diff --git a/Makefile b/Makefile
index f5b9d5f..9dbbbac 100644
--- a/Makefile
+++ b/Makefile
@@ -64,7 +64,7 @@ mspdebug: main.o fet.o rf2500.o dis.o uif.o olimex.o ihex.o elf32.o stab.o \
 	  reader.o vector.o output_util.o expr.o fet_error.o binfile.o \
 	  fet_db.o usbutil.o titext.o srec.o device.o coff.o opdb.o output.o \
 	  cmddb.o stdcmd.o prog.o flash_bsl.o list.o simio.o simio_tracer.o \
-	  simio_timer.o simio_wdt.o
+	  simio_timer.o simio_wdt.o simio_hwmult.o
 	$(CC) $(LDFLAGS) $(PORTS_LDFLAGS) -o $@ $^ -lusb $(READLINE_LIBS)
 
 .c.o:
diff --git a/mspdebug.man b/mspdebug.man
index 45f64f1..69d1410 100644
--- a/mspdebug.man
+++ b/mspdebug.man
@@ -435,6 +435,9 @@ device classes in detail.
 
 In the list below, each device class is listed, followed by its constructor
 arguments.
+.IP "\fBhwmult\fR"
+This peripheral simulates the hardware multiplier. It has no constructor or
+configuration parameters, and does not provide any extended information.
 .IP "\fBtimer\fR [\fIsize\fR]"
 This peripheral simulators Timer_A modules, and can be used to simulate
 Timer_B modules, provided that the extended features aren't required.
diff --git a/simio.c b/simio.c
index f2fc750..392cf58 100644
--- a/simio.c
+++ b/simio.c
@@ -27,11 +27,13 @@
 #include "simio_tracer.h"
 #include "simio_timer.h"
 #include "simio_wdt.h"
+#include "simio_hwmult.h"
 
 static const struct simio_class *const class_db[] = {
 	&simio_tracer,
 	&simio_timer,
-	&simio_wdt
+	&simio_wdt,
+	&simio_hwmult
 };
 
 /* Simulator data. We keep a list of devices on the bus, and the special
@@ -157,7 +159,10 @@ static int cmd_devices(char **arg_text)
 
 	for (n = device_list.next; n != &device_list; n = n->next) {
 		struct simio_device *dev = (struct simio_device *)n;
-		int irq = dev->type->check_interrupt(dev);
+		int irq = -1;
+
+		if (dev->type->check_interrupt)
+			irq = dev->type->check_interrupt(dev);
 
 		printc("    %-10s (type %s", dev->name, dev->type->name);
 		if (irq < 0)
@@ -228,6 +233,12 @@ static int cmd_config(char **arg_text)
 		return -1;
 	}
 
+	if (!dev->type->config) {
+		printc_err("simio config: no configuration parameters are "
+			   "defined for this device\n");
+		return -1;
+	}
+
 	return dev->type->config(dev, param, arg_text);
 }
 
@@ -247,6 +258,11 @@ static int cmd_info(char **arg_text)
 		return -1;
 	}
 
+	if (!dev->type->info) {
+		printc_err("simio config: no information available\n");
+		return -1;
+	}
+
 	return dev->type->info(dev);
 }
 
