Sega Genesis

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Sega Genesis 2

The Sega Genesis is a 16-bit video game console released by Sega in North America in 1989. Outside of North America the console is known as the Sega Mega Drive. It succeeded the 8-bit Sega Master System and was one of the main contenders in the console wars of the early 1990s. The Genesis launched the 16-bit era of console gaming, although, in the end, it was outsold by rival Nintendo's SNES console worldwide.

The system was internally compatible with the Sega Master System and a converter was available, called the Power Base Converter. It plugs into the cartridge port and features cartridge slots for Sega Master System cartridges. All Master System accessories, including the light gun and 3D glasses, can be used for this converter.



16-bit home computers like the Commodore Amiga and the Atari ST, as well as 16-bit arcade machines, were outpacing the 8-bit videogame consoles of the mid-to-late-1980s. Nintendo at the time had 95% of the North American market, and 92% of Japan's. Sega's Master System was failing in North America and Japan, and so Sega decided to make a new console.

Since the System 16 arcade games that Sega was making were very popular, Hayao Nakayama, Sega's CEO at the time, decided to make their new home system a 16-bit one. The final design worked great and fit in well with Sega's three new arcade boards; the Mega-Tech, Mega Play, and the System C. Any arcade game made for these systems could easily, and thus rapidly, be made to work on the new console (a process known as porting).

The first name Sega considered using for its 16-bit machine was "MK-1601", but they later decided to use Sega Mega Drive. The name was designed to imply superiority, speed, and power. However, "Mega Drive" was trademarked in the United States, so Sega chose the name Genesis for that region, a name meant to mark the beginning of a new age in videogames.


In 1987, Sega announced their North American release date and stated that their own console was the first true 16-bit console (a dig at NEC's TurboGrafx 16, which was being marketed as 16-bit).

The Genesis was released in the United States in January 9, 1989 in New York City and Los Angeles only. It sold for around $200 at launch and was to become Sega's most successful console. It was released in the rest of North America on September 15 with a reduced price of $190.

The Genesis initially competed against the 8-bit Nintendo Entertainment System, but although it had superior graphics and sound, it had a hard time overcoming Nintendo's ubiquitous presence in the consumer's home. Sega of America competed by focusing on a slightly older user base, with such titles as Altered Beast and the Phantasy Star series. The TurboGrafx 16, which had been released six months earlier, had been poorly marketed in North America, so it wasn't a threat in that market.

Some felt there were too many arcade ports in the Genesis's library, and that there wasn't a "killer app", but third party companies such as Electronic Arts (The Immortal), kept the console alive.

Eventually, the Genesis' main competition became Nintendo's 16-bit Super Nintendo, over which it had a head start in terms of user base and number of games. The Genesis continued to hold on to a healthy fan base composed significantly of RPG fans and sports games fans, and the release of Sonic the Hedgehog in 1991 began to threaten Nintendo's up-to-then stranglehold on the number one console position in the USA. Sonic was released to replace former mascot Alex Kidd, and to provide the "killer app" that Sega needed. This sparked what was arguably the greatest console war in North American video gaming history, at least up until that point. By 1992, Sega had a 55% market share in the North American video game market.

The release of the highly-anticipated Sonic the Hedgehog 2, coinciding with an aggressive ad campaign that took shots at Nintendo, propelled the Genesis into its heyday, outselling the Super Nintendo for the first time since the SNES's release.

Also in 1992, Sega redesigned the console and released the Sega Genesis 2, which reduced cost and size by consolidating chips, and integrated stronger region encoding (which broke compatibility with some older games). The original console itself went through innumerable revisions -- unknown to most users, the very first consoles had trouble playing a few of the newer games. A new version of the Sega CD, the Sega CD 2, was made to accommodate this.

The Sega CD and Sega Genesis 32X (Sega Super 32X in Japan and Sega Mega 32X in Europe) were peripherals which provided technological enhancements to the Genesis, allowing it to play CD-based and 32-bit games, respectively. However, both were disappointments because of poor third party support.

Because of the failures of the Sega CD and 32X, the lack of advertising, and the disputes between Sega of America and Sega of Japan, things were grim by 1994. The Genesis version of Mortal Kombat outsold the SNES version four to one despite being a technically inferior port, because the Sega version had uncensored violence, unlike the Nintendo counterpart. However, people became worried over the level of violence in this and other Sega videogames. Sega introduced the Videogames Rating Council, or VRC, to combat this.

Market share dropped from 65% to 35% within the course of 1994. Announcements of newer, more powerful consoles, such as the Sega Saturn, Sony PlayStation, and Nintendo's "Project Reality" (codename for the N64) signaled that the 16-bit era was drawing to a close, with a corresponding drop in interest in the Genesis (see Video game market).

Sega also partnered with Time Warner in the US to offer a subscription-based service called the Sega Channel. The Sega Channel allowed users to download a set number of new video games a month.

In 1995, a portable version of the system called the Sega Nomad was released.

In 1996, Sega dropped support of the Genesis in favor of the Sega Saturn.

Sega considered a Game Gear Converter, tentatively named the Mega Game Gear, but it was never produced.

