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Arisotura
Posted on 04-14-21 12:57 PM (rev. 15 of 04-14-21 11:01 PM) Link | #3582
command 94

replies with some sort of ID data?

example data from a Jam with the Band cart:

EC F1 00 95 40 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 EC 00 9E A1 51 65 34 35
30 35 30 31 19 19 02 0A 00 00 00 00 00 00 00 00
past that it's all zeroes.

the 16 bytes at 0x18 are also found at the beginning of the last 0x800 block in the save memory (which seems to be 8MB). the game checks for them.

EC 00 9E A1 51 65 34 35 30 35 30 31 19 19 02 0A
00 00 00 00 6D D6 DA 9B B0 24 22 88 79 3B BF EA
E6 AC 5E FA 69 12 0D 52 5D 5B F5 80 FF FF FF FF

command D6

retrieves the NAND status, repeated over and over again.

status values:
20 on init
bit5: NAND ready
bit4: write enable -- set by command 85, NOT cleared by command 84, cleared after a write/erase/etc command

command B2

seek somewhere? takes an address. doesn't seem to have any response.

after a B2 command, B7 reads from the savemem.

sets the 0x20000-byte window in which SRAM read/write is permitted. NAND stays stuck perma-busy if the address is before the start of the SRAM region (ROM header 94/96).

issuing this command while already in SRAM mode fucks shit up.

command 8B

reverts to regular ROM mode (B7 reads from ROM).

command 84

discard writebuffer. a subsequent cmd82 will have no effect.

command 85

write enable. sets bit4 in status register.

only works if SRAM mode (cmd B2) is engaged.

command 82

write disable. clears bit4 in status register.

required to finalize a write after using command 81 to send the data. (data presumably written from some temp buffer to the actual NAND)

write buffer is 0x800 bytes. not filling it enough fucks things up.

last 0x20000 block of the SRAM region is not writable. it's all FF except for the ID data at the beginning of the last 0x800 bytes.

____________________
Kuribo64


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