diff --git a/app/src/main/java/hatelace/instructions/Add.java b/app/src/main/java/hatelace/instructions/Add.java
index a81f1d9..76b3115 100644
--- a/app/src/main/java/hatelace/instructions/Add.java
+++ b/app/src/main/java/hatelace/instructions/Add.java
@@ -3,18 +3,19 @@ package hatelace.instructions;
 import hatelace.*;
 
 public class Add extends Instruction {
-    private Address op1;
-    private Word op2;
+    private Address src;
+    private Word imm;
     private Address dest;
 
-    public Add(Address op1, Word op2, Address dest) {
-        this.op1 = op1;
-        this.op2 = op2;
+    /** Add immediate value to memory address. */
+    public Add(Address src, Word imm, Address dest) {
+        this.src = src;
+        this.imm = imm;
         this.dest = dest;
     }
 
     public void execute(Memory memory, ProgramCounter PC) {
-        memory.write(this.dest, memory.read(this.op1).add(this.op2));
+        memory.write(this.dest, memory.read(this.src).add(this.imm));
         PC.incPC();
     }
 
@@ -23,6 +24,6 @@ public class Add extends Instruction {
     }
 
     protected Object[] operands() {
-        return new Object[] { this.op1, this.op2, this.dest };
+        return new Object[] { this.src, this.imm, this.dest };
     }
 }
diff --git a/app/src/main/java/hatelace/instructions/Copy.java b/app/src/main/java/hatelace/instructions/Copy.java
index d9c602f..9521879 100644
--- a/app/src/main/java/hatelace/instructions/Copy.java
+++ b/app/src/main/java/hatelace/instructions/Copy.java
@@ -3,16 +3,17 @@ package hatelace.instructions;
 import hatelace.*;
 
 public class Copy extends Instruction {
-    private Word word;
-    private Address address;
+    private Word imm;
+    private Address dest;
 
-    public Copy(Word word, Address address) {
-        this.word = word;
-        this.address = address;
+    /** Copy immediate value to memory address. */
+    public Copy(Word imm, Address dest) {
+        this.imm = imm;
+        this.dest = dest;
     }
 
     public void execute(Memory memory, ProgramCounter PC) {
-        memory.write(this.address, this.word);
+        memory.write(this.dest, this.imm);
         PC.incPC();
     }
 
@@ -21,6 +22,6 @@ public class Copy extends Instruction {
     }
 
     protected Object[] operands() {
-        return new Object[] {this.word, this.address};
+        return new Object[] {this.imm, this.dest};
     }
 }
diff --git a/app/src/main/java/hatelace/instructions/Halt.java b/app/src/main/java/hatelace/instructions/Halt.java
index 20804d9..569f868 100644
--- a/app/src/main/java/hatelace/instructions/Halt.java
+++ b/app/src/main/java/hatelace/instructions/Halt.java
@@ -3,6 +3,7 @@ package hatelace.instructions;
 import hatelace.*;
 
 public class Halt extends Instruction {
+    /** Halts the CPU */
     public Halt(){};
 
     public void execute(Memory memory, ProgramCounter PC) {
diff --git a/app/src/main/java/hatelace/instructions/Jump.java b/app/src/main/java/hatelace/instructions/Jump.java
index 4cd3b92..373dcb0 100644
--- a/app/src/main/java/hatelace/instructions/Jump.java
+++ b/app/src/main/java/hatelace/instructions/Jump.java
@@ -5,6 +5,7 @@ import hatelace.*;
 public class Jump extends Instruction {
     private int index;
 
+    /** Unconditional jump, non-relative */
     public Jump(int index) {
         this.index = index;
     }
diff --git a/app/src/main/java/hatelace/instructions/JumpEq.java b/app/src/main/java/hatelace/instructions/JumpEq.java
index 2491248..ecfc138 100644
--- a/app/src/main/java/hatelace/instructions/JumpEq.java
+++ b/app/src/main/java/hatelace/instructions/JumpEq.java
@@ -4,17 +4,18 @@ import hatelace.*;
 
 public class JumpEq extends Instruction {
     private int index;
-    private Address address;
-    private Word value;
+    private Address src;
+    private Word imm;
 
-    public JumpEq(int index, Address address, Word value) {
+    /** Conditional jump */
+    public JumpEq(int index, Address src, Word imm) {
         this.index = index;
-        this.address = address;
-        this.value = value;
+        this.src = src;
+        this.imm = imm;
     }
 
     public void execute(Memory memory, ProgramCounter PC) {
-        if (this.value.equals(memory.read(this.address))) {
+        if (this.imm.equals(memory.read(this.src))) {
             PC.setPC(this.index);
         } else {
             PC.incPC();
@@ -26,6 +27,6 @@ public class JumpEq extends Instruction {
     }
 
     protected Object[] operands() {
-        return new Object[] {this.index, this.address, this.value};
+        return new Object[] {this.index, this.src, this.imm};
     }
 }
diff --git a/app/src/main/java/hatelace/instructions/Mul.java b/app/src/main/java/hatelace/instructions/Mul.java
index c71f703..d70cb0b 100644
--- a/app/src/main/java/hatelace/instructions/Mul.java
+++ b/app/src/main/java/hatelace/instructions/Mul.java
@@ -3,18 +3,19 @@ package hatelace.instructions;
 import hatelace.*;
 
 public class Mul extends Instruction {
-    private Address op1;
-    private Address op2;
+    private Address src1;
+    private Address src2;
     private Address dest;
 
-    public Mul(Address op1, Address op2, Address dest) {
-        this.op1 = op1;
-        this.op2 = op2;
+    /** Multiply contents of two addresses and store the result in a third memory address. */
+    public Mul(Address src1, Address src2, Address dest) {
+        this.src1 = src1;
+        this.src2 = src2;
         this.dest = dest;
     }
 
     public void execute(Memory memory, ProgramCounter PC) {
-        memory.write(this.dest, memory.read(this.op1).multiply(memory.read(this.op2)));
+        memory.write(this.dest, memory.read(this.src1).multiply(memory.read(this.src2)));
         PC.incPC();
     }
 
@@ -23,6 +24,6 @@ public class Mul extends Instruction {
     }
 
     protected Object[] operands() {
-        return new Object[] {this.op1, this.op2, this.dest};
+        return new Object[] { this.src1, this.src2, this.dest };
     }
 }
diff --git a/app/src/main/java/hatelace/instructions/Print.java b/app/src/main/java/hatelace/instructions/Print.java
index 6aa3cec..88f0f6c 100644
--- a/app/src/main/java/hatelace/instructions/Print.java
+++ b/app/src/main/java/hatelace/instructions/Print.java
@@ -5,6 +5,7 @@ import hatelace.*;
 public class Print extends Instruction {
     private Address address;
 
+    /** Print content of memory address */
     public Print(Address address) {
         this.address = address;
     }