diff --git a/lpc111x-isp/lpc111x.c b/lpc111x-isp/lpc111x.c
index ff323dc..080ed64 100644
--- a/lpc111x-isp/lpc111x.c
+++ b/lpc111x-isp/lpc111x.c
@@ -17,6 +17,7 @@
 #include <stdio.h>
 #include <unistd.h>
 #include <string.h>
+#include <strings.h>	/* for strcasecmp, strncasecmp */
 #include <alloca.h>
 #include <assert.h>
 #include <sys/types.h>
@@ -58,7 +59,7 @@ static struct pin {
 	const char *name;
 	const char *alt_name;
 	uint32_t pin;
-} pin[] = {
+} pins[] = {
 	[pin_rxd]	= { "RXD",	"P1_6",	UBB_DAT2 },
 	[pin_txd]	= { "TXD",	"P1_7",	UBB_DAT3 },
 	[pin_nisp]	= { "nISP",	"P0_1",	UBB_DAT1 },
@@ -66,6 +67,19 @@ static struct pin {
 	[pin_end]	= { NULL }
 };
 
+static const struct signal {
+	const char *name;
+	uint32_t pin;
+} signals[] = {
+	{ "CMD",	UBB_CMD },
+	{ "CLK",	UBB_CLK },
+	{ "DAT0",	UBB_DAT0 },
+	{ "DAT1",	UBB_DAT1 },
+	{ "DAT2",	UBB_DAT2 },
+	{ "DAT3",	UBB_DAT3 },
+	{ NULL }
+};
+
 static int verbose = 0;
 static int quiet = 0;
 
@@ -223,9 +237,9 @@ static int autobaud(void)
 	const char *res;
 
 	for (i = 0; i != AUTOBAUD_TRIES; i++) {
-		CLR(pin[pin_nreset].pin);
+		CLR(pins[pin_nreset].pin);
 		usleep(10);	/* DS Table 9 pg 29 says min 50 ns */
-		SET(pin[pin_nreset].pin);
+		SET(pins[pin_nreset].pin);
 
 		usleep(5*1000);	/* UM 26.3.1 pg 408 says max 3 ms */
 
@@ -555,13 +569,13 @@ static void start_isp(int power)
 
 	usleep(100*1000);
 
-	SET(pin[pin_nreset].pin);
-	OUT(pin[pin_nreset].pin);
+	SET(pins[pin_nreset].pin);
+	OUT(pins[pin_nreset].pin);
 
-	CLR(pin[pin_nisp].pin);
-	OUT(pin[pin_nisp].pin);
+	CLR(pins[pin_nisp].pin);
+	OUT(pins[pin_nisp].pin);
 
-	if (swuart_open(pin[pin_rxd].pin, pin[pin_txd].pin, BPS) < 0) {
+	if (swuart_open(pins[pin_rxd].pin, pins[pin_txd].pin, BPS) < 0) {
 		perror("swuart_open");
 		exit(1);
 	}
@@ -592,16 +606,16 @@ static void run_target(int power)
 	if (power)
 		ubb_power(1);
 
-	SET(pin[pin_nreset].pin);
-	OUT(pin[pin_nreset].pin);
+	SET(pins[pin_nreset].pin);
+	OUT(pins[pin_nreset].pin);
 
-	IN(pin[pin_nisp].pin);
+	IN(pins[pin_nisp].pin);
 
-	CLR(pin[pin_nreset].pin);
+	CLR(pins[pin_nreset].pin);
 	usleep(10);	/* DS Table 9 pg 29 says min 50 ns */
-	SET(pin[pin_nreset].pin);
+	SET(pins[pin_nreset].pin);
 
-	ubb_close(UBB_nPWR | pin[pin_nreset].pin | pin[pin_nisp].pin);
+	ubb_close(UBB_nPWR | pins[pin_nreset].pin | pins[pin_nisp].pin);
 }
 
 
@@ -610,18 +624,67 @@ static void run_target(int power)
 
 static void usage(const char *name)
 {
+	const struct signal *signal;
+	int i;
+
 	fprintf(stderr,
-"usage: %s [-n] [-q] [-v ...] [file.bin]\n"
-"       %s [-n] -r\n\n"
-"  -n  don't power the device\n"
-"  -q  suppress basic progress messages\n"
-"  -r  reset the target and let it run\n"
-"  -v  increase verbosity level\n"
+"usage: %s [-P function=signal ...] [-n] [-q] [-v ...] [file.bin]\n"
+"       %s [-P function=signal ...] [-n] -r\n\n"
+"  -n                  don't power the device\n"
+"  -q                  suppress basic progress messages\n"
+"  -P function=signal  assign a 8:10 interface signal to a function "
+  "(see below)\n"
+"  -r                  reset the target and let it run\n"
+"  -v                  increase verbosity level\n\n"
+"Functions: RXD (P1_6), TXD (P1_7), nISP (P0_1), nRESET (P0_0)\n"
+"Signals: CMD, CLK, DAT0, DAT1, DAT2, DAT3\n"
     , name, name);
+
+	fprintf(stderr, "Default mapping:");
+	for (i = 0; i != pin_end; i++) {
+		for (signal = signals; signal->pin != pins[i].pin; signal++);
+		fprintf(stderr, " -P %s=%s", pins[i].name, signal->name);
+	}
+	fprintf(stderr, "\n");
 	exit(1);
 }
 
 
+static void assign_pin(const char *name, const char *s)
+{
+	const char *eq;
+	struct pin *pin;
+	const struct signal *signal;
+
+	eq = strchr(s, '=');
+	if (!eq)
+		usage(name);
+
+	for (pin = pins; pin->name; pin++) {
+		if (strlen(pin->name) == eq-s &&
+		    !strncasecmp(pin->name, s, eq-s))
+			break;
+		if (strlen(pin->alt_name) == eq-s &&
+		    !strncasecmp(pin->alt_name, s, eq-s))
+			break;
+	}
+	if (!pin->name) {
+		fprintf(stderr, "unknown function \"%.*s\"\n", eq-s, s);
+		exit(1);
+	}
+
+	for (signal = signals; signal->name; signal++)
+		if (!strcasecmp(signal->name, eq+1))
+			break;
+	if (!signal->name) {
+		fprintf(stderr, "unknown signal \"%s\"\n", eq+1);
+		exit(1);
+	}
+
+	pin->pin = signal->pin;
+}
+
+
 int main(int argc, char **argv)
 {
 	FILE *file = NULL;
@@ -629,11 +692,14 @@ int main(int argc, char **argv)
 	int run = 0;
 	int c;
 
-	while ((c = getopt(argc, argv, "nqrv")) != EOF)
+	while ((c = getopt(argc, argv, "nP:qrv")) != EOF)
 		switch (c) {
 		case 'n':
 			power = 0;
 			break;
+		case 'P':
+			assign_pin(*argv, optarg);
+			break;
 		case 'q':
 			quiet = 1;
 			break;