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--- notes:homebrew:gba_nds_slot2 [2023/03/28 17:56] – removed - external edit (Unknown date) 127.0.0.1
+++ notes:homebrew:gba_nds_slot2 [2023/03/28 17:56] (current) – ↷ Page name changed from notes:homebrew:flashtek to notes:homebrew:gba_nds_slot2 asie
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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?