System 6 CPU board changes and ROM layout
System 6 moved to the 6802/6808 CPU (no separate clock chip) and added a memory protect circuit. Game code is three 512-byte ROMs at IC21, IC22 and IC26 or one 2716/2316 at IC14, with the flipper ROMs at IC17/IC20. The battery holder moved to the bottom right near the test switches.
Systems
Related tips
- Identifying a System 3 to 7 CPU board
- What changed on the System 6A CPU board
- System 6 CPU board test points
- Which System 3 to 7 games use which flipper ROM system
- System 6 CPU board jumpers J1 to J6
- A System 7 CPU board can run any System 3 to 7 game
- Run a System 6/7 CPU board on +5 V only
- Which CPU boards can run which system firmware
Source: Repairing Williams System 3 to System 7 Pinball 1977 to 1984, Part One, Clay Harrell (pinrepair.com)