System ROM

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

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

MVS BIOS
Size: 128KiB. Called "SP-S2". Different names according to nationality.

Holds functions for coins, calendar and player starts.

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: