diff --git a/arch/sim/src/Makefile b/arch/sim/src/Makefile
index 70b570e321..f9eaeac498 100644
--- a/arch/sim/src/Makefile
+++ b/arch/sim/src/Makefile
@@ -51,12 +51,14 @@ CSRCS		+= up_blockdevice.c up_deviceimage.c
 endif
 ifeq ($(CONFIG_NET_UIP),y)
 CSRCS		+= up_uipdriver.c
+SPECSRCS	+= up_tapdev.c
 endif
 
 COBJS		= $(CSRCS:.c=$(OBJEXT))
+SPECOBJS	= $(SPECSRCS:.c=$(OBJEXT))
 
-SRCS		= $(ASRCS) $(CSRCS)
-OBJS		= $(AOBJS) $(COBJS)
+SRCS		= $(ASRCS) $(CSRCS) $(SPECSRCS)
+OBJS		= $(AOBJS) $(COBJS) $(SPECOBJS)
 
 LDFLAGS		= $(ARCHSCRIPT)
 EXTRA_LIBS	= -lc
@@ -77,6 +79,9 @@ $(AOBJS): %$(OBJEXT): %.S
 $(COBJS) $(LINKOBJS): %$(OBJEXT): %.c
 	$(CC) -c $(CFLAGS) $< -o $@
 
+$(SPECOBJS): %$(OBJEXT): %.c
+	$(CC) -c $(HOSTCFLAGS) $< -o $@
+
 libarch$(LIBEXT): $(OBJS)
 	( for obj in $(OBJS) ; do \
 		$(AR) $@ $${obj} || \
diff --git a/arch/sim/src/up_internal.h b/arch/sim/src/up_internal.h
index ab3df0ff52..f2a7512a02 100644
--- a/arch/sim/src/up_internal.h
+++ b/arch/sim/src/up_internal.h
@@ -107,9 +107,18 @@ extern void up_registerblockdevice(void);
 
 extern char *up_deviceimage(void);
 
+/* up_tapdev.c ************************************************************/
+
+#ifdef CONFIG_NET_UIP 
+extern unsigned long up_getwalltime( void );
+extern void tapdev_init(void);
+extern unsigned int tapdev_read(char *buf, unsigned int buflen);
+extern void tapdev_send(char *buf, unsigned int buflen);
+#endif
+
 /* up_uipdriver.c *********************************************************/
 
