Written by BonusKun

This is a general faq for owners of Neo*Geo home systems that have had a debug bios chip installed by either MAS Systems or Mr. J.M. Kurtz. This FAQ will not only shed some light on the functions available to those that already have the mod, but also allow non-modded system owners to make an informed judgement regarding mod purchase. This is a work-in-progress faq, and far from complete, so reader input is greatly welcomed.

The Neo*Geo debug bios chip allows one to access Neo*Geo home cart games' "hidden" or "locked out" features--features which normally are not accessible on a home cart system. For example, the player can use the new bios to boot the Neo*Geo as a U.S., Japanese, or European home system OR MVS system. To go into the Bios you would simply take controller 2, Hold Select and Hit C. If one owns a standard U.S. Neo*Geo cart system, for instance, and boots any Last Blade 2 cart, blood, finishing moves, and extra animations (deemed too violent for the U.S. market by SNK) are removed. With the debug bios, one can simply boot the game in a country or system mode that removes these restrictions (I.E. Japanese home setting). The MVS system setting offers the exact changes the arcade version game would provide, for better or for worse--training modes can be eschewed for unlimited credits, and sometimes the occasional hidden character is locked/unlocked. This can also have a similar effect to a country mode change regarding censorship.

(Note of interest: The Neo*Geo censorship predates back to Samurai Shodown 1 U.S. home cart, in which blood was censored. This angered many Neo*Geo gamers at the time, especially when the game was considered a staple of SNK's success. The concept still angers Neo*Geo players today.)

The chip also allows you to change the basic variables of some games (like a GameShark of sorts)--a good aid for those frustrated with difficult restrictions on lives and continues. In the Metal Slug series, for example, you can adjust variables to give yourself 99 lives, invincibility or even unlimited ammo.

These kinds of changes are done through the Dip Settings Menu, which is set up in 2 Rows, like this:

0 0 0 0 0 0 0 0
| | | | | | | |
1 2 3 4 5 6 7 8 
0 0 0 0 0 0 0 0
| | | | | | | |
1 2 3 4 5 6 7 8

Usually these are set to zero (off), although I've seen a few games which have some dips defaulted on. An example of dip switch use is selecting Zero as a playable character in The King of Fighters 2000. At the player select screen, one would turn on Dip 1-3, and then highlighting Kula Diamond, holding start, and pressing down would highlight Zero. As in this example, DIP usage is often accompanied with in-game codes.

There are many more DIP combinations for different games, to be sure, but I have decided to keep the DIP code library separate from the basic FAQ. Keep checking this page often for new DIP codes for various games.

Thanks to Shawn for hosting this FAQ, and to Ven for his aid. If you have any questions, contact me at and I'll try to help any way I can.


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