diff --git a/app/build.gradle.kts b/app/build.gradle.kts
index 4e2bfe9..b71b9f0 100644
--- a/app/build.gradle.kts
+++ b/app/build.gradle.kts
@@ -34,7 +34,7 @@ java {
 
 application {
     // Define the main class for the application.
-    mainClass.set("hatelace.App")
+    mainClass.set("hatelace.Main")
 }
 
 tasks.named<Test>("test") {
diff --git a/app/src/main/java/hatelace/Address.java b/app/src/main/java/hatelace/Address.java
new file mode 100644
index 0000000..913e50a
--- /dev/null
+++ b/app/src/main/java/hatelace/Address.java
@@ -0,0 +1,13 @@
+package hatelace;
+
+public class Address {
+    int address;
+
+    public Address(int address) {
+        this.address = address;
+    }
+
+    public int getAddress() {
+        return address;
+    }
+}
diff --git a/app/src/main/java/hatelace/IntMemory.java b/app/src/main/java/hatelace/IntMemory.java
new file mode 100644
index 0000000..99fb96c
--- /dev/null
+++ b/app/src/main/java/hatelace/IntMemory.java
@@ -0,0 +1,46 @@
+package hatelace;
+
+public class IntMemory extends Memory {
+    protected int[] memory;
+
+    public IntMemory() {
+        this.memory = new int[256];
+    }
+
+    public IntMemory(int size) {
+        this.memory = new int[size];
+    }
+
+    public int read(int address) {
+        return this.memory[address];
+    }
+
+    public int size() {
+        return this.memory.length;
+    }
+
+    public void write(int address, Word data) {
+        if (address < 0 || address >= this.memory.length) {
+            throw new IllegalArgumentException("Invalid memory address");
+        }
+        this.memory[address] = data.getValue();
+    }
+
+    /** Dump as IHEX-like format (see https://en.wikipedia.org/wiki/Intel_HEX) */
+    public void dump() {
+        for(int i = 0; i < this.memory.length; i+= 16) {
+            System.out.printf(":%02X%04X00 ", 16, i);
+            for(int j = 0; j < 16; j++) {
+                int content = this.memory[i + j];
+
+                // Print it as faded if it's zero
+                if (content == 0)
+                    System.out.print("\u001B[2m");
+
+                System.out.printf("%02X ", this.memory[i + j]);
+                System.out.print("\u001B[0m");
+            }
+            System.out.println();
+        }
+    }
+}
diff --git a/app/src/main/java/hatelace/IntWord.java b/app/src/main/java/hatelace/IntWord.java
new file mode 100644
index 0000000..286e337
--- /dev/null
+++ b/app/src/main/java/hatelace/IntWord.java
@@ -0,0 +1,29 @@
+package hatelace;
+
+public class IntWord extends Word {
+    private Integer value;
+
+    public IntWord(Integer value) {
+        this.value = value;
+    }
+
+    public <T> T getValue() {
+        return (T) value;
+    }
+
+    public <T> T add(Word other) {
+        return (T) new IntWord(value + (Integer) other.getValue());
+    }
+
+    public <T> T subtract(Word other) {
+        return (T) new IntWord(value - (Integer) other.getValue());
+    }
+
+    public <T> T multiply(Word other) {
+        return (T) new IntWord(value * (Integer) other.getValue());
+    }
+
+    public <T> T divide(Word other) {
+        return (T) new IntWord(value / (Integer) other.getValue());
+    }
+}
diff --git a/app/src/main/java/hatelace/App.java b/app/src/main/java/hatelace/Main.java
similarity index 74%
rename from app/src/main/java/hatelace/App.java
rename to app/src/main/java/hatelace/Main.java
index 357054b..dfaa036 100644
--- a/app/src/main/java/hatelace/App.java
+++ b/app/src/main/java/hatelace/Main.java
@@ -2,15 +2,16 @@ package hatelace;
 
 import hatelace.instructions.*;
 
-public class App {
+public class Main {
     public static void main(String[] args) {
         System.out.println("Starting...");
 
-        Memory memory = new Memory(64); // 64 words of memory
+        Memory memory = new IntMemory(64); // 64 words of memory
         Computer computer = new Computer(memory);
         Program program = new Program(new Instruction[] {
             new Add(1, 1, 0), // Store 1 + 1 in address 0
-            new Mul(2, 2, 1)  // Store 2 * 2 in address 1
+            new Mul(2, 2, 1),  // Store 2 * 2 in address 1
+            new Copy(new IntWord(3), new Address(2)) // Store 3 in address 2
         });
         computer.load(program);
         computer.run();
diff --git a/app/src/main/java/hatelace/Memory.java b/app/src/main/java/hatelace/Memory.java
index d8d07ba..b4aaa41 100644
--- a/app/src/main/java/hatelace/Memory.java
+++ b/app/src/main/java/hatelace/Memory.java
@@ -1,46 +1,10 @@
 package hatelace;
 
