Acorn AKA12 User Port MIDI Upgrade

Register description

IOC address map :
  0000-1fff - ROM
  2000-2fff - 6522 VIA
    PA0-PA2 - ROM bank
  3000-3fff - SCC2691 UART

Notes

Expansion card header is at ROM address 0x3800 (ROM bank 7). VIA port A is set to all input on reset, which results in the ROM high bits being pulled high. The loader will switch PA0-PA2 between input to read the header and chunk directory, and output to read module data.

Links

Chris's Acorns: Acorn AKA12 MIDI