System ROM

BIOSes (officially called "SYSTEM ROM") are ROMs containing various generic functions and the startup program for NeoGeo systems. They are present in all hardware types.

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).



Cart BIOSes have their nationality byte at address $401 ($C00401).

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:



UniBIOS
See Universe BIOS.

CD/CDZ BIOS




Size: 512KiB.

Chip that contains Z80 and 68k programs, PCM sound, and graphics which are copied to the corresponding DRAMs at boot time. The BIOS on CD systems also contains graphics and sounds. There is no SFIX or SM1 ROMs on cart systems.

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

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