diff --git a/src/main/java/de/neemann/digital/draw/shapes/InputShape.java b/src/main/java/de/neemann/digital/draw/shapes/InputShape.java
index 374ef53a6..9b909f409 100644
--- a/src/main/java/de/neemann/digital/draw/shapes/InputShape.java
+++ b/src/main/java/de/neemann/digital/draw/shapes/InputShape.java
@@ -40,6 +40,7 @@ public class InputShape implements Shape {
     private IOState ioState;
     private SingleValueDialog dialog;
     private Value value;
+    private Value inValue;
     private final boolean isHighZ;
 
     /**
@@ -111,8 +112,11 @@ public class InputShape implements Shape {
 
     @Override
     public void readObservableValues() {
-        if (ioState != null)
+        if (ioState != null) {
             value = ioState.getOutput(0).getCopy();
+            if (ioState.inputCount() == 1)
+                inValue = ioState.getInput(0).getCopy();
+        }
     }
 
     @Override
@@ -124,17 +128,22 @@ public class InputShape implements Shape {
             graphic.drawText(textPos, textPos.add(1, 0), label, Orientation.RIGHTCENTER, Style.INOUT);
         } else {
             Style style = Style.NORMAL;
+            final Polygon box = new Polygon(true).add(-SIZE * 2 - 1, -SIZE).add(-1, -SIZE).add(-1, SIZE).add(-SIZE * 2 - 1, SIZE);
             if (value != null) {
                 style = Style.getWireStyle(value);
                 if (value.getBits() > 1) {
                     Vector textPos = new Vector(-1 - SIZE, -4 - SIZE);
                     graphic.drawText(textPos, textPos.add(1, 0), format.formatToView(value), Orientation.CENTERBOTTOM, Style.NORMAL);
+                } else {
+                    if (inValue != null && !inValue.isEqual(value))
+                        graphic.drawPolygon(box, Style.getWireStyle(inValue));
                 }
             }
 
+            graphic.drawPolygon(box, Style.NORMAL);
+
             Vector center = new Vector(-1 - SIZE, 0);
             graphic.drawCircle(center.sub(RAD), center.add(RAD), style);
-            graphic.drawPolygon(new Polygon(true).add(-SIZE * 2 - 1, -SIZE).add(-1, -SIZE).add(-1, SIZE).add(-SIZE * 2 - 1, SIZE), Style.NORMAL);
 
             Vector textPos = new Vector(-SIZE * 3, 0);
             graphic.drawText(textPos, textPos.add(1, 0), label, Orientation.RIGHTCENTER, Style.INOUT);