FD1094 and FD1089 suicide battery
Some System 16, System 18 and System 24 boards by Sega have custom cpus labeled FD1094 or FD1089. These are 68000 processor cores with a battery and encryption keys which are used to decrypt the game at run-time. Unfortunately these batteries eventually die out and the game is rendered useless.
There are two ways of preventing this from happening. You can replace the battery inside of these - and keep doing so every 5 years or so - in order to keep them as original as possible; or you can buy/build a kit to replace the encrypted ROMs with unencrypted ones and change the FD processor for a standard 68000 one.
Please refer to the external links section for information on these methods.
- Sega Resurrection A site that sells kits to revive dead Sega boards
- The Dead Battery Society Site with information on suicide arcade games
- JAMMA Nation X has a tutorial to change an FD processor battery, check under Other->Misc.
- Charles MacDonald FD1094 Game Conversion Information on how to decrypt these games by yourself