System 80 and 80A CPU boards swap only with the matching U2/U3
U2 and U3 hold the game-rules code and differ between System 80 and System 80A, so a board from one swaps into the other only after U2/U3 are changed. They are mask ROMs, so an EPROM needs an adapter board or board modification. Note the 80A board has U2/U3 socketed; the earlier boards do not.
Systems
Related tips
- Which System 80 CPU board goes with which games
- Swapping CPU boards between System 80, 80A and 80B
- System 80 CPU board main chips
- Reading the System 80 CPU DIP switches
- U2/U3 rules ROMs decide which system a CPU board runs
- System 80 CPU board revisions D102, D107 and D20869
- System 80 CPU board passive parts and diodes, board-wide
- 6532 RIOT port pins on the System 80 CPU board
Source: Repairing & Upgrading Gottlieb System 80 Pinballs from 1980 to 1989, Part One, Clay Harrell (pinrepair.com)