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====== GBA/NDS Slot-2 peripheral programming notes ======

===== Compact Flash Adapters =====

Compact Flash adapters on the GBA cartridge interface all generally work by exposing IDE registers using the top eight address bits coupled with the sixteen-bit data bus, wiring them directly to the relevant IDE connector pins.

In programmer-facing documentation, the two address ranges mentioned (matching PC I/O) are 1F0h-1F7h and 3F0-3F7h. In hardware, the choice is controled by Chip Select (CS) pins, while the specific register is chosen using DA0-DA2.

TODO:

  * Is INTRQ relayed in any way? On which adapters?

==== GBA Movie Player ====

^ Address bits ^ Map to ^
| 23 | "1" |
| 22 | Chip Select 0/1 |
| 18-16 | DA2-DA0 |

===== Memory Expansion Pak =====

Identification:

  * 0B4h (device type) == 24h
  * 0BFh - bit 7 clear
  * 1FFFFh - bit 7 clear

Timings:

  * Official software uses default timings (EXMEMCNT[6:0] = 00h).

Memory map:

  * 240000h - unlock register (32-bit)
    * bit 0 - set if unlocked, clear if locked
    * bit 1-31 - unknown
  * 1000000h - 8 megabytes of memory starts here

TODO:

  * what are the remaining unlock register bits?
    * official software crashes if any bits 16-31 are set on initialization
  * does the unlock register control memory visibility or just writability?