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External Hardware IO Address Map

From CoCopedia - The Tandy/Radio Shack Color Computer Wiki
Revision as of 21:05, 13 April 2026 by Barberd (talk | contribs)
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Tandy designated IO addresses from $FF60 to $FF7F for add-on hardware, but several parties chose to build in the $FF40-$FF5F and $FF80-FF8F ranges as well. Here are known IO addresses for add-on hardware.

Note some devices overlap each other; these devices will conflict and cannot be used together without modification.

Built-in IO devices:

  • $FF00-FF3F PIA Used for Keyboard, Joystick, Serial Port, Cassette, FIRQ, Sound, Horizontal and Vertical Sync Interrupts, Video Display Generator modes
  • $FF90-FFBF GIME Used for memory management unit (MMU) configuration, coco3 video modes/color palette/resolution, coco3 interrupt and fast interrupt controls, and timers
  • $FFC0-FFDF SAM Used to set clock speed, Video Display Generator modes and memory location/size, and RAM/ROM mode