diff --git a/ubb-la/gui.c b/ubb-la/gui.c
index d8d538e..f73c234 100644
--- a/ubb-la/gui.c
+++ b/ubb-la/gui.c
@@ -41,6 +41,7 @@
 #define	LEVEL_RGBA	0xffff00ff	/* constant level or single change */
 #define	BOUNCE_RGBA	0xff8080ff	/* bouncing signal */
 #define	LABEL_RGBA	0xffffffff	/* channel label */
+#define	DIV_RGBA	0x808080ff	/* divisions */
 
 #define	XCENTER		((XRES+CH_XOFF)/2)
 
@@ -54,6 +55,9 @@
 #define	CH_SKIP		16
 #define	CH_HEIGHT	8
 
+#define	DIV_X		32
+#define	DIV_Y		6
+
 #define	MAX_ZOOM	3
 
 #define	FREQ_X		0
@@ -342,6 +346,20 @@ static void show_freq(double freq)
 }
 
 
+/* ----- Show a divisions -------------------------------------------------- */
+
+
+static void show_divisions(void)
+{
+	int n = (XRES-CH_XOFF)/2/DIV_X;
+	int i;
+
+	for (i = -n; i <= n; i++)
+		vlineColor(surf, XCENTER+i*DIV_X,
+		    ch_y(0, 1)-DIV_Y, ch_y(3, 0)+DIV_Y, DIV_RGBA);
+}
+
+
 /* ----- Main event loop --------------------------------------------------- */
 
 
@@ -366,6 +384,7 @@ void gui(const uint8_t *buf, int skip, int nibbles, double freq)
 		clear();
 		for (i = 0; i != 4; i++)
 			textf(0, ch_y(i, 1), LABEL_RGBA, "CH%d", i);
+		show_divisions();
 		show_buffer(buf, skip, nibbles, CH_XOFF, XRES, zoom, pos);
 		show_freq(freq);
 		update();