-public class Memory {
-    protected int[] memory;
-
-    public Memory() {
-        this.memory = new int[256];
-    }
-
-    public Memory(int size) {
-        this.memory = new int[size];
-    }
-
-    public int read(int address) {
-        return this.memory[address];
-    }
-
-    public int size() {
-        return this.memory.length;
-    }
-
-    public void write(int address, int data) {
-        if (address < 0 || address >= this.memory.length) {
-            throw new IllegalArgumentException("Invalid memory address");
-        }
-        this.memory[address] = data;
-    }
+public abstract class Memory {
+    public abstract int read(int address);
+    public abstract int size();
+    public abstract void write(int address, Word data);
 
     /** Dump as IHEX-like format (see https://en.wikipedia.org/wiki/Intel_HEX) */
-    public void dump() {
-        for(int i = 0; i < this.memory.length; i+= 16) {
-            System.out.printf(":%02X%04X00 ", 16, i);
-            for(int j = 0; j < 16; j++) {
-                int content = this.memory[i + j];
-
-                // Print it as faded if it's zero
-                if (content == 0)
-                    System.out.print("\u001B[2m");
-
-                System.out.printf("%02X ", this.memory[i + j]);
-                System.out.print("\u001B[0m");
-            }
-            System.out.println();
-        }
-    }
-}
+    public abstract void dump();
+}
\ No newline at end of file
diff --git a/app/src/main/java/hatelace/ProgramCounter.java b/app/src/main/java/hatelace/ProgramCounter.java
index b8b3b04..38dba7b 100644
--- a/app/src/main/java/hatelace/ProgramCounter.java
+++ b/app/src/main/java/hatelace/ProgramCounter.java
@@ -1,5 +1,6 @@
 package hatelace;
 
+/** Simple class to represent the Program Counter */
 public class ProgramCounter {
     private int PC;
 
diff --git a/app/src/main/java/hatelace/Word.java b/app/src/main/java/hatelace/Word.java
new file mode 100644
index 0000000..5f6d3bc
--- /dev/null
+++ b/app/src/main/java/hatelace/Word.java
@@ -0,0 +1,9 @@
+package hatelace;
+
+public abstract class Word {
+    public abstract <T> T getValue();
+    public abstract <T> T add(Word other);
+    public abstract <T> T subtract(Word other);
+    public abstract <T> T multiply(Word other);
+    public abstract <T> T divide(Word other);
+}
diff --git a/app/src/main/java/hatelace/instructions/Add.java b/app/src/main/java/hatelace/instructions/Add.java
index a5d2bad..9fa4959 100644
--- a/app/src/main/java/hatelace/instructions/Add.java
+++ b/app/src/main/java/hatelace/instructions/Add.java
@@ -3,6 +3,7 @@ package hatelace.instructions;
 import hatelace.Instruction;
 import hatelace.Memory;
 import hatelace.ProgramCounter;
+import hatelace.IntWord;
 
 public class Add extends Instruction {
     private int op1;
@@ -16,7 +17,7 @@ public class Add extends Instruction {
     }
 
     public void execute(Memory memory, ProgramCounter PC) {
-        memory.write(this.dest, this.op1 + this.op2);
+        memory.write(this.dest, new IntWord(this.op1 + this.op2));
         PC.incPC();
     }
 
diff --git a/app/src/main/java/hatelace/instructions/Copy.java b/app/src/main/java/hatelace/instructions/Copy.java
new file mode 100644
index 0000000..a1ce0dc
--- /dev/null
+++ b/app/src/main/java/hatelace/instructions/Copy.java
@@ -0,0 +1,30 @@
+package hatelace.instructions;
+
+import hatelace.Address;
+import hatelace.Word;
+import hatelace.Memory;
+import hatelace.ProgramCounter;
+import hatelace.Instruction;
+
+public class Copy extends Instruction {
+    private Word word;
+    private Address address;
+
+    public Copy(Word word, Address address) {
+        this.word = word;
+        this.address = address;
+    }
+
+    public void execute(Memory memory, ProgramCounter PC) {
+        memory.write(this.address.getAddress(), this.word);
+        PC.incPC();
+    }
+
+    protected String opcode() {
+        return "copy";
+    }
+
+    protected Object[] operands() {
+        return new Object[] {this.word, this.address};
+    }
+}
diff --git a/app/src/main/java/hatelace/instructions/Mul.java b/app/src/main/java/hatelace/instructions/Mul.java
index a749e6c..4a88590 100644
--- a/app/src/main/java/hatelace/instructions/Mul.java
+++ b/app/src/main/java/hatelace/instructions/Mul.java
@@ -3,6 +3,7 @@ package hatelace.instructions;
 import hatelace.Instruction;
 import hatelace.Memory;
 import hatelace.ProgramCounter;
+import hatelace.IntWord;
 
 public class Mul extends Instruction {
     private int op1;
@@ -16,7 +17,7 @@ public class Mul extends Instruction {
     }
 
     public void execute(Memory memory, ProgramCounter PC) {
-        memory.write(this.dest, this.op1 * this.op2);
+        memory.write(this.dest, new IntWord(this.op1 * this.op2));
         PC.incPC();
     }