{| class="wikitable"
!I/O address
!/CS (A11)!A1 (A9)!A0 (A8)
!Description
!Read/Write status
!Used for
|-
|&F4xx||0||0||0||Port A Data||Read/Write||In/Out||[[PSG]] (Sound/Keyboard/Joystick)
|-
|&F5xx||0||0||1||Port B Data||Read/Write||In||Vsync/Jumpers/PrinterBusy/CasIn/Exp
|-
|&F6xx||0||1||0||Port C Data||Read/Write||Out||KeybRow/CasOut/PSG
|-
|&F7xx||0||1||1||Control||Write Only||Out||Control
|-
|}