NEO-SMA
Info from [MAME's source]
QFP144 chip found connected to the P ROMs in some The King of Fighters '99 - Millennium Battle, The King of Fighters 2000, Metal Slug 3 and in all (?) Garou - Mark of the Wolves cartridges. Bankswitches the second megabyte ($200000~$2FFFFF) of P ROM space and provides a 16bit pseudo random number generator.
Upon system reset, the PRN is initialized to $2345.
The chip always (?) replies $9A37 on reads.
PRN
16bit LSFR with taps at bits 2,3,5,6,7,11,12,15. Each read steps the register.
Bankswitching
Bankswitching is done by unscrambling the written bank number and using a 64 entry (256 bytes) lookup table to map the P ROM into $200000~$2FFFFF.
KOF 99
- Bankswitching write at $2FFFF1
- Read chip presence at $2FE447
- PRN at $2FFFF8 and $2FFFFA
Bankswitch LUT (P2 ROM address):
| 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | A | B | C | D | E | F | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 0 | $000000 | $100000 | $200000 | $300000 | $3CC000 | $4CC000 | $3F2000 | $4F2000 | $407800 | $507800 | $40D000 | $50D000 | $417800 | $517800 | $420800 | $520800 |
| 1 | $424800 | $524800 | $429000 | $529000 | $42E800 | $52E800 | $431800 | $531800 | $54D000 | $551000 | $567000 | $592800 | $588800 | $581800 | $599800 | $594800 |
| 2 | $598000 | ? | ? | ? | ? | ? | ? | ? | ? | ? | ? | ? | ? | ? | ? | ? |
Garou
- Bankswitching write at $2FFFC0
- Read chip presence at $2FE447
- PRN at $2FFFCC and $2FFFF0
Metal Slug 3
- Bankswitching write at $2FFFE5
- Read chip presence at $2FE447
- PRN at $2FFFF8 and $2FFFFA
Bankswitch LUT (P2 ROM address):
| 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | A | B | C | D | E | F | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 0 | $000000 | $020000 | $040000 | $060000 | $070000 | $090000 | $0B0000 | $0D0000 | $0E0000 | $0F0000 | $120000 | $130000 | $140000 | $150000 | $180000 | $190000 |
| 1 | $1A0000 | $1B0000 | $1E0000 | $1F0000 | $200000 | $210000 | $240000 | $250000 | $260000 | $270000 | $2A0000 | $2B0000 | $2C0000 | $2D0000 | $300000 | $310000 |
| 2 | $320000 | $330000 | $360000 | $370000 | $380000 | $390000 | $3C0000 | $3D0000 | $400000 | $410000 | $440000 | $450000 | $460000 | $470000 | $4A0000 | $4B0000 |
| 3 | $4C0000 | ? | ? | ? | ? | ? | ? | ? | ? | ? | ? | ? | ? | ? | ? | ? |
KOF 2000
- Bankswitching write at $2FFFED
- Read chip presence at $2FE447
- PRN at $2FFFD8 and $2FFFDA
Bankswitch LUT (P2 ROM address):
| 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | A | B | C | D | E | F | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 0 | $000000 | $100000 | $200000 | $300000 | $3F7800 | $4F7800 | $3FF800 | $4FF800 | $407800 | $507800 | $40F800 | $50F800 | $416800 | $516800 | $41D800 | $51D800 |
| 1 | $424000 | $524000 | $523800 | $623800 | $526000 | $626000 | $528000 | $628000 | $52A000 | $62A000 | $52B800 | $62B800 | $52D000 | $62D000 | $52E800 | $62E800 |
| 2 | $618000 | $619000 | $61A000 | $61A800 | ? | ? | ? | ? | ? | ? | ? | ? | ? | ? | ? | ? |