Sega G80

The Sega G80 is an arcade system produced by Sega in 1981. There are two versions of the G80 — one that displays raster graphics and one that displays vector graphics.

G80 games use swappable CPU boards for games. An interesting feature of the G80 — and where it gets its name from — is that the CPU, a modified Z80 running at 3.86712MHz, is stored on the cart. The G80 is identical to the Z80, except the

ld (address),a

instruction (opcode 32h) was modified to mangle the address written to — a form of copy protection. The mangling system is rather complicated, and differed from game to game.

Specifications

• Main CPU: see above
• Sound: some combination of the following (depending on the game)
  • Pure discrete sound
  • Speech board, with Intel 8035 + GI SP0250 speech synthesis chip
  • USB board, with Intel 8035 and hacked up tone generation with timers and dacs for volume.
• Video resolution: 256 x 224 (raster version)
• Board composition: one board

List of Games (Raster Version)

• 005 (1981)
• Astro Blaster (1981)
• Monster Bash (1982)
• Pig Newton (1983)
• Sindbad Mystery (1983)
• Space Odyssey (1981)

List of Games (Vector Version)

• Battle Star (1982)
• Eliminator (1981)
• Eliminator 4 Player (1981)
• Space Fury (1981)
• Star Trek: Strategic Operations Simulator (1982)
• Tac/Scan (1982)
• Zektor (1982)