NGCD debug BIOS
The project is discontinued but the BIOS is fully functional and this page will remain.
Contents
This is basically the equivalent of the Unibios for the NeoGeo CD systems.
- Software controlled region switching
- Setting of the debug DIP and developer mode
- Setting of the system type to "home" or "MVS"
- Setting up the soft DIP just as they are on the MVS
- Cheat engine for PAR style cheats
- Robust power on self test for diagnosing faults
- Exception handling for diagnosing software/hardware faults
- Miscellaneous debugging stuff
All CD systems are supported. Each system requires a unique BIOS that is supplied in the ZIP file below.
Download
See this thread for a product that allows for simple installation in both Z and top loading models. Front loading models have a DIP BIOS so it would be similar to installing a home system Unibios. The BIOS is a 27C400 (4Mbit), not the 27C1024 (1Mbit) used in cartridge systems. They have no common pinout.
Power on
Power on with button 'A' held to access a new hardware test much like an MVS would do when powered on. This method of testing relies on very few components to be functioning in order to run a complete test and is recommended if your system starts resetting, glitching, throwing exceptions etc. Stock BIOS chips do not offer any sort of self-testing for the user.
Power on with button 'B' held to access an I/O test. Controller tests, video and audio tests are available.
Initial load
Provided the option is enabled, you will see the main menu after the game does its initial load. Any settings can be applied before the actual game begins and the same menu can be accessed at any time during gameplay.
Gameplay
Hold START + SELECT during gameplay to access the main menu at any time. You can resume the game by pressing start in any page.
Saving and loading settings
The 'SAVE' option in the menu saves some currently selected settings in your systems backup RAM. These settings apply to the current game ONLY. During the initial load, the BIOS will automatically load any settings you have previously saved for the current game. The options saved are listed here.
- System type
- System region
- Debug settings
- Game soft DIP
- Currently selected cheats
A seperate entry is made in your backup RAM for each game you save settings with. When viewing card data, you will see "(game name here) DBG" for each game you save data. The smallest possible size for a save file is used to prevent too much space from being eaten by multiple games.
The following bugs are already known:
- Many games will reset instantly when starting in MVS mode. This fix must be done for every game so it will take a while to make all games compatible
- Debug dips do not seem to have any effect on most games
The hardware selftest provides testing for many components in the CD system, which is more than what can be tested in a cartridge system thanks to the RAM based memories.