To unlock this register, one must write 0xA55A to it first.
15 bit 0
---- ---- ---- ----
???? ???? ???? ?wsm
|||
||+- Map registers
|+-- CF/SD enable
+--- PSRAM write enable
Also swaps SRAM bank (2 x 64 KB)
For CompactFlash card access, the SuperCard CF mimics the GBA Movie Player interface.
SD card 4-bit data bus writes.
15 bit 0 ---- ---- ---- ---- oooo .... .... .... |||| ++++---------------- Written value.
SD card 4-bit data bus reads.
TODO: Most likely operates as a 16-bit shift register. This means that, to read sixteen bits in order, the address must be accessed four times.
15 bit 0 ---- ---- ---- ---- oooo .... .... .... |||| ++++---------------- Written value.
SD card 1-bit command bus.
15 bit 0
---- ---- ---- ----
.... ..?? o... ...i
|| | |
|| | +- Input (from card)
|| |
|| +--------- Output (to card)
||
++----------- Related to card insertion?