Majesco's Genesis 3 with a 6 button arcade gamepad and Comix Zone in the cartridge slot
In 1997, Majesco announced that they wanted to make a budget version of the Genesis. In 1998, Majesco released the "Sega Genesis 3" for $50, in North America only.

There were also a number of Genesis clones (see below).
In recent years, the Genesis/Megadrive has had something of a revival, lead largely by the grey market trade in both unlicensed cartridges (for instance, the biblically-themed output of Wisdom Tree) and dumped ROMs, which are played through emulators such as Gens. There is also a trend towards home programming of the Genesis, using the PC-based SGCC.

Versions of the Sega Genesis

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Two versions of the Genesis controller. 3-button (top) and 6-button (bottom) pads
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European (left) and American (right) boxes
  • Sega Genesis 1
    • New name (since "Mega Drive" was trademarked in the United States)
    • English-language settings
    • Headphone jack
    • AUX port
    • Supports Sega CD and Sega 32X
    • Cartridge lock removed
    • Larger "16-Bit" logo and a large "Genesis" logo is printed in front of cartridge port
    • Reset button and start button on Joypad are now white
    • There are at least two revisions of the Genesis 1:
      • A version with a white connector for a modem (?) next to the power plug
      • One without this plug
  • Sega Genesis 2
    • New squared shape
    • No headphone jack
    • A/V port changed to one custom multi output for picture and sound (older model only emitted mono sound, as stereo came through the headphone jack)
    • Push button power switch
  • Sega Genesis 3 by Majesco
  • X'Eye (named Wondermega for Japanese release) - A combined Mega Drive and Mega-CD by JVC
    • Improved sound capabilities
    • MIDI connections
    • Two microphone inputs
    • S-Video output (Wondermega only)
    • Packaged with a CD called Game Garden that had Flicky a (quiz game) and Pyramid (a puzzle game). The CD is compatible with CDG (CD and Graphics) enabled CD players
    • Supported the "Wonder CD" peripheral that allows someone to create music and connect to MIDI-enabled devices
    • Supported a music keyboard called the "Piano Player" that allowed you to create music and learn to use the keyboard
    • Later given a redesign with a softer, more curved look. Some of the extra features were removed, and the joypads were remodeled infra red joypads
  • Sega CDX (named Sega Mega LD in Japan and Multimega in Europe) - A Genesis and Sega CD console with portable CD player abilities, aimed at the more affluent market
    • No built-in screen
    • Could double as a portable CD player. CD control buttons (play, stop, et al.) are on the front of the console. A backlit LCD provided the track number. An extra outline port was provided for stereo equipment
    • Charged by two AA batteries that can only run the CD player. The unit must be plugged in to play video games
  • Nomad - see Sega Nomad
  • Amstrad Mega PC - A clone of an IBM PC with a built-in Megadrive cartidge slot. Capable of task-switching between its Megadrive- and PC mode.
  • Laseractive - A laserdisc player from Pioneer that can plug in modules. One of these modules allow users to play Mega Drive and Mega-CD games. It can display Mega Drive graphics over streamed video from compatible laserdiscs
    • The Mega LD format only had a handful of games using that format
    • 3D Glasses have been produced for compatible discs
    • Other modules could play the TurboGrafx 16 games and the karaoke


More screenshots can be found in the gallery of Sega Genesis screenshots.

Technical specifications

  • Main CPU: 16-Bit Motorola M68000 16 bit processor running at 7.67 MHz
  • Sound SPU: Zilog Z80A running at 3.58 MHz¹
  • RAM: 64 Kbytes
  • ROM: 1 Mbyte (8 Mbit)
  • Video RAM: 64 Kbytes
  • Graphics: VDP (Video Display Processor) dedicated VDP for playfield and sprite control
    • 3 Planes, 2 Scrolling Playfields, 1 Sprite Plane
  • Main sound Chip: Yamaha YM2612 6 channel FM, PC format name .GYM
  • Additional sound chip: 4 channel Texas Instruments PSG (Programmable Sound Generator) SN76489
  • Palette: 512 Colors
  • Color RAM: 64 x 9 KBit
  • Onscreen colors: 61 (up to 1536 using raster effects and Shadow/Highlight mode)
  • Maximum onscreen sprites: 80
  • Pixel Resolution: 320 x 224, 40 x 28 text display mode
  • Signal/Noise Ratio: 14 dB
  • Sound RAM: 8 Kbytes
  • Outputs:
    • Separate R.F aerial and R.G.B outputs
    • (AUX connector - Genesis 1 only)
    • Stereo headphone jack (original model only)
    • 9 pin EXT port (early original model only)
  • Expansion port on the bottom right hand side for Sega CD
  • 2 nine pin controller ports in the front of the machine.
  • note¹: Contrary to popular misconception, Model MK-1631 (Genesis 2) does have a Z80 CPU. Depending on the board revision, the system either has a Zilog Z84C00 or a Custom Sega 315-5676 or similar. Some people thought the Genesis 2 had no Z80 because the Power Base Converter did not work on it. The Power Base Converter does in fact function when connected to a Genesis 2. The only prohibiting factor is the shape of the device, as the Genesis 2's cartridge port is too far forward on the system to connect them without first removing the plastic housing of the Power Base Converter. Since, however, the Z80 is needed for sound production, the Genesis 2 has to include one to play games.

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