diff --git a/include/jtag/part.h b/include/jtag/part.h
index dda8917e..daac564e 100644
--- a/include/jtag/part.h
+++ b/include/jtag/part.h
@@ -42,14 +42,11 @@ struct part {
 	data_register *data_registers;
 	int boundary_length;
 	bsbit **bsbits;
-	tap_register *idr;
-	tap_register *bsr;
-	tap_register *prev_bsr;
 };
 
 part *part_alloc( void );
 void part_free( part *p );
-part *read_part( FILE *f, const tap_register *idr );
+part *read_part( FILE *f, tap_register *idr );
 instruction *part_find_instruction( part *p, const char *iname );
 data_register *part_find_data_register( part *p, const char *drname );
 void part_set_signal( part *p, const char *pname, int out, int val );
diff --git a/jtag/src/part/parse.c b/jtag/src/part/parse.c
index f2064d60..542d9d95 100644
--- a/jtag/src/part/parse.c
+++ b/jtag/src/part/parse.c
@@ -39,7 +39,7 @@ get_token( char *buf )
 }
 
 part *
-read_part( FILE *f, const tap_register *idr )
+read_part( FILE *f, tap_register *idr )
 {
 	int line = 0;
 	part *part;
@@ -53,8 +53,6 @@ read_part( FILE *f, const tap_register *idr )
 		return NULL;
 	}
 
-	part->idr = register_duplicate( idr );
-
 	for (;;) {
 		char *t;
 		char buf[1024];
@@ -122,6 +120,7 @@ read_part( FILE *f, const tap_register *idr )
 			dr->next = part->data_registers;
 			part->data_registers = dr;
 
+			/* Boundary Scan Register */
 			if (strcmp( dr->name, "BSR" ) == 0) {
 				int i;
 
@@ -135,6 +134,10 @@ read_part( FILE *f, const tap_register *idr )
 					part->bsbits[i] = NULL;
 			}
 
+			/* Device Identification Register */
+			if (strcmp( dr->name, "DIR" ) == 0)
+				register_init( dr->value, register_get_string( idr ) );
+
 			continue;
 		}
 
diff --git a/jtag/src/part/part.c b/jtag/src/part/part.c
index 6cd2bdfe..f25465a4 100644
--- a/jtag/src/part/part.c
+++ b/jtag/src/part/part.c
@@ -44,9 +44,6 @@ part_alloc( void )
 	p->data_registers = NULL;
 	p->boundary_length = 0;
 	p->bsbits = NULL;
-	p->idr = NULL;
-	p->bsr = NULL;
-	p->prev_bsr = NULL;
 
 	return p;
 }
@@ -73,6 +70,7 @@ part_free( part *p )
 		instruction_free( i );
 	}
 
+	/* data registers */
 	while (p->data_registers) {
 		data_register *dr = p->data_registers;
 		p->data_registers = dr->next;
@@ -84,13 +82,6 @@ part_free( part *p )
 		bsbit_free( p->bsbits[i] );
 	free( p->bsbits );
 
-	/* idr */
-	register_free( p->idr );
-
-	/* bsr */
-	register_free( p->bsr );
-	register_free( p->prev_bsr );
-
 	free( p );
 }
 
@@ -133,8 +124,17 @@ part_find_data_register( part *p, const char *drname )
 void
 part_set_signal( part *p, const char *pname, int out, int val )
 {
+	signal *s;
+
+	/* search for Boundary Scan Register */
+	data_register *bsr = part_find_data_register( p, "BSR" );
+	if (!bsr) {
+		printf( "%s(%s:%d) Boundary Scan Register (BSR) not found\n", __FUNCTION__, __FILE__, __LINE__ );
+		return;
+	}
+
 	/* search signal */
-	signal *s = p->signals;
+	s = p->signals;
 	while (s) {
 		if (strcmp( pname, s->name ) == 0)
 			break;
@@ -153,26 +153,35 @@ part_set_signal( part *p, const char *pname, int out, int val )
 			printf( "signal %s cannot be set as output\n", pname );
 			return;
 		}
-		p->bsr->data[s->output->bit] = val & 1;
+		bsr->value->data[s->output->bit] = val & 1;
 
 		control = p->bsbits[s->output->bit]->control;
 		if (control >= 0)
-			p->bsr->data[control] = p->bsbits[s->output->bit]->control_value ^ 1;
+			bsr->value->data[control] = p->bsbits[s->output->bit]->control_value ^ 1;
 	} else {
 		if (!s->input) {
 			printf( "signal %s cannot be set as input\n", pname );
 			return;
 		}
 		if (s->output)
-			p->bsr->data[s->output->control] = p->bsbits[s->output->control]->control_value;
+			bsr->value->data[s->output->control] = p->bsbits[s->output->control]->control_value;
 	}
 }
 
 int
 part_get_signal( part *p, const char *pname )
 {
+	signal *s;
+
+	/* search for Boundary Scan Register */
+	data_register *bsr = part_find_data_register( p, "BSR" );
+	if (!bsr) {
+		printf( "%s(%s:%d) Boundary Scan Register (BSR) not found\n", __FUNCTION__, __FILE__, __LINE__ );
+		return -1;
+	}
+
 	/* search signal */
-	signal *s = p->signals;
+	s = p->signals;
 	while (s) {
 		if (strcmp( pname, s->name ) == 0)
 			break;
@@ -189,7 +198,7 @@ part_get_signal( part *p, const char *pname )
 		return -1;
 	}
 
-	return p->prev_bsr->data[s->input->bit];
+	return bsr->value->data[s->input->bit];
 }
 
 /* parts */