The SG-1000 Mark III is an 8-bit video game console made by Sega. It was the original Japanese incarnation of the Sega Master System.

History

The Mark III was released in Japan on October 20, 1985 to compete with the Nintendo Family Computer, following on from the SG-1000 Mark I and SG-1000 Mark II. The Mark III was built similarly to the Mark II, with the addition of improved video hardware and an increased amount of RAM.

The system is backwards compatible with earlier SG-1000 titles. As well as the standard cartridge slot, it has a built-in slot for "Sega Cards", which are physically identical to the cards for the Sega SG-1000 "Card Catcher" add-on.

The Mark III was redesigned as the Sega Master System for release in other markets. This was mainly a cosmetic revamp; the internals of the console remained virtually the same. The redesigned console was itself released in Japan in 1987, but with the addition of a built-in Yamaha YM2413 FM sound chip (this had been an optional extra on the Mark III), and Rapid Fire Unit.

Sega Master System game cartridges released outside Japan had a different shape and pin configuration to the Japanese Master System/Mark III cartridges. This may be seen as a form of regional lockout.

Neither the Mark III nor the Japanese Sega Master System were commercially successful, due to strong competition from the Nintendo Famicom. The final Japanese game release was Bomber Raid , on February 4, 1989.

Specifications

• CPU: 8-bit 3.579545 MHz Zilog Z80
• Graphics: VDP (Video Display Processor) derived from Texas Instruments TMS9918

• Up to 32 simultaneous colors available from a palette of 64 (can also show 64 simultaneous colors using programming tricks)
• Screen resolutions 256x192 and 256x224
• 8x8 pixel characters, max 488 (due to VRAM space limitation)
• 8x8 or 8x16 pixel sprites, max 64
• Horizontal, diagonal, vertical, and partial screen scrolling

• Sound (PSG): Texas Instruments SN76489

• 4 channel mono sound
• 3 sound generators, 4 octaves each, 1 white noise generator

• Sound (FM): Yamaha YM2413

• 9 channel mono FM sound
• available as plug-in module for Mark III
• built into Japanese Master System
• supported by certain games only

• ROM: 64 Kbits (8KB)
• Main RAM: 64 Kbits (8KB)
• Video RAM: 128 Kbits (16KB)
• Game Card slot

External links

• Mark III Console Database