Address lines are good but the test program still does not reach the PIAs.

PIAs or the EPROM are never selected

Cause: A fault in the address decoding (select) chips at 8D, 8E, 7E and 7C.

Checks

• With the EPROM removed and the CPU free-running, pin 23 of each PIA should read about 4 V.
• Pin 20 of the EPROM socket at 5C should also show its select signal.
• If missing, trace back through 8D (PIA addresses 3400, 3000, 2C00, 2800, 2400) and 8E (address 2200) toward address lines A14 and A15.

Fix

• Replace the failed decoder chip.

Systems

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

Related tips

• Two PIA exceptions when using the PIA test EPROM
• Test program does not run at all
• Checking PIA outputs with Leon's test EPROM
• One PIA output does not toggle under the test EPROM
• Coil passes every test but still will not work in play
• Battery voltage at the RAM but memory still lost
• CPU EPROM jumpers J4 and J5
• CPU board PIA positions and jobs

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