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The History of Video Games #23: The SEGA MK III

Updated: Jan 28, 2022

Sega MK III console

Welcome back, everyone. In the last article, we investigated SEGA’s first consoles, the SG-1000 and SG-1000 MK II. Now we will investigate the successor to these Japanese consoles, the imaginatively named SEGA Mark III. Let's dive in…

Full disclosure, I have no hands on experience with the MK III, so all info here is from 2nd hand sources. If there are any inaccuracies, please let me know.

Form Factor

Externally, the Sega MK III closely resembles the SG 1000 MK II, but features several enhancements.

  • The MK III features an integral card slot, allowing the MK III to play card-based games without the need for the Card Catcher peripheral.

  • The two DE-9 controller ports were moved to the front of the unit for easier access.

  • An expansion port on the left side of the console. This would go on to be used with the FM Sound Unit for superior sound effects and music.

  • In addition to the standard RF TV-Out port, the SG MK III sported an 8-pin A/V port, allowing for a sharper on-screen image.

Internal Hardware

Where the MK III really excelled over the SG 1000 II was in its internal hardware. In addition to more RAM, the MK III sported a new and improved Video Display Processor, which could create superior graphics, with smoother scrolling and approximately twice the number of on-screen colours. In terms of graphics, the MK III was superior to Nintendo’s Famicom.

Sega  MK III colour palette by K
Sega MK III colour palette by Kaztah

AV Port

The AV port allowed for sharper images to be displayed on compatible screens, thus enhancing the MK III’s visual fidelity further.

(I haven't been able to find any images or videos showing this, sorry. If you have any, or know where some can be obtained, please let me know and I'll include them.)

FM Sound Unit

The optional FM Sound Unit, which was released only in Japan for the MK3, added 9 additional mono channels for enhanced sound, although sadly not all games supported it.

Compared to the Famicom, the sound of the MK III was inferior. However, with the boost it gained from the FM Sound Unit its audio became superior to the Nintendo console. Nintendo would regain the upper hand with the release of the Famicom Disc System, which featured sound effects and music capabilities superior to them all.

Sega Master System FM Sound Comparison

Physical Media

The MK III used the same physical media formats as the SG-1000/II and was backwards compatible with SG-1000/II games. Technically, games could have used tapes as well due to the MK III’s compatibility with the Data Recorder SR-1000, although few, if any, MK III games utilised this format.


The controllers received another upgrade in the form of the SJ-152. The D-Pad’s shape was changed from the circle used on the SJ-151 to a rounded square. At least some versions retained the removable thumbstick. As with earlier Sega joypads, the SJ-152s could be stored attached to the side of the MK III console. Unfortunately, this required the wire to extend from the side of the controller, which was not ergonomically ideal.

Sega SJ-152 joypad
Sega SJ-152 joypad

The MK III also supported the NDP-200 Paddle Controller, which sadly never saw a release outside of Japan. Due to this, games that required the paddle controller were also Japanese exclusives.

NDP-200 Paddle Controller
NDP-200 Paddle Controller


The MK III’s launch titles included Hang-On and Teddy Boy Blues, both released on the budget-conscious SEGA MY card format. It would take approximately eight months for cartridge production to begin anew. As a result, Fantasy Zone was the first MK III game released on cartridge.

Since the MK III would go on to spawn the SEGA MasterSystem, many MasterSystem games were released on the MK III as well. Note that MasterSystem and MK III carts are not interchangeable due to their different sizes – they simply will not fit in each other’s slots.

Approximately 80 games were released for the MK III. This included several Japanese exclusives that were never officially released in the West. The video below shows a few of these.

Japanese Exclusive Master System / MK III Games

Sega published every Mark III game internally except for two, Argos no Juujiken and Solomon no Kagi: Oujo Rihita no Namida by Salio. Official SEGA support for the MK III lasted until February 1989, ending with the release of Bomber Raid.

Bomber Raid Master System / MK III with FM Sound

The last officially supported game for the Sega MK III

Video by World of Longplays


The peripherals released for the SG 1000/II were compatible with the MK III. An additional addon, the Telecon Pack was released in Japan. The Telecon pack enabled the MK III to connect to a compatible TV wirelessly, however, results were mixed.

Telecon Pack
Allegedly this rarely worked as well it was hoped


The MK III was released in Japan in October 1985, with South Korean and Taiwanese releases approximately ten years later.

Reception and Sales

Despite the MK III’s impressive technical specifications and library of high-quality games, SEGA was unable to topple Nintendo’s Famicom from its dominant position in the Japanese video game console market. By 1989, the Sega Mark III had sold over 1.7 million units in Japan, a respectable figure, but far behind the approximately 19.35 million Japanese Famicoms sold.


Although SEGA saw only limited success in Japan with the MK III, its export-orientated cousin, the SEGA MasterSystem, saw far greater success globally, especially in the markets that the NES had failed to gain traction, such as the UK, Europe and South America. And this will be the topic of the next article. See you all there.


This article would not have been possible without the on-line content I used for research, so I would like to say a big thank you to the Wikipedians who created and updated the wiki pages, the fine folks behind sega retro, kaztah, and the Youtubers d34dm34t retro, Retro Recollections and Kelsey Lewin.

Iain is a 40+ author and gamer from England, who started his gaming journey on the Atari 2600 36 years ago. His specialities include obscure cult classics, retro games, mods and fan remakes. He hates all sports games and is allergic to online multiplayer. Since he is British, his body is about 60% tea. He can be reached via Twitter at, and contacted via email at

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