The dot matrix display has its own computer

The 6809 on the main CPU board runs the switches, lamps and coils. A separate processor on a board behind the display (a Z80, 68B09 or 68000 depending on display size) draws the animations. The main CPU sends it numbered commands over a ribbon cable.

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
• Dot matrix controller CPUs by display size
• Dot matrix controller boards
• Voltages a small or medium dot matrix display needs
• Checklist for a dead small or medium dot matrix display
• 192x64 display games have their own display supply fuse F3

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