CPU jumpers J4 and J5 set the EPROM size at 5C

Secret Service to Batman shipped with a 27256 at 5C (and a 27128 or 27256 at 5B), with J4 fitted and J5 removed. From Star Trek 25th Anniversary through Batman Forever the boards use a single 27512 at 5C with J5 fitted and J4 removed. Set J5 in and J4 out to run any single 27512, including the test EPROM.

Systems

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

Related tips

• CPU EPROM jumpers J4 and J5
• Other CPU jumpers and what they set
• Full CPU jumper settings by board version
• Leon's Data East CPU test EPROM
• Bench-testing a CPU board on +5 V
• CPU boards are only downward compatible
• Two PIA exceptions when using the PIA test EPROM
• Program runs but the PIAs never respond

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