System ROM: Difference between revisions

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[[File:biosmenus.png|thumb|(Enlarge) Configuration and book keeping menus in the SP-2 MVS BIOS]]
[[File:biosmenus.png|thumb|(Enlarge) Configuration and book keeping menus in the SP-2 MVS BIOS]]


The system ROM (often called BIOS) is a ROM containing code for the [[boot process|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 [[CD systems|NeoGeo CD]] system ROM also contains graphics, sound, and {{Chipname|Z80}} code.
The system ROM (often called BIOS) is a ROM containing code for the [[boot process|68k startup program]], [[system ROM tables|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 [[CD systems|NeoGeo CD]] system ROM also contains graphics, sound, and {{Chipname|Z80}} code.


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

Revision as of 05:16, 6 April 2016

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

The system ROM (often called BIOS) is a ROM containing code for the 68k startup program, 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 Z80 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 NEO-EP0.

MVS

Toshiba SP-S2 on a 1FZS MVS slot.

Size: 128KiB. Called SP-S2, "SP-E"... Different names according to nationality.

Graphic visualisation of sp-s2.bin:

binviewsp2.png

CD/CDZ

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.

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

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 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:
File:Cdzbiosgfx.png

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.