System ROM



The system ROM (often called BIOS) is a ROM containing code for the 68k startup program, some lookup tables, 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.

Official system ROMs have their nationality set by the byte at address $000401 (0=Japan, 1=US, 2=Euro), and their type set by the byte at $000400 (0=AES, $80=MVS).

=Hashes=

Copied from MAME's source code.

=Use=

The system ROM contents are simply mapped at $C00000 and available at all times.

See:
 * System ROM calls
 * Hardware test
 * System ROM tables

=Home system=

Size: 128KiB. Named.

=MVS=

Size: 128KiB. Often named "SP" for System Program. Many different versions.

=CD/CDZ=





Size: 512KiB.


 * FRONT-SP1 (Front loader)
 * TOP-SP1 (Top loader using )
 * TOP-SP2 (Top loader using )
 * TOP-SPD (CDZ)

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

The CD1 and CD2 system ROMs contain credits, organized to be displayed on the fix layer (how can this be seen ?):

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.
 * Jo(h)n Guso is credited as a programmer in several games.

Sound drivers
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.

=UniBIOS=

Hacked MVS system ROM with various added functionalities such as cheats, debug DIPs settings, region and system switch, CRC checking, a jukebox, error handling. See Universe BIOS.

=Neopen BIOS=

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