diff --git a/distribution/ReleaseNotes.txt b/distribution/ReleaseNotes.txt
index a1880a35f..ba2c24bcf 100644
--- a/distribution/ReleaseNotes.txt
+++ b/distribution/ReleaseNotes.txt
@@ -7,6 +7,8 @@ HEAD, planned as v0.31
 - Allows disabling LED's in the measurement graph
 - Adds drivers with inverted output
 - Adds a minified circuit as a new shape for embedded circuits
+- Highlights the input connection port in the multiplexer when the
+  input is selected.
 - Allows recovering from oscillations.
 - Supports XDG_CONFIG_HOME environment variable
 - Fixes a bug in max path len calculation
diff --git a/src/main/dig/processor/Processor.dig b/src/main/dig/processor/Processor.dig
index 91bfdb125..d0c36047f 100644
--- a/src/main/dig/processor/Processor.dig
+++ b/src/main/dig/processor/Processor.dig
@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="utf-8"?>
 <circuit>
-  <version>1</version>
+  <version>2</version>
   <attributes>
     <entry>
       <string>Description</string>
@@ -158,10 +158,6 @@ Single-Cycle CPU.}}</string>
     <visualElement>
       <elementName>Clock</elementName>
       <elementAttributes>
-        <entry>
-          <string>runRealTime</string>
-          <boolean>true</boolean>
-        </entry>
         <entry>
           <string>Label</string>
           <string>Clock</string>
@@ -777,13 +773,15 @@ Single-Cycle CPU.}}</string>
         </entry>
         <entry>
           <string>Data</string>
-          <data>8000,961,8190,951,a90,a83,a25,a3a,10e1,afc,2bef,3d5f,c21,212f,38f9,3d20,105,116,a30,
-a20,aa0,8035,3ac0,4380,2180,3505,2172,3505,2173,3503,3d03,2173,3801,aa3,401a,c01,
-c11,c21,8014,2020,38eb,c31,8014,2030,38e6,1991,ffff,3e09,146,165,154,4400,3ddb,a70,
-1031,8014,f00,8060,3ab0,c21,c01,8060,3ab0,c31,8014,b00,8060,3ab0,c31,8014,b00,8060,
-3ab0,1021,1001,8060,3ab0,1021,1001,8060,3ab0,1031,8014,f00,8060,3ab0,1031,8014,f00,
-8060,3ab0,c21,c31,8015,b00,3b0c,8014,2020,3707,8014,2030,3704,4380,2180,3501,c71,
-3b0b,143,8014,1c40,242,246,4048,2cfe,ce1,3b0f</data>
+          <data>8000,961,8190,951,a90,a83,a25,a3a,10e1,afc,2bef,3d5f,c21,212f
+,38f9,3d20,105,116,a30,a20,aa0,8035,3ac0,4380,2180,3505,2172,3505
+,2173,3503,3d03,2173,3801,aa3,401a,c01,c11,c21,8014,2020,38eb
+,c31,8014,2030,38e6,1991,ffff,3e09,146,165,154,4400,3ddb,a70,1031
+,8014,f00,8060,3ab0,c21,c01,8060,3ab0,c31,8014,b00,8060,3ab0,c31
+,8014,b00,8060,3ab0,1021,1001,8060,3ab0,1021,1001,8060,3ab0,1031
+,8014,f00,8060,3ab0,1031,8014,f00,8060,3ab0,c21,c31,8015,b00,3b0c
+,8014,2020,3707,8014,2030,3704,4380,2180,3501,c71,3b0b,143,8014
+,1c40,242,246,4048,2cfe,ce1,3b0f</data>
         </entry>
         <entry>
           <string>lastDataFile</string>
diff --git a/src/main/java/de/neemann/digital/draw/shapes/MuxerShape.java b/src/main/java/de/neemann/digital/draw/shapes/MuxerShape.java
index 862263f3f..13baf46ca 100644
--- a/src/main/java/de/neemann/digital/draw/shapes/MuxerShape.java
+++ b/src/main/java/de/neemann/digital/draw/shapes/MuxerShape.java
@@ -5,6 +5,8 @@
  */
 package de.neemann.digital.draw.shapes;
 
+import de.neemann.digital.core.ObservableValue;
+import de.neemann.digital.core.Value;
 import de.neemann.digital.core.element.ElementAttributes;
 import de.neemann.digital.core.element.Keys;
 import de.neemann.digital.core.element.PinDescriptions;
@@ -14,6 +16,7 @@
 import de.neemann.digital.draw.graphics.*;
 
 import static de.neemann.digital.draw.shapes.GenericShape.SIZE;
+import static de.neemann.digital.draw.shapes.GenericShape.SIZE2;
 
 /**
  * The Muxer shape
@@ -24,6 +27,8 @@ public class MuxerShape implements Shape {
     private final PinDescriptions inputs;
     private final PinDescriptions outputs;
     private Pins pins;
+    private ObservableValue selector;
+    private Value selectorValue;
 
     /**
      * Creates a new instance
@@ -58,9 +63,16 @@ public Pins getPins() {
 
     @Override
     public Interactor applyStateMonitor(IOState ioState) {
+        selector = ioState.getInput(0);
         return null;
     }
 
+    @Override
+    public void readObservableValues() {
+        if (selector != null)
+            selectorValue = selector.getCopy();
+    }
+
     @Override
     public void drawTo(Graphic graphic, Style heighLight) {
         graphic.drawPolygon(new Polygon(true)
@@ -69,5 +81,15 @@ public void drawTo(Graphic graphic, Style heighLight) {
                 .add(SIZE * 2 - 1, inputCount * SIZE - 5)
                 .add(1, inputCount * SIZE + 4), Style.NORMAL);
         graphic.drawText(new Vector(3, 2), "0", Orientation.LEFTTOP, Style.SHAPE_PIN);
+
+        if (selectorValue != null) {
+            int in = (int) selectorValue.getValue() + 1;
+            Pins p = getPins();
+            if (in < p.size()) {
+                Vector pos = p.get(in).getPos();
+                int s = SIZE2 / 2;
+                graphic.drawCircle(pos.add(-s, -s), pos.add(s, s), Style.THIN);
+            }
+        }
     }
 }