What Do the Masked ROMs Chip Numbers Mean?
If the game in question uses original black masked ROMs, there are numbers on the ROMs that denote information about the chip. This information is can be seen by clicking ballyro2.htm, where the ROM numbers are sort numerically. Another page located at ballyrom.htm shows the same information, but sorted by game name. Also shown are the original jumper settings. In addition, the chart at roms.htm shows the Bally ROM part numbers and checksums. Note the higher -xx number means a later revision. In the case of the U6 chips, that revision is important, as generally a game can not be run with the “wrong” U6 part. But for the U1/U2 chips, it usually means a later version of the same game (and all the chips must be of the “correct” revision to match the others, though there’s not always a good way to know what that is). As an example, Lost World uses “720-28” for U6. But then the other chips should all be “729-xx”, with the latest revision being “729-33” at U1, and “729-48” at U2. If the game
