pkg/appleone: add a public appleone pkg

Move cpu and opcodes (cpu package) to internal, while adding a public
appleone api package to `pkg/`

internal/cpu/cpu.go

@@ -48,7 +48,8 @@ const (
 	zeroPageYIndexed
 )
 
-type mos6502cpu struct {
+// Mos6502 TODO: docs
+type Mos6502 struct {
 	pc uint16 // program counter (16 bit)
 	ac uint8  // accumulator (8 bit)
 	x  uint8  // X register (8 bit)
@@ -56,3 +57,8 @@ type mos6502cpu struct {
 	sr uint8  // status register [NV-BDIZC] (8 bit)
 	sp uint8  // stack pointer (8 bit)
 }
+
+// New TODO: docs
+func New() *Mos6502 {
+	return &Mos6502{}
+}

pkg/appleone/appleone.go

@@ -0,0 +1,13 @@
+package appleone
+
+import "github.com/bradford-hamilton/apple-1/internal/cpu"
+
+// Appleone TODO docs
+type Appleone struct {
+	cpu *cpu.Mos6502
+}
+
+// New TODO: docs
+func New() *Appleone {
+	return &Appleone{cpu: cpu.New()}
+}