Sega G80
From Sega Retro
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| Sega G80 | |||||
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| Manufacturer: Sega | |||||
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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 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. The G80 system consisted of a card cage with a 6 slot backplane that could be populated in different game configurations from a selection of 10+ different pluggable boards, allowing it to be configured it as either a raster system if a raster video board was inserted, or a vector system that could 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.[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.
Technical specifications
- Board composition: One board
- Main CPU:[2]
- Sound boards:[2][1]
- Sega USB (Universal Sound Board)
- MCU: Intel i8035 @ 3.12 MHz (8-bit instructions, 3.12 MIPS, 1 instruction per cycle)
- Sound chip: Sega Melody Generator (programmable sound generator)
- Speech Board (optional)
- MCU: Intel i8035/i8039 @ 3.12 MHz (8-bit instructions, 3.12 MIPS)
- Speech synthesizer: General Instrument SP0250 (linear predictive coding)
- Sega System 1 sound board (optional, used for Sindbad Mystery in 1983)
- Sound chips: Sega SN76496 @ 4 MHz, Sega SN76496 @ 2 MHz
- Sega USB (Universal Sound Board)
- Raster graphics board: Sega Video I[1]
- Raster display controller: Sega Raster Display Controller @ 15.468 MHz
- Video resolution:
- Horizontal: 256×224 (display), 328×262 (overscan)
- Vertical: 224×256 (display), 262×328 (overscan)[3]
- Color palette table: 256 (8-bit RGB PROM)
- Colors on screen: 64 to 128 (palette RAM)
- Tilemap planes: 2 layers, horizontal and vertical scrolling,[3] 8×8 tiles, 4 colors per tile
- Sprite capabilities: 28 to 32 sprites per scanline, 224 to 256 sprite pixels/texels per scanline, 4 colors per sprite, 8×8 to 16×16 sizes[2]
- Vector display controller: Sega Display Controller[4]
- Color depth: 64 (6-bit RGB)[5]
- RAM:[2][1]
List of games
Raster
- 005 (1981)
- Astro Blaster (1981)
- Space Odyssey (1981)
- Monster Bash (1982)
- Pig Newton (1983)
- Sindbad Mystery (1983)
Vector
- Space Fury (1981)
- Eliminator (1981)
- Battle Star (1982)
- Star Trek: Strategic Operations Simulator (1982)
- Tac/Scan (1982)
- Zektor (1982)
References
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