Sega Mega Drive / Sega Genesis

This 16-bit console was first released in Japan in 1988, the USA in 1989 and in Europe in 1990. It used a 32-bit Motorola 68000 processor running at 7.61Mhz (PAL) or 7.67MHz (NTSC), with