System 6 CPU board jumpers J1 to J6
J3/J4 (right of IC15) set the addressing of IC21/IC22/IC26: J3 in and J4 out with EPROMs and no PROMs; J3 out and J4 in with original PROMs (Firepower factory setting). J1 (lower left of IC1) is normally in, with R4 out. J2 (right of IC30) is normally out. J5 (right of IC11) is normally in and enables memory protection; removing it turns protection off. J6 (right of IC11) is normally in; removing it halves the interrupt period from 1 ms to 0.5 ms.
Systems
Related tips
- Identifying a System 3 to 7 CPU board
- What changed on the System 6A CPU board
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- A System 7 CPU board can run any System 3 to 7 game
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Source: Repairing Williams System 3 to System 7 Pinball 1977 to 1984, Part Two, Clay Harrell (pinrepair.com)