Counting test EPROM LED flashes

The PIA LED lighting at switch-on counts as flash one, not the first time it goes dark. A completed flash means that chip passed. So an LED that lights and never goes out stopped on flash 1 (the EPROM at 5C); one that goes out four times and stays lit on the fifth points at 11D. The sequence is quick, so watch closely.

Systems

• Data East CPU Version 1/2
• Data East CPU Version 3
• Data East/Sega CPU Version 3b

Related tips

• Test program does not run at all
• CPU EPROM jumpers J4 and J5
• Two PIA exceptions when using the PIA test EPROM
• Replacement CPU board won't boot with the old processor: socket contact
• CPU jumpers J4 and J5 set the EPROM size at 5C
• Running the Data East test EPROM
• Checking PIA outputs with Leon's test EPROM
• Data East CPU diagnostic test EPROM

Source: Repairing DataEast 1987 (Laser War) to Sega 1995 (Batman Forever), Part Two, Clay Harrell (pinrepair.com)