The display shows text like "Command 24" or behaves oddly in place of an animation.

Display shows "Command" numbers instead of animations

Cause: The CPU game ROM and the display ROM are different versions, so the CPU asks for an animation the display code does not have.

Checks

• Read the version of the CPU ROM and of the display ROM.

Fix

• Fit matching versions of both (for example 2.x in both).

Systems

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

Related tips

• Display not working: check +5 V at the controller first
• Dot matrix display goes blank after a few minutes
• Dot matrix controller boards and processors by game
• Game will not boot: GI on, little else happens
• Random glitches in play (DMD freezes, odd awards): reseat the ribbon cables
• The Simpsons: CPU and display EPROM types and latest versions
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• Batman: CPU and display EPROM types and latest versions

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