diff --git a/cngt/cngt.c b/cngt/cngt.c
index ccbe42e..f67a341 100644
--- a/cngt/cngt.c
+++ b/cngt/cngt.c
@@ -20,12 +20,14 @@
 
 #define	MAX_POS	10
 #define	STEP	5	/* xy movement step, 5 mm */
+#define	STEP_Z	1	/* z movement step, 1 mm */
 
 
 static double pos_x[MAX_POS];
 static double pos_y[MAX_POS];
 static double z0, height;
 static double cx, cy, cz;
+static int positioning = 0;
 
 
 #define UNITS(mm)	((mm)*40.0)
@@ -58,10 +60,20 @@ static int do_key(char c)
 
 	switch (c) {
 	case 'u':
-		up();
+		if (positioning) {
+			cz += STEP_Z;
+			move();
+		} else {
+			up();
+		}
 		return 0;
 	case 'd':
-		down();
+		if (positioning) {
+			cz -= STEP_Z;
+			move();
+		} else {
+			down();
+		}
 		return 0;
 	case 'q':
 		return 1;
@@ -71,7 +83,8 @@ static int do_key(char c)
 
 	/* Only x/y positioning */
 
-	up();
+	if (!positioning)
+		up();
 
 	switch (c) {
 	case 'h':
@@ -87,6 +100,8 @@ static int do_key(char c)
 		cx += STEP;
 		break;
 	default:
+		if (positioning)
+			return 0;
 		if (c < '0' || c > '9')
 			return 0;
 		cx = pos_x[c-'0'];
@@ -141,7 +156,10 @@ static void gp_minmax(const char *name,
 
 static void usage(const char *name)
 {
-	fprintf(stderr, "usage: %s z0 height (file | x y ...)\n", name);
+	fprintf(stderr,
+"usage: %s z0 height [file | x y ...]\n"
+"       %s z0\n"
+    , name, name);
 	exit(1);
 }
 
@@ -152,27 +170,32 @@ int main(int argc, char **argv)
 	int i;
 	char c;
 
-	if (argc < 4)
+	if (argc < 2)
 		usage(*argv);
 
 	z0 = atof(argv[1]);
-	height = atof(argv[2]);
 
-	if (argc & 1) {
-		for (i = 3; i != argc; i += 2) {
-			pos_x[(i-3)/2] = atof(argv[i]);
-			pos_y[(i-3)/2] = atof(argv[i+1]);
-		}
+	if (argc == 2) {
+		positioning = 1;
+		height = 0;
 	} else {
-		if (argc != 4)
-			usage(*argv);
-		gp_minmax(argv[3], &xa, &ya, &xb, &yb);
-		pos_x[1] = pos_x[4] = pos_x[7] = xa;
-		pos_x[2] = pos_x[5] = pos_x[8] = (xa+xb)/2;
-		pos_x[3] = pos_x[6] = pos_x[9] = xb;
-		pos_y[1] = pos_y[2] = pos_y[3] = ya;
-		pos_y[4] = pos_y[5] = pos_y[6] = (ya+yb)/2;
-		pos_y[7] = pos_y[8] = pos_y[9] = yb;
+		height = atof(argv[2]);
+		if (argc & 1) {
+			for (i = 3; i != argc; i += 2) {
+				pos_x[(i-3)/2] = atof(argv[i]);
+				pos_y[(i-3)/2] = atof(argv[i+1]);
+			}
+		} else {
+			if (argc != 4)
+				usage(*argv);
+			gp_minmax(argv[3], &xa, &ya, &xb, &yb);
+			pos_x[1] = pos_x[4] = pos_x[7] = xa;
+			pos_x[2] = pos_x[5] = pos_x[8] = (xa+xb)/2;
+			pos_x[3] = pos_x[6] = pos_x[9] = xb;
+			pos_y[1] = pos_y[2] = pos_y[3] = ya;
+			pos_y[4] = pos_y[5] = pos_y[6] = (ya+yb)/2;
+			pos_y[7] = pos_y[8] = pos_y[9] = yb;
+		}
 	}
 
 	serial_open("/dev/ttyUSB0");
@@ -183,9 +206,12 @@ int main(int argc, char **argv)
 	cz = z0+height;
 	move();
 
-	while ((c = getkey()))
+	while ((c = getkey())) {
 		if (do_key(c))
 			break;
+		if (positioning)
+			printf("%f %f %f\r\n", cx, cy, cz);
+	}
 	up();
 	serial_close();
 	return 0;