System ROM



BIOSes (officially called "SYSTEM ROM") are ROMs containing the 68k startup program and various generic functions for NeoGeo systems. They are present in all hardware types in various versions. The NeoGeo CD BIOSes also contain graphics, sound, and Z80 code.

The official BIOSes have their nationality set by the byte at address $C00401 (0=Japan, 1=US, 2=Euro).

The type is set by the byte at $C00400 (0=AES, $80=MVS).

Included tables

 * $C02000: METRIC_DATA (?, $2000)
 * $C04000: Sinus table (words, signed $200)
 * $C04200: Random table ($100)

AES BIOS
Size: 128KiB. Called "NEO-EP0".



MVS BIOS


Size: 128KiB. Called "SP-S2", "SP-E"... Different names according to nationality.

Graphic visualisation of sp-s2.bin:



CD/CDZ BIOS




Size: 512KiB.

ROM chip that contains Z80 and 68k programs, PCM sound, and graphics which are copied to the corresponding DRAMs at boot time. There is no SFIX or SM1 ROMs in CD systems (but still a LO ROM).

The CD1 and CD2 BIOSes (FRONT-SP1 and TOP-SP1) include the "Ver 3.0 by Mr.Noric.1993/11/10 14:00" Z80 sound driver.

The CDZ BIOS includes the "Ver 3.0 by MAKOTO.04/03/10 to SK" driver.

The NeoGeo CD (not CDZ) BIOS contains credits, organized to be displayed on the fix layer (how can this be seen on screen ?):

CREDITS SOFTWARE NORIYUKI HIGASHI HARDWARE MOTOO YOKOYAMA TOSHIYA YAHARA GRAPHICS OTIAI SPECIAL JON   GUSO THANKS  CURRY SHIMIZU SNK ALL STAFF

Noriyuki Higashi = "Mr.Noric"

Toshiya Yahara is cited as the inventor of the NeoGeo Pocket power supply system in a SNK patent.

Graphic visualisation of a CDZ BIOS dump, with separated data blocks:

UniBIOS
Hacked MVS BIOS with various added functionalities such as cheats, CRC calculation, jukebox, error handling. See Universe BIOS.

Neopen BIOS
Opensource AES/MVS BIOS in development. See Neopen BIOS.