diff --git a/hal/instructions.go b/hal/instructions.go
index ceed661..3e43777 100644
--- a/hal/instructions.go
+++ b/hal/instructions.go
@@ -58,8 +58,8 @@ var InstructionStop = &Instruction{
 
 var InstructionOut = &Instruction{
 	Name: "OUT",
-	Execute: func(module *Module) {
-		// TODO implement
+	ExecuteWithOperand: func(module *Module, operand float64) {
+		module.IO[int64(operand)] = module.accumulator
 	},
 }
 
diff --git a/hal/module.go b/hal/module.go
index a218b1e..04b1db8 100644
--- a/hal/module.go
+++ b/hal/module.go
@@ -7,23 +7,23 @@ const maxInstructions = 1000
 type Program map[int64]*ProgrammedInstruction
 
 type Module struct {
-	Accumulator    float64
-	ProgramStorage Program
-	Register       []float64
+	accumulator    float64
+	programStorage Program
+	register       []float64
 	IO             []float64
 	isStopped      bool
 }
 
 func (h *Module) ProgramCounter() int64 {
-	return int64(h.Register[0])
+	return int64(h.register[0])
 }
 
 func (h *Module) increaseProgramCounter() {
-	h.Register[0]++
+	h.register[0]++
 }
 
 func (h *Module) Step() {
-	instruction := h.ProgramStorage[h.ProgramCounter()]
+	instruction := h.programStorage[h.ProgramCounter()]
 	h.increaseProgramCounter()
 	if instruction == nil {
 		return
@@ -46,8 +46,8 @@ func NewHALModule(program Program, registerSize uint64, ioSize uint64) (*Module,
 		return nil, fmt.Errorf("register size must be greater then 10 [ registerSize = %d ]", registerSize)
 	}
 	return &Module{
-		ProgramStorage: program,
-		Register:       make([]float64, registerSize),
+		programStorage: program,
+		register:       make([]float64, registerSize),
 		IO:             make([]float64, ioSize),
 	}, nil
 }