diff --git a/jtag/ChangeLog b/jtag/ChangeLog
index a8aa9a04..12b26d18 100644
--- a/jtag/ChangeLog
+++ b/jtag/ChangeLog
@@ -8,6 +8,9 @@
 
 2008-02-16  Kolja Waschk <kawk>
 
+    * src/cmd/scan.c, src/cmd/Makefile.am, src/cmd/cmd.c: Implemented basic
+        boundary "scan" command to detect changes on input pins; tested with
+        an (completely erased) Actel ProASIC3 A3P125
     * src/svf/svf.c: Small fix for computation of run_count from min_time
     * doc/UrJTAG.txt: Updated doc about building with FTD2XX in Cygwin
     * src/tap/cable.c, include/cable.h, src/tap/cable/*.c (all drivers):
diff --git a/jtag/src/cmd/Makefile.am b/jtag/src/cmd/Makefile.am
index 17c2a9b7..dbefd5fc 100644
--- a/jtag/src/cmd/Makefile.am
+++ b/jtag/src/cmd/Makefile.am
@@ -34,6 +34,7 @@ libcmd_a_SOURCES = \
 	detectflash.c \
 	help.c \
 	quit.c \
+	scan.c \
 	signal.c \
 	salias.c \
 	bit.c \
diff --git a/jtag/src/cmd/cmd.c b/jtag/src/cmd/cmd.c
index 29dfecbc..983adf92 100644
--- a/jtag/src/cmd/cmd.c
+++ b/jtag/src/cmd/cmd.c
@@ -39,6 +39,7 @@ extern cmd_t cmd_reset;
 extern cmd_t cmd_discovery;
 extern cmd_t cmd_detect;
 extern cmd_t cmd_signal;
+extern cmd_t cmd_scan;
 extern const cmd_t cmd_salias;
 extern cmd_t cmd_bit;
 extern cmd_t cmd_register;
@@ -80,6 +81,7 @@ const cmd_t *cmds[] = {
 	&cmd_discovery,
 	&cmd_detect,
 	&cmd_signal,
+	&cmd_scan,
 	&cmd_salias,
 	&cmd_bit,
 	&cmd_register,
diff --git a/jtag/src/cmd/scan.c b/jtag/src/cmd/scan.c
new file mode 100644
index 00000000..432c93d1
--- /dev/null
+++ b/jtag/src/cmd/scan.c
@@ -0,0 +1,138 @@
+/*
+ * $Id: scan.c 733 2007-11-07 22:21:33Z arniml $
+ *
+ * Copyright (C) 2003 ETC s.r.o.
+ *
+ * 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., 59 Temple Place - Suite 330, Boston, MA
+ * 02111-1307, USA.
+ *
+ * Written by Marcel Telka <marcel@telka.sk>, 2003.
+ *
+ */
+
+#include "sysdep.h"
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "jtag.h"
+
+#include "cmd.h"
+
+static int
+cmd_scan_run( char *params[] )
+{
+	part_t *part;
+    data_register *bsr;
+	tap_register *obsr;
+	int i;
+
+	if ((i = cmd_params( params )) < 1)
+		return -1;
+
+	if (!cmd_test_cable())
+		return 1;
+
+	if (!chain->parts) {
+		printf( _("Run \"detect\" first.\n") );
+		return 1;
+	}
+
+	if (chain->active_part >= chain->parts->len) {
+		printf( _("%s: no active part\n"), "scan" );
+		return 1;
+	}
+
+	part = chain->parts->parts[chain->active_part];
+
+	/* search for Boundary Scan Register */
+	bsr = part_find_data_register( part, "BSR" );
+	if (!bsr) {
+		printf( _("%s(%s:%d) Boundary Scan Register (BSR) not found\n"), __FUNCTION__, __FILE__, __LINE__ );
+		return 1;
+	}
+
+	if(part_find_instruction( part, "SAMPLE"))
+	{
+		part_set_instruction( part, "SAMPLE");
+	}
+	else if(part_find_instruction( part, "SAMPLE/PRELOAD"))
+	{
+		part_set_instruction( part, "SAMPLE/PRELOAD");
+	}
+	else
+	{
+		printf( _("%s(%s:%d) Part can't SAMPLE\n"), __FUNCTION__, __FILE__, __LINE__ );
+		return 1;
+	};
+
+	chain_shift_instructions( chain );
+
+	obsr = register_alloc( bsr->out->len );
+
+	if(!obsr)
+	{
+		printf( _("Out of memory\n") );
+		return 1;
+	}
+
+	{
+		signal_t *s;
+
+		register_init( obsr, register_get_string( bsr->out )); // copy
+
+		chain_shift_data_registers( chain, 1 );
+
+		for(s=part->signals; s; s=s->next)
+		{
+			if(s->input != NULL)
+			{
+				int old = obsr->data[s->input->bit];
+				int new = bsr->out->data[s->input->bit];
+				if( old != new ) 
+				{
+					salias_t *a;
+					printf("%s", s->name);
+					for(a = part->saliases; a; a=a->next)
+					{
+						if(a->signal == s) printf(",%s", a->name);
+					}
+					printf( _(": %d > %d\n"), old, new);
+				}
+			}
+		}
+	}
+
+	register_free( obsr );
+
+	return 1;
+}
+
+static void
+cmd_scan_help( void )
+{
+	printf( _(
+		"Usage: %s [SIGNAL]* \n"
+		"Read BSR and show changes since last scan.\n"
+	), "scan" );
+}
+
+cmd_t cmd_scan = {
+	"scan",
+	N_("read BSR and show changes since last scan"),
+	cmd_scan_help,
+	cmd_scan_run
+};