162/164 is a MAME figure judged on the picture, not evidence for real hardware. PrivaBIOS has run on one real board so far.
Everything in one chip
In-game menu
Settings, cheats, memory editor.
Autofire
Per game, per button.
Free play
No continue, silent demo.
Hardware tests
RAM, video, inputs, cartridge CRC.
Memory card
List, delete, format, copy.
Jukebox
Every sound of the cartridge.
Why another BIOS?
UniBIOS is the reference on the Neo Geo, and Razoola's work has served players for two decades. PrivaBIOS takes a different path: a BIOS written from scratch, GPL-3.0, with its whole source open to anyone who wants to read, fix or change it.
- Autofire as a setting: A, B, C and D one by one, at 10, 15 or 30 shots per second, remembered for each game.
- Game settings changed from the in-game menu, during play.
- Settings of a game that has never been launched: the editor shows its defaults and saves a clean entry.
- A boot screen drawn only with the board's font, nothing from the cartridge's graphics.
- No continue and silent demo for the whole cabinet.
It is a young project: a beta for MVS boards, with a growing cheat list (1,709 for 154 games), tested on one real board so far. Your reports shape what comes next.
How it was made
Coding agents wrote the code, from contracts drawn by observing the original BIOS running, copying no SNK or UniBIOS code (one incident is on record). Nobody has to take that output on trust: every function a player sees has a test scene under MAME, judged on picture or sound, and every scene is proven by planting a bug it must catch. MAME is not a board, so real-hardware reports decide the rest. The full method.
Two ways to run it
On an MVS board
- Download the image (or the byte-swapped one, on the release page, if your programmer needs it).
- Burn it on a 27C1024.
- Swap it with the BIOS chip.
- Keep the original.
In MAME
- Download the image.
- Replace
sp-s2.sp1in your romsets. - Run with
-bios euro.
Checksums are on the release page. To build the image yourself, see BUILD.md.
This is a beta. Before swapping chips, write down your board's settings and keep the original chip. Under MAME, moving from the SNK BIOS or UniBIOS 4.0 to PrivaBIOS and back left the backup RAM's game data intact, with one game and no setting changed. That was not measured on a real board, nor after changing settings here, so treat scores and settings as things you could lose.
Questions
Does it run on my board?
Tested on a real MV-2F, and on the MV-6F under MAME. Other boards are untested: tell us how it goes.
And on an AES console?
Not yet. It has an AES mode for MVS boards only.
Does autofire work in every game?
No. 89 of 164 MAME sets see it fully; games that read the joystick themselves never do.
Can I go back to my old BIOS?
Yes. Keep the original chip and swap it back.