The system ROM (often called BIOS) is a ROM containing code for the 68k startup program, some lookup tables, and various generic functions which can or must be used by games. They are present in all NeoGeo hardware types in various versions. The NeoGeo CD system ROMs also contains graphics, sound, and Z80 code.
Original system ROMs have their nationality set by the byte at address $000401 (0=Japan, 1=US, 2=Euro), and their type set by the byte at $000400 (0=AES, $80=MVS).
Through-hole ROMs can be replaced by 27C1024 or TC571024D EPROMs.
Copied from [MAME's source].
|SP-S||Europe MVS (V1)||C7F2FA45||09576FF20B4D6B365E78E6A5698EA450262697CD|
|SP-S2||Europe MVS (V2)||9036D879||4F5ED7105B7128794654CE82B51723E16E389543|
|SP-E||US MVS (V1)||2723A5B5||5DBFF7531CF04886CDE3EF022FB5CA687573DCB8|
|SP-U2||US MVS (V2?)||E72943DE||5C6BBA07D2EC8AC95776AA3511109F5E1E2E92EB|
|V2||US MVS (4-slot V2)||62F021F4||62D372269E1B3161C64AE21123655A0A22FFD1BB|
|ASIA-S3||Asia MVS (V3)||91B64BE3||720A3E20D26818632AEDF2C2FD16C54F213543E1|
|VS-BIOS||Japan MVS (V3)||F0E8F27D||ECF01EDA815909F1FACEC62ABF3594EAA8D11075|
|SP-J2||Japan MVS (V2)||ACEDE59C||B6F97ACD282FD7E94D9426078A90F059B5E9DD91|
|SP1||Japan MVS (V1)||9FB0ABE4||18A987CE2229DF79A8CF6A84F968F0E42CE4E59D|
|SP-45||Asia MVS (V4.5)||03CC9F6A||CDF1F49E3FF2BAC528C21ED28449CF35B7957DC1|
|JAPAN-J3||Japan MVS (V3)||DFF6D41F||E92910E20092577A4523A6B39D578A71D4DE7085|
|SP-1V1||Hotel unit (V1.3)||162F0EBE||FE1C6DD3DFCF97D960065B1BB46C1E11CB7BF271|
The system ROM is always mapped at $C00000.
Size: 128KiB. Named NEO-P0 (Japan) or NEO-EP0 (Export).
Size: 128KiB. Often named "SP" for System Program. Many different versions.
SPJ Japanese system ROM on a ROM-only arcade board.
On CD systems, the system ROM contains Z80 and 68k programs, ADPCM sound, and graphics which are loaded to the corresponding DRAMs at startup. There are no SFIX or SM1 ROMs in CD systems (but still a LO ROM).
- FRONT-SP1 (Front loaders)
- TOP-SP1 (Early top loaders using LC8953)
- TOP-SP1-2 (Late top loaders using LC98000)
- TOP-SPD (CDZ)
The CD1 and CD2 system ROMs contain credits organized to be displayed on the fix layer (how can this be seen ?):
- Noriyuki Higashi is "Mr.Noric".
- Toshiya Yahara is cited as the inventor of the NeoGeo Pocket power supply in an SNK patent.
- Jo(h)n Guso is credited as a programmer in several games.
The CDZ version includes the "Ver 3.0 by MAKOTO.04/03/10 to SK" driver.
Opensource AES/MVS system ROM in development. See Neopen BIOS.