diff --git a/testprogram.js b/testprogram.js
index dff8bfa..0e01f3a 100644
--- a/testprogram.js
+++ b/testprogram.js
@@ -8,8 +8,21 @@
 //
 testprogramAddress=0x0000;
 
+// demonstrate write hook
+writeTriggers[0x000c]="consolebox.innerHTML = consolebox.innerHTML + String.fromCharCode(d);";
+
 testprogram = [
-	0xa9, 0x00, 0x20, 0x10, 0x00, 0x4c, 0x02, 0x00,
-	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
-	0xe8, 0x88, 0xe6, 0x40, 0x38, 0x69, 0x02, 0x60
+	0xa9, 0x00,              // LDA #$00
+	0x20, 0x10, 0x00,        // JSR $0010
+	0x4c, 0x02, 0x00,        // JMP $0002
+
+	0x00, 0x00, 0x00, 0x00,
+	0x40, 0x00, 0x00, 0x00,
+
+	0xe8,                    // INX
+	0x88,                    // DEY
+	0xe6, 0x0c,              // INC $0C
+	0x38,                    // SEC
+	0x69, 0x02,              // ADC #$02
+	0x60                     // RTS
 ];