System ROM



The system ROM (often called BIOS) is a ROM containing code for the 68k startup program and various generic functions which can or must be used by games. They are present in all hardware types in various versions. The NeoGeo CD system ROM also contains graphics, sound, and code.

The official system ROMs have their nationality set by the byte at address $000401 (0=Japan, 1=US, 2=Euro).

The type is set by the byte at $000400 (0=AES, $80=MVS).

=Included lookup tables=


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

To do: Which games use them ?

=AES=

Size: 128KiB. Called.



=MVS=



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

Graphic visualisation of sp-s2.bin:



=CD/CDZ=



Size: 512KiB.


 * FRONT-SP1 (Front loader)
 * TOP-SP1 (Top loader, LC8953)
 * TOP-SP2 (Top loader, LC98000)
 * TOP-SPD (CDZ)

Contains and  programs, PCM sound, and graphics which are copied to the corresponding DRAMs at boot time. There is no or  ROMs in CD systems (but still a  ROM).

The CD1 and CD2 system ROMs (FRONT-SP1 and TOP-SP1/SP2) include the "Ver 3.0 by Mr.Noric.1993/11/10 14:00" Z80 sound driver.

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

The CD1 and CD2 system ROMs contain 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 is the infamous "Mr.Noric".

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

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

=UniBIOS=

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

=Neopen BIOS=

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