The four System 11 CPU generations and why they differ
There are four CPU generations: System 11, 11A, 11B and 11C. The changes are mostly in sound: each generation moved more of the sound circuitry off the CPU board, and on 11C nearly all of it is on the separate sound board. Know which generation you have before ordering parts or boards, because components and boards changed with each one.
Systems
Related tips
- Which System 11 CPU boards fit which games
- How to tell a System 11C CPU from an 11B
- Setting up Leon's System 11 CPU test EPROM
- Bench-check the System 11 CPU switch matrix circuit
- System 11 CPU board part numbers and spotting features
- System 11A-11C CPU LEDs: normal state
- Early System 11 CPU in a later game gives meaningless LED codes
- System 11A jumpers W16 and W17 depend on the CPU chip brand
Source: Repairing Williams System 11 Pinball 1986 to 1990, Deel 1, Clay Harrell (pinrepair.com)