Codex Gamicus

SG-1000 Mark III
Basic Information
SG-1000 Mark II
Mega Drive
Family Computer
Technical Information
Master System
Japan Japanese Release
SG-1000 Mark III
October 201985
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The SG-1000 Mark III (also known as the SEGA Mark III) was released in Japan on October 20, 1985 at a price of ¥15,000 as a competitor to Nintendo's Family Computer.

Games for the console came in two formats; ROM cartridges and SEGA Game Cards. The cards held only 256 kilobits of data (cartridges held at least 4 times that amount, e.g. the early "mega cartridge" games with 1 Mbit / 128 kbit), but were cheaper to manufacture and sold for less than the carts did. The console also featured games built into the system BIOS that played whenever a cart or card was not inserted; the different models of the console each featured different built-in titles. The Mark III was also backwards compatible with SG-1000 software.

In 1986 and 1987, a redesigned version of the console, now branded as the Master System, was released in North America, Europe, Brazil and South Korea, and featured the addition of a built-in Yamaha YM2413 FM sound chip, a rapid fire unit and 3-D glasses; all of these had been separate accessories for the SG-1000 Mark III.

Despite a strong start, selling 1 million units in its first year on sale in Japan,[1] neither the Mark III nor its Master System variant ever posed a serious challenge to Nintendo's near-total domination of the Japanese console market.

The last licensed title in Japan was Bomber Raid, released by SEGA on February 4, 1989.

Technical details[]

The SG-1000 Mark III was built similarly to the SG-1000 Mark II, with the addition of improved video hardware and an increased amount of RAM.

The system was backwards compatible with earlier SG-1000 titles. As well as the standard cartridge slot, it had a built-in slot, formerly known as expansion slot for SEGA Game Cards, which were physically identical to the cards for the SG-1000 "Card Catcher" add-on. While in Japan there were many titles in this format published for both the SG-1000 and Mark III, only a few were published in the West.

Master System game cartridges released outside Japan had a different shape and pin configuration from the Japanese SG-1000 Mark III cartridges. This may be seen as a form of regional lockout.


See also[]


Technical Specifications
Media SG-1000 Mark III Cartridge, SEGA Card
Input Cartridge Input, Game Card Input, Power Switch, Pause Button, 2 x SG-1000 Mark III Controllers
Output A/V Output, RF Output