Changes
bit 7: memory card wait state control: 1 for wait states, 0 for no wait
bit 0: NEC765 Terminal Count input (1=TC active, 0=TC inactive)
bit 2: Backlight: 1=off, 0=on
bit 0: on/off control: 1 = on, 0 = off
Address = 80
centronics status
bit 0: busy state
Address = A0
