Sega G80

From Sega Retro

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Sega G80
Manufacturer: Sega
Release Date RRP Code
Arcade (G80)
JP
¥? ?
Arcade (G80)
US
$? ?
Arcade (G80)
DE
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The Sega G80 is an arcade system produced by Sega in 1981. It can be considered a successor to the Sega VIC Dual system, and was Sega's arcade platform of choice before the release of the Sega System 1.

The Sega G80 platform provided a basis for many reasonably successful vector-based games from the company, some of which, such as Space Fury, Tac/Scan, and, perhaps most famously, Star Trek: Strategic Operations Simulator, saw home console/computer ports.

Hardware

The G80 was designed to be a more versatile system than those seen in arcade cabinets of the past. Rather than rely on bespoke cabinet designs for each game, Sega opted for a more cost-effective "Convert-a-Game" system (as it was marketed in the US), in which games housed on CPU boards could be easily swapped by arcade operators. Announced at Visions '81[1], Sega's plan was to be able to cut install times down to 15 minutes, while also minimising production costs and tackling the poor resale value of used games[1]. As a result, "Convert-a-Paks" would cost less to buy than brand new cabinets[2].

The G80 system consists of a card cage with a 6 slot backplane that can be populated in different game configurations from a selection of 10+ different pluggable boards, allowing it to be configured as either a raster system if a raster video board is inserted, or a vector system that can display color vector graphics.

The G80 gets its name from its Z80 CPU which was coupled with a custom security chip to prevent operators from abusing the swappable system. The security chip would obfuscate the "ld (address),a" instruction (opcode 32h) differently based on the security chip installed — an early form of copy protection. The mangling algorithms are rather complicated, and differ from security chip to security chip.[3]

While Sega had high hopes for its "Convert-a-Game" system, only Sega produced games for it, and even then, releases such as Pengo did not adopt the standard. More robust arcade standards would arrive in the years which followed - the JAMMA standards are built around the same idea of swappable arcade PCBs, but do not tie developers down to specific hardware. It is mainly the input and output connectors that are standardised instead.

Space Odyssey was the first game to use this system, followed by Space Fury[1].

Technical specifications

  • Board composition: One board
  • Main CPU:[4]
  • Sega USB (Universal Sound Board)
  • Speech Board (optional)
  • Sega System 1 sound board (optional, used for Sindbad Mystery in 1983)
  • Sound chips: Sega SN76496 @ 4 MHz, Sega SN76496 @ 2 MHz
  • Horizontal: 256×224 (display), 328×262 (overscan)
  • Vertical: 224×256 (display), 262×328 (overscan)[5]
  • Raster: 14 KB (2 KB main, 8 KB video, 4 KB audio)
  • Vector: 10 KB (2 KB main, 4 KB video, 4 KB audio)
  • Monster Bash & Sindbad Mystery: 24 KB (4 KB main, 16 KB video, 4 KB audio)

List of games

Raster

Vector

References


Sega arcade boards
Originating in arcades









Console-based hardware








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PC-based hardware








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