From Sega Retro
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
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.
List of Games (Raster Version)
List of Games (Vector Version)