-#ifdef CONFIG_NET_UIP
+#ifdef CONFIG_NET_UIP 
 extern int uipdriver_init(void);
 extern void uipdriver_loop(void);
 #endif
diff --git a/arch/sim/src/up_tapdev.c b/arch/sim/src/up_tapdev.c
new file mode 100644
index 0000000000..e033048468
--- /dev/null
+++ b/arch/sim/src/up_tapdev.c
@@ -0,0 +1,205 @@
+/****************************************************************************
+ * up_tapdev.c
+ *
+ *   Copyright (C) 2007 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Based on code from uIP which also has a BSD-like license:
+ *
+ *   Copyright (c) 2001, Adam Dunkels.
+ *   All rights reserved.
+ *
+ * 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 <sys/ioctl.h>
+#include <sys/socket.h>
+#include <sys/types.h>
+#include <sys/time.h>
+#include <sys/uio.h>
+#include <sys/socket.h>
+
+#include <fcntl.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <string.h>
+
+#if 0
+#include "uip/uip.h"
+#include <net/uip/uip-arch.h>
+#include <net/uip/uip-arp.h>
+#endif
+
+#ifdef linux
+# include <sys/ioctl.h>
+# include <linux/if.h>
+# include <linux/if_tun.h>
+# define DEVTAP "/dev/net/tun"
+#else  /* linux */
+# define DEVTAP "/dev/tap0"
+#endif /* linux */
+
+/****************************************************************************
+ * Private Definitions
+ ****************************************************************************/
+
+#define TAPDEV_DEBUG    1
+
+#define UIP_DRIPADDR0   192
+#define UIP_DRIPADDR1   168
+#define UIP_DRIPADDR2   0
+#define UIP_DRIPADDR3   1
+
+/****************************************************************************
+ * Private Types
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Function Prototypes
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+#ifdef TAPDEV_DEBUG
+static int drop = 0;
+#endif
+static int fd;
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+unsigned long up_getwalltime( void )
+{
+  struct timeval tm;
+  (void)gettimeofday(&tm, NULL);
+  return tm.tv_sec*1000 + tm.tv_usec/1000;
+}
+
+void tapdev_init(void)
+{
+  char buf[1024];
+
+  fd = open(DEVTAP, O_RDWR);
+  if(fd == -1)
+    {
+      printf("tapdev: tapdev_init: open");
+      return;
+    }
+
+#ifdef linux
+  {
+    struct ifreq ifr;
+    memset(&ifr, 0, sizeof(ifr));
+    ifr.ifr_flags = IFF_TAP|IFF_NO_PI;
+    if (ioctl(fd, TUNSETIFF, (void *) &ifr) < 0)
+      {
+        printf(buf);
+        return;
+      }
+  }
+#endif /* Linux */
+
+  snprintf(buf, sizeof(buf), "ifconfig tap0 inet %d.%d.%d.%d",
+	   UIP_DRIPADDR0, UIP_DRIPADDR1, UIP_DRIPADDR2, UIP_DRIPADDR3);
+  system(buf);
+}
+
+unsigned int tapdev_read(char *buf, unsigned int buflen)
+{
+  fd_set fdset;
+  struct timeval tv;
+  int ret;
+
+  tv.tv_sec = 0;
+  tv.tv_usec = 1000;
+
+  FD_ZERO(&fdset);
+  FD_SET(fd, &fdset);
+
+  ret = select(fd + 1, &fdset, NULL, NULL, &tv);
+  if(ret == 0)
+    {
+      return 0;
+    }
+
+  ret = read(fd, buf, buflen);
+  if(ret == -1)
+    {
+      printf("tap_dev: tapdev_read: read");
+    }
+
+#ifdef TAPDEV_DEBUG
+  printf("tap_dev: tapdev_read: read %d bytes\n", ret);
+  {
+    int i;
+    for(i = 0; i < 20; i++)
+      {
+        printf("%x ", buf[i]);
+      }
+    printf("\n");
+  }
+#endif
+
+  return ret;
+}
+
+void tapdev_send(char *buf, unsigned int buflen)
+{
+  int ret;
+#ifdef TAPDEV_DEBUG
+  printf("tapdev_send: sending %d bytes\n", buflen);
+
+  drop++;
+  if(drop % 8 == 7)
+    {
+      printf("Dropped a packet!\n");
+      return;
+    }
+#endif
+
+  ret = write(fd, buf, buflen);
+  if(ret == -1)
+    {
+      perror("tap_dev: tapdev_send: write");
+      exit(1);
+    }
+}
+
diff --git a/arch/sim/src/up_uipdriver.c b/arch/sim/src/up_uipdriver.c
index e68c4fccd9..883207ab4d 100644
--- a/arch/sim/src/up_uipdriver.c
+++ b/arch/sim/src/up_uipdriver.c
@@ -44,35 +44,11 @@
 
 #include <nuttx/config.h>
 #include <sys/types.h>
-#include <sys/ioctl.h>
-#include <sys/socket.h>
-#include <sys/time.h>
-#include <sys/uio.h>
-#include <sys/socket.h>
-
-#include <stdlib.h>
-#include <stdio.h>
-#include <unistd.h>
-#include <string.h>
-#include <fcntl.h>
-#include <string.h>
-#include <time.h>
-#include <errno.h>
-#include <debug.h>
 
 #include <net/uip/uip.h>
 #include <net/uip/uip-arch.h>
 #include <net/uip/uip-arp.h>
 
-#ifdef linux
-# include <sys/ioctl.h>
-# include <linux/if.h>
-# include <linux/if_tun.h>
-# define DEVTAP "/dev/net/tun"
-#else  /* linux */
-# define DEVTAP "/dev/tap0"
-#endif /* linux */
-
 #include "up_internal.h"
 
 /****************************************************************************
@@ -81,11 +57,6 @@
 
 #define BUF ((struct uip_eth_hdr *)&uip_buf[0])
 
-#define UIP_DRIPADDR0   192
-#define UIP_DRIPADDR1   168
-#define UIP_DRIPADDR2   0
-#define UIP_DRIPADDR3   1
-
 /****************************************************************************
  * Private Types
  ****************************************************************************/
@@ -104,10 +75,6 @@ struct timer
  * Private Data
  ****************************************************************************/
 
-#ifdef CONFIG_DEBUG
-static int drop = 0;
-#endif
-static int fd;
 static struct timer periodic_timer;
 static struct timer arp_timer;
 
@@ -115,22 +82,15 @@ static struct timer arp_timer;
  * Private Functions
  ****************************************************************************/
 
-static uint32 gettime( void )
-{
-  struct timespec tm;
-  (void)clock_gettime(CLOCK_REALTIME, &tm);
-  return tm.tv_sec*1000 + tm.tv_nsec/1000000;
-}
-
 static void timer_set( struct timer *t, unsigned int interval )
 {
   t->interval = interval;
-  t->start    = gettime();
+  t->start    = up_getwalltime();
 }
 
 static boolean timer_expired( struct timer *t )
 {
-  return (gettime() - t->start) >= t->interval;
+  return (up_getwalltime() - t->start) >= t->interval;
 }
 
 void timer_reset(struct timer *t)
@@ -138,97 +98,6 @@ void timer_reset(struct timer *t)
   t->start += t->interval;
 }
 
