diff --git a/hal/module.go b/hal/module.go
index 09ded49..a218b1e 100644
--- a/hal/module.go
+++ b/hal/module.go
@@ -10,6 +10,7 @@ type Module struct {
 	Accumulator    float64
 	ProgramStorage Program
 	Register       []float64
+	IO             []float64
 	isStopped      bool
 }
 
@@ -40,12 +41,13 @@ func (h *Module) Run() error {
 	return nil
 }
 
-func NewHALModule(program Program, registerSize uint64) (*Module, error) {
+func NewHALModule(program Program, registerSize uint64, ioSize uint64) (*Module, error) {
 	if registerSize <= 10 {
 		return nil, fmt.Errorf("register size must be greater then 10 [ registerSize = %d ]", registerSize)
 	}
 	return &Module{
 		ProgramStorage: program,
 		Register:       make([]float64, registerSize),
+		IO:             make([]float64, ioSize),
 	}, nil
 }