diff --git a/acia6551.go b/acia6551.go
new file mode 100644
index 0000000..ffcbc80
--- /dev/null
+++ b/acia6551.go
@@ -0,0 +1,28 @@
+package i6502
+
+/*
+ACIA 6551 Serial IO
+*/
+type Acia6551 struct {
+	rx chan byte // Reading (Acia Input) line
+	tx chan byte // Transmitting (Acia Output) line
+}
+
+func NewAcia6551(rx chan byte, tx chan byte) (*Acia6551, error) {
+	return &Acia6551{tx: tx, rx: rx}, nil
+}
+
+func (r *Acia6551) Size() uint16 {
+	// We have a only 4 addresses, RX, TX, Command and Control
+	return 0x04
+}
+
+/*
+func (r *Rom) Read(address uint16) byte {
+	return r.data[address]
+}
+
+func (r *Rom) Write(address uint16, data byte) {
+	panic(fmt.Errorf("Trying to write to ROM at 0x%04X", address))
+}
+*/
diff --git a/acia6551_test.go b/acia6551_test.go
new file mode 100644
index 0000000..9e19e15
--- /dev/null
+++ b/acia6551_test.go
@@ -0,0 +1,15 @@
+package i6502
+
+import (
+	"github.com/stretchr/testify/assert"
+	"testing"
+)
+
+func TestNewAcia6551(t *testing.T) {
+	tx := make(chan byte)
+	rx := make(chan byte)
+	acia, err := NewAcia6551(rx, tx)
+
+	assert.Nil(t, err)
+	assert.Equal(t, 0x4, acia.Size())
+}