diff --git a/simio_hwmult.c b/simio_hwmult.c
new file mode 100644
index 0000000..05cd8a9
--- /dev/null
+++ b/simio_hwmult.c
@@ -0,0 +1,163 @@
+/* MSPDebug - debugging tool for MSP430 MCUs
+ * Copyright (C) 2009, 2010 Daniel Beer
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+
+#include <stdlib.h>
+#include <string.h>
+
+#include "simio_device.h"
+#include "simio_hwmult.h"
+#include "output.h"
+#include "expr.h"
+
+/* Multiplier register addresses - taken from mspgcc */
+#define MPY                0x0130  /* Multiply Unsigned/Operand 1 */
+#define MPYS               0x0132  /* Multiply Signed/Operand 1 */
+#define MAC                0x0134  /* Multiply Unsigned and Accumulate/Operand 1 */
+#define MACS               0x0136  /* Multiply Signed and Accumulate/Operand 1 */
+#define OP2                0x0138  /* Operand 2 */
+#define RESLO              0x013A  /* Result Low Word */
+#define RESHI              0x013C  /* Result High Word */
+#define SUMEXT             0x013E  /* Sum Extend */
+
+struct hwmult {
+	struct simio_device		base;
+
+	int				mode;
+
+	uint16_t			op1;
+	uint16_t			op2;
+	uint32_t			result;
+	uint16_t			sumext;
+};
+
+struct simio_device *hwmult_create(char **arg_text)
+{
+	struct hwmult *h = malloc(sizeof(*h));
+
+	if (!h) {
+		pr_error("hwmult: can't allocate memory");
+		return NULL;
+	}
+
+	memset(h, 0, sizeof(*h));
+	h->base.type = &simio_hwmult;
+
+	return (struct simio_device *)h;
+}
+
+static void hwmult_destroy(struct simio_device *dev)
+{
+	free(dev);
+}
+
+static void do_multiply(struct hwmult *h)
+{
+	uint32_t im;
+
+	/* Multiply */
+	if (h->mode & 2)
+		im = (int16_t)h->op1 * (int16_t)h->op2;
+	else
+		im = h->op1 * h->op2;
+
+	/* Accumulate or store */
+	if (h->mode & 4)
+		h->result += im;
+	else
+		h->result = im;
+
+	/* Set SUMEXT */
+	if (h->mode & 2)
+		h->sumext = (h->result & 0x80000000) ? 0xffff : 0;
+	else if (h->mode == MPY)
+		h->sumext = (h->result < im) ? 1 : 0;
+	else
+		h->sumext = 0;
+}
+
+static int hwmult_write(struct simio_device *dev, address_t addr, uint16_t data)
+{
+	struct hwmult *h = (struct hwmult *)dev;
+
+	switch (addr) {
+	case RESHI:
+		h->result = (h->result & 0xffff) | ((uint32_t)data << 16);
+		return 0;
+
+	case RESLO:
+		h->result = (h->result & 0xffff0000) | data;
+		return 0;
+
+	case OP2:
+		h->op2 = data;
+		do_multiply(h);
+		return 0;
+
+	case MPY:
+	case MPYS:
+	case MAC:
+	case MACS:
+		h->op1 = data;
+		h->mode = addr;
+		return 0;
+	}
+
+	return 1;
+}
+
+static int hwmult_read(struct simio_device *dev, address_t addr, uint16_t *data)
+{
+	struct hwmult *h = (struct hwmult *)dev;
+
+	switch (addr) {
+	case MPY:
+	case MPYS:
+	case MAC:
+	case MACS:
+		*data = h->op1;
+		return 0;
+
+	case OP2:
+		*data = h->op2;
+		return 0;
+
+	case RESLO:
+		*data = h->result & 0xffff;
+		return 0;
+
+	case RESHI:
+		*data = h->result >> 16;
+		return 0;
+
+	case SUMEXT:
+		*data = h->sumext;
+		return 0;
+	}
+
+	return 1;
+}
+
+const struct simio_class simio_hwmult = {
+	.name = "hwmult",
+	.help =
+"This module simulates the hardware multiplier.\n",
+	.create			= hwmult_create,
+	.destroy		= hwmult_destroy,
+	.write			= hwmult_write,
+	.read			= hwmult_read
+};
diff --git a/simio_hwmult.h b/simio_hwmult.h
new file mode 100644
index 0000000..f15b8f0
--- /dev/null
+++ b/simio_hwmult.h
@@ -0,0 +1,24 @@
+/* MSPDebug - debugging tool for MSP430 MCUs
+ * Copyright (C) 2009, 2010 Daniel Beer
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+
+#ifndef SIMIO_HWMULT_H_
+#define SIMIO_HWMULT_H_
+
+extern const struct simio_class simio_hwmult;
+
+#endif