If anybody is interested, here are some general textfiles about Vectrex.

• How to make Vectrex cartridges.
  
• Internal information on the Vectrex.
  
• interfac.txt - Part 1 of making a simpler cartridge interface.
  
• interfa2.txt - Part 2 of making a simpler cartridge interface.
  
• Pinouts for the Vectrex.
  
• Instructions for the Vectrex music program, "PLAY.PAS".