-static void tapdev_init(void)
-{
-  char buf[1024];
-
-  fd = open(DEVTAP, O_RDWR);
-  if(fd == -1)
-    {
-      lib_rawprintf("tapdev: tapdev_init: open");
-      return;
-    }
-
-#ifdef linux
-  {
-    struct ifreq ifr;
-    memset(&ifr, 0, sizeof(ifr));
-    ifr.ifr_flags = IFF_TAP|IFF_NO_PI;
-    if (ioctl(fd, TUNSETIFF, (void *) &ifr) < 0)
-      {
-        lib_rawprintf(buf);
-        return;
-      }
-  }
-#endif /* Linux */
-
-  snprintf(buf, sizeof(buf), "ifconfig tap0 inet %d.%d.%d.%d",
-	   UIP_DRIPADDR0, UIP_DRIPADDR1, UIP_DRIPADDR2, UIP_DRIPADDR3);
-  system(buf);
-}
-
-static unsigned int tapdev_read(void)
-{
-  fd_set fdset;
-  struct timeval tv;
-  int ret;
-
-  tv.tv_sec = 0;
-  tv.tv_usec = 1000;
-
-  FD_ZERO(&fdset);
-  FD_SET(fd, &fdset);
-
-  ret = select(fd + 1, &fdset, NULL, NULL, &tv);
-  if(ret == 0)
-    {
-      return 0;
-    }
-  ret = read(fd, uip_buf, UIP_BUFSIZE);
-  if(ret == -1)
-    {
-      lib_rawprintf("tap_dev: tapdev_read: read");
-    }
-
-  dbg("tap_dev: tapdev_read: read %d bytes\n", ret);
-  {
-    int i;
-    for(i = 0; i < 20; i++)
-      {
-        vdbg("%x ", uip_buf[i]);
-      }
-    vdbg("\n");
-  }
-
-#ifdef CONFIG_DEBUG
-  check_checksum(uip_buf, ret);
-#endif
-  return ret;
-}
-
-static void tapdev_send(void)
-{
-  int ret;
-#ifdef CONFIG_DEBUG
-  dbg("tapdev_send: sending %d bytes\n", uip_len);
-  check_checksum(uip_buf, uip_len);
-
-  drop++;
-  if(drop % 8 == 7)
-    {
-      dbg("Dropped a packet!\n");
-      return;
-    }
-#endif
-
-  ret = write(fd, uip_buf, uip_len);
-  if(ret == -1)
-    {
-      perror("tap_dev: tapdev_send: writev");
-      exit(1);
-    }
-}
-
 /****************************************************************************
  * Public Functions
  ****************************************************************************/
@@ -237,7 +106,7 @@ void uipdriver_loop(void)
 {
   int i;
 
-  uip_len = tapdev_read();
+  uip_len = tapdev_read(uip_buf, UIP_BUFSIZE);
   if (uip_len > 0)
     {
       if (BUF->type == htons(UIP_ETHTYPE_IP))
@@ -253,7 +122,7 @@ void uipdriver_loop(void)
           if (uip_len > 0)
             {
               uip_arp_out();
-              tapdev_send();
+              tapdev_send(uip_buf, uip_len);
             }
         }
       else if (BUF->type == htons(UIP_ETHTYPE_ARP))
@@ -267,7 +136,7 @@ void uipdriver_loop(void)
 
           if (uip_len > 0)
             {
-              tapdev_send();
+              tapdev_send(uip_buf, uip_len);
             }
         }
     }
@@ -286,7 +155,7 @@ void uipdriver_loop(void)
           if (uip_len > 0)
             {
               uip_arp_out();
-              tapdev_send();
+              tapdev_send(uip_buf, uip_len);
             }
         }
 
@@ -303,7 +172,7 @@ void uipdriver_loop(void)
           if (uip_len > 0)
             {
               uip_arp_out();
-              tapdev_send();
+              tapdev_send(uip_buf, uip_len);
             }
         }
 #endif /* UIP_UDP */
@@ -320,8 +189,8 @@ void uipdriver_loop(void)
 
 int uipdriver_init(void)
 {
-  timer_set(&periodic_timer, CLK_TCK / 2);
-  timer_set(&arp_timer, CLK_TCK * 10);
+  timer_set(&periodic_timer, 500);
+  timer_set(&arp_timer, 10000 );
 
   tapdev_init();
   uip_init();