CPU chips Leon's test code does not need
Leon's code still boots with these parts pulled. System 3/4: all ROMs except the test EPROM (IC14, IC20, IC21, IC22, IC26), both 6810 RAMs (IC13, IC16), the 5101 (IC19), the 74154 (IC6) and the 7408 (IC12). System 7: the ROMs at IC14, IC20 and IC26, the 2114 RAMs (IC13, IC16), the 5101 (IC19), the sound PIA, plus the 74LS02 (IC5), 74154 (IC6), 4071 (IC10), 74LS10 (IC11), 7408 (IC12) and 4020 (IC25).
Systems
Related tips
- Test the CPU board PIA IC18 with Leon's code
- Chips a System 7 CPU board needs to run the Williams test ROM
- Obsolete chips on System 3 to 7 CPU boards
- Leon code running but LEDs dark: bad CPU PIA IC18
- A PIA output fails Leon's test but the PIA is good
- CPU chip types: 6800 on System 3/4, 6802 or 6808 on System 6/7
- CPU locked: check the EPROM chip select
- Replacing the 6802 CPU with a 6808
Source: Repairing Williams System 3 to System 7 Pinball 1977 to 1984, Part Two, Clay Harrell (pinrepair.com)