch/c5471/src/up_assert.c
+++ b/arch/c5471/src/up_assert.c
@@ -42,6 +42,9 @@
 #include <stdlib.h>
 #include <assert.h>
 #include <debug.h>
+#include <nuttx/irq.h>
+#include "os_internal.h"
+#include "up_internal.h"
 
 /************************************************************
  * Definitions
@@ -55,6 +58,21 @@
  * Private Functions
  ************************************************************/
 
+static void _up_assert(int errorcode) /* __attribute__ ((noreturn)) */
+{
+  /* Are we in an interrupt handler or the idle task? */
+
+  if (current_regs || ((_TCB*)g_readytorun.head)->pid == 0)
+    {
+       (void)irqsave();
+        for(;;);
+    }
+  else
+    {
+      exit(errorcode);
+    }
+}
+
 /************************************************************
  * Public Funtions
  ************************************************************/
@@ -67,7 +85,7 @@ void up_assert(const ubyte *filename, int lineno)
 {
   dbg("Assertion failed at file:%s line: %d\n",
       filename, lineno);
-  exit(EXIT_FAILURE);
+  _up_assert(EXIT_FAILURE);
 }
 
 /************************************************************
@@ -78,5 +96,5 @@ void up_assert_code(const ubyte *filename, int lineno, int errorcode)
 {
   dbg("Assertion failed at file:%s line: %d error code: %d\n",
        filename, lineno, errorcode);
-  exit(errorcode);
+  _up_assert(errorcode);
 }
diff --git a/arch/c5471/src/up_doirq.c b/arch/c5471/src/up_doirq.c
index 339b2859661..48cbd3e4ad8 100644
--- a/arch/c5471/src/up_doirq.c
+++ b/arch/c5471/src/up_doirq.c
@@ -41,7 +41,9 @@
 #include <sys/types.h>
 #include <nuttx/irq.h>
 #include <nuttx/arch.h>
+#include <assert.h>
 #include "c5471.h"
+#include "os_internal.h"
 #include "up_internal.h"
 
 /************************************************************
@@ -66,6 +68,9 @@
 
 void up_doirq(int irq, uint32* regs)
 {
+#ifdef CONFIG_SUPPRESS_INTERRUPTS
+  PANIC(OSERR_ERREXCEPTION);
+#else
   if ((unsigned)irq < NR_IRQS)
     {
        /* Mask and acknowledge the interrupt */
@@ -80,4 +85,5 @@ void up_doirq(int irq, uint32* regs)
 
        up_enable_irq(irq);
     }
+#endif
 }
diff --git a/arch/c5471/src/up_idle.c b/arch/c5471/src/up_idle.c
index 46177a3de8f..3ec71e50e03 100644
--- a/arch/c5471/src/up_idle.c
+++ b/arch/c5471/src/up_idle.c
@@ -75,5 +75,12 @@
 
 void up_idle(void)
 {
+#ifdef CONFIG_SUPPRESS_INTERRUPTS
+  /* If the system is idle, then process "fake" timer interrupts.
+   * Hopefully, something will wake up.
+   */
+
+  sched_process_timer();
+#endif
 }
 
diff --git a/arch/c5471/src/up_internal.h b/arch/c5471/src/up_internal.h
index 7563a15fcd3..0c03967c044 100644
--- a/arch/c5471/src/up_internal.h
+++ b/arch/c5471/src/up_internal.h
@@ -47,7 +47,7 @@
 /* Bring-up debug configurations */
 
 #define CONFIG_SUPPRESS_INTERRUPTS  1 /* Do not enable interrupts */
-#define CONFIG_SUPPRESS_UART_CONFIG 1 /* Do not reconfig UART */
+#undef  CONFIG_SUPPRESS_UART_CONFIG   /* Do not reconfig UART */
 
 /************************************************************
  * Public Types
diff --git a/arch/c5471/src/up_irq.c b/arch/c5471/src/up_irq.c
index 6b981c99a53..fabd47b26c4 100644
--- a/arch/c5471/src/up_irq.c
+++ b/arch/c5471/src/up_irq.c
@@ -136,6 +136,7 @@ static inline void up_vectorinitialize(void)
   up_vector_t *src  = g_vectorinittab;
   up_vector_t *dest = (up_vector_t*)&_svectors;
   int i;
+
   for (i = 0; i < NVECTORS; i++)
     {
       *dest++ = *src++;
diff --git a/arch/c5471/src/up_serial.c b/arch/c5471/src/up_serial.c
index 7bd90ef1117..faaf7aeed2f 100644
--- a/arch/c5471/src/up_serial.c
+++ b/arch/c5471/src/up_serial.c
@@ -96,8 +96,8 @@ struct up_dev_s
   ubyte                xmit_fifo_size;	/* Size of transmit FIFO */
   ubyte                irq;		/* IRQ associated with
 					 * this UART */
-  boolean              parity;		/* 0=none, 1=odd, 2=even */
-  boolean              bits;		/* Number of bits (7 or 8) */
+  ubyte                parity;		/* 0=none, 1=odd, 2=even */
+  ubyte                bits;		/* Number of bits (7 or 8) */
 #ifdef CONFIG_UART_HWFLOWCONTROL
   boolean              flowcontrol;	/* TRUE: Hardware flow control
 					 * is enabled. */
@@ -1140,3 +1140,4 @@ int up_putc(int ch)
   up_restoreuartint(&CONSOLE_DEV, ier);
   return ch;
 }
+
diff --git a/arch/c5471/src/up_vectors.S b/arch/c5471/src/up_vectors.S
index 110fcce6934..07aab9272a7 100644
--- a/arch/c5471/src/up_vectors.S
+++ b/arch/c5471/src/up_vectors.S
@@ -141,7 +141,7 @@ up_vectorirq:
 					 * no pending interrupt */
 .Lhaveirq:
 #endif
-	/* Then call the data abort handler with interrupt disabled.
+	/* Then call the IRQ handler with interrupt disabled.
 	 * rq_dispatch(int irq, struct xcptcontext *xcp)
 	 */
 
@@ -297,7 +297,7 @@ up_vectorprefetch:
 	add	r0, sp, #(4*REG_PC)	/* Offset to pc, cpsr storage */
 	stmia	r0, {r1, r2}
 
-	/* Then call the data abort handler with interrupt disabled.
+	/* Then call the prefetch abort handler with interrupt disabled.
 	 * void up_prefetchabort(struct xcptcontext *xcp)
 	 */
 
@@ -352,7 +352,7 @@ up_vectorundefinsn:
 	add	r0, sp, #(4*REG_PC)	/* Offset to pc, cpsr storage */
 	stmia	r0, {r1, r2}
 
-	/* Then call the data abort handler with interrupt disabled.
+	/* Then call the undef insn handler with interrupt disabled.
 	 * void up_undefinedinsn(struct xcptcontext *xcp)
 	 */
 
diff --git a/arch/sim/src/up_idle.c b/arch/sim/src/up_idle.c
index b40b2e3d87b..3ca8c094a47 100644
--- a/arch/sim/src/up_idle.c
+++ b/arch/sim/src/up_idle.c
@@ -75,8 +75,8 @@
 
 void up_idle(void)
 {
-  /* If the system, then process timer interrupts.  Hopefully
-   * something will wake up.
+  /* If the system is idle, then process "fake" timer interrupts.
+   * Hopefully, something will wake up.
    */
 
   sched_process_timer();