diff --git a/eu.heili/AndGate.java b/eu.heili/AndGate.java
index 1fc995b..a56d59c 100644
--- a/eu.heili/AndGate.java
+++ b/eu.heili/AndGate.java
@@ -7,6 +7,8 @@ public class AndGate extends LogicGate {
 
     public AndGate(final DigitalInput... inputvals) {
         super(inputvals);
+        if (inputvals.length > 8)
+            throw (new TooManyInputsException());
     }
 
     @Override
diff --git a/eu.heili/EnxorGate.java b/eu.heili/EnxorGate.java
index f92acc7..3151b5e 100644
--- a/eu.heili/EnxorGate.java
+++ b/eu.heili/EnxorGate.java
@@ -1,2 +1,14 @@
-public class EnxorGate {
+public class EnxorGate extends ExorGate{
+    public EnxorGate(int inputnr) {
+        super(inputnr);
+    }
+
+    public EnxorGate(DigitalInput... inputvals) {
+        super(inputvals);
+    }
+
+    @Override
+    public boolean getOutput() {
+        return !super.getOutput();
+    }
 }
diff --git a/eu.heili/ExorGate.java b/eu.heili/ExorGate.java
index bebc130..2757b8a 100644
--- a/eu.heili/ExorGate.java
+++ b/eu.heili/ExorGate.java
@@ -1,2 +1,24 @@
-public class ExorGate {
+public class ExorGate extends LogicGate {
+    public ExorGate(int inputnr) {
+        super(inputnr);
+        if (inputnr > 2)
+            throw (new TooManyInputsException());
+    }
+
+    public ExorGate(DigitalInput... inputvals) {
+        super(inputvals);
+        if (inputvals.length > 2)
+            throw (new TooManyInputsException());
+    }
+
+    @Override
+    public boolean getOutput() {
+        boolean first = getInput(0).getValue();
+        for (int i = 1; i < getInputNumber(); i++) {
+            if (getInput(i).getValue() != first)
+                return true; // if there is one change return true
+            first = getInput(i).getValue();
+        }
+        return false; // all values are the same...
+    }
 }
diff --git a/eu.heili/Main.java b/eu.heili/Main.java
index a8f96e4..8881345 100644
--- a/eu.heili/Main.java
+++ b/eu.heili/Main.java
@@ -1,7 +1,6 @@
 public class Main {
     public static void main(String[] args) {
-        System.out.println("bla");
-
+        // teacher example:
         OrGate o1 = new OrGate(2);
         AndGate a2 = new AndGate(2);
         // Verbinde Eingang 0 mit dem Ausgang vom OR - Gate.
@@ -13,12 +12,69 @@ public class Main {
         // Setze Eingang 1 auf 1.
         o1.getInput(1).setValue(0);
 
+
+        /** some definition tests with better syntax (; */
         AndGate gt = new AndGate(
-                new DigitalInput(false),
+                new DigitalInput(0),
                 new DigitalInput(true),
                 new DigitalInput(o1),
-                new DigitalInput('H'));
+                new DigitalInput('H')
+        );
 
-        System.out.println(a2.getOutput());
+        LogicGate or = new AndGate(
+                new DigitalInput(0),
+                new DigitalInput(1)
+        );
+        System.out.println(or.getOutput());
+
+        LogicGate nor = new NandGate(
+                new DigitalInput(0),
+                new DigitalInput(1)
+        );
+
+
+        /** bsp 1 **/
+
+        boolean x = false;
+        boolean y = true;
+
+        LogicGate s = new OrGate(
+                new DigitalInput(new AndGate(
+                        new DigitalInput(new NotGate(
+                                new DigitalInput(x)
+                        )),
+                        new DigitalInput(y)
+                )),
+                new DigitalInput(new AndGate(
+                        new DigitalInput(x),
+                        new DigitalInput(new NotGate(
+                                new DigitalInput(y)
+                        ))
+                ))
+        );
+
+        LogicGate c = new AndGate(
+                new DigitalInput(x),
+                new DigitalInput(y)
+        );
+        System.out.println("Bsp1");
+        System.out.println("output of c: " + c.getOutput());
+        System.out.println("output of s: " + s.getOutput());
+
+        /** bsp. 2 **/
+        boolean xx = true;
+        boolean yy = false;
+
+        LogicGate ss = new ExorGate(
+                new DigitalInput(xx),
+                new DigitalInput(yy)
+        );
+        LogicGate cc = new AndGate(
+                new DigitalInput(xx),
+                new DigitalInput(yy)
+        );
+        System.out.println("Bsp2");
+        System.out.println("output of c: " + cc.getOutput());
+        System.out.println("output of s: " + ss.getOutput());
     }
 }
\ No newline at end of file
diff --git a/eu.heili/NandGate.java b/eu.heili/NandGate.java
new file mode 100644
index 0000000..7112836
--- /dev/null
+++ b/eu.heili/NandGate.java
@@ -0,0 +1,14 @@
+public class NandGate extends AndGate{
+    public NandGate(int inputnr) {
+        super(inputnr);
+    }
+
+    public NandGate(DigitalInput... inputvals) {
+        super(inputvals);
+    }
+
+    @Override
+    public boolean getOutput() {
+        return !super.getOutput();
+    }
+}
diff --git a/eu.heili/NorGate.java b/eu.heili/NorGate.java
index 796540e..14e2ff1 100644
--- a/eu.heili/NorGate.java
+++ b/eu.heili/NorGate.java
@@ -1,2 +1,14 @@
-public class NorGate {
+public class NorGate extends OrGate{
+    public NorGate(int inputnr) {
+        super(inputnr);
+    }
+
+    public NorGate(DigitalInput... inputvals) {
+        super(inputvals);
+    }
+
+    @Override
+    public boolean getOutput() {
+        return !super.getOutput();
+    }
 }
diff --git a/eu.heili/NotGate.java b/eu.heili/NotGate.java
index 5fe7711..5877212 100644
--- a/eu.heili/NotGate.java
+++ b/eu.heili/NotGate.java
@@ -1,2 +1,14 @@
-public class NotGate {
+public class NotGate extends LogicGate{
+    public NotGate() {
+        super(1);
+    }
+
+    public NotGate(DigitalInput inputval) {
+        super(inputval);
+    }
+
+    @Override
+    public boolean getOutput() {
+        return !getInput(0).getValue();
+    }
 }
diff --git a/eu.heili/OrGate.java b/eu.heili/OrGate.java
index c3b60d5..4dd73e5 100644
--- a/eu.heili/OrGate.java
+++ b/eu.heili/OrGate.java
@@ -1,10 +1,14 @@
 public class OrGate extends LogicGate {
     public OrGate(final int inputnr) {
         super(inputnr);
+        if (inputnr > 8)
+            throw (new TooManyInputsException());
     }
 
     public OrGate(final DigitalInput... inputvals) {
         super(inputvals);
+        if (inputvals.length > 8)
+            throw (new TooManyInputsException());
     }
 
     @Override