NEO-SMA

NEO-SMA chip found in a MVS cartridge. Picture courtesy of [MVS-Scans].

Info from [MAME's source]

QFP144 chip found connected to the P ROMs in The King of Fighters '99 - Millennium Battle (not all sets), The King of Fighters 2000 (not all sets), Metal Slug 3 (not all sets) and in Garou - Mark of the Wolves (all sets) 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	?	?	?	?	?	?	?	?	?	?	?	?	?	?	?
3	?	?	?	?	?	?	?	?	?	?	?	?	?	?	?	?

Garou

• Bankswitching write at $2FFFC0
• Read chip presence at $2FE447
• PRN at $2FFFCC and $2FFFF0

garou / "KF" chip revision:

Bank scambling=12,14,6,7,9,5

	0	1	2	3	4	5	6	7	8	9	A	B	C	D	E	F
0	$000000	$100000	$200000	$300000	$280000	$380000	$2D0000	$3D0000	$2F0000	$3F0000	$400000	$500000	$420000	$520000	$440000	$540000
1	$498000	$598000	$4A0000	$5A0000	$4A8000	$5A8000	$4B0000	$5B0000	$4B8000	$5B8000	$4C0000	$5C0000	$4C8000	$5C8000	$4D0000	$5D0000
2	$458000	$558000	$460000	$560000	$468000	$568000	$470000	$570000	$478000	$578000	$480000	$580000	$488000	$588000	$490000	$590000
3	$5D0000	$5D8000	$5E0000	$5E8000	$5F0000	$5F8000	$600000	?	?	?	?	?	?	?	?	?

garouo / "KE" chip revision:

Bank scambling=13,11,2,14,8,4

	0	1	2	3	4	5	6	7	8	9	A	B	C	D	E	F
0	$000000	$100000	$200000	$300000	$280000	$380000	$2D0000	$3D0000	$2C8000	$3C8000	$400000	$500000	$420000	$520000	$440000	$540000
1	$598000	$698000	$5A0000	$6A0000	$5A8000	$6A8000	$5B0000	$6B0000	$5B8000	$6B8000	$5C0000	$6C0000	$5C8000	$6C8000	$5D0000	$6D0000
2	$458000	$558000	$460000	$560000	$468000	$568000	$470000	$570000	$478000	$578000	$480000	$580000	$488000	$588000	$490000	$590000
3	$5D8000	$6D8000	$5E0000	$6E0000	$5E8000	$6E8000	$6E8000	$000000	$000000	$000000	$000000	$000000	$000000	$000000	$000000	$000000

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	?	?	?	?	?	?	?	?	?	?	?	?
3	?	?	?	?	?	?	?	?	?	?	?	?	?	?	?	?