System ROM

(Enlarge) Configuration and book keeping menus in the SP-2 MVS BIOS

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).

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:

binviewsp2.png

CD/CDZ BIOS

File:Cd2 bios.jpg

TOP-SP1 BIOS ROM on a CDM3-2 board.

File:Brd spj.jpg

SPJ Japanese BIOS on a ROM-only arcade board. Picture courtesy of [MVS-Scans].

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

Graphic visualisation of a CDZ BIOS dump, with separated data blocks:
File:Cdzbiosgfx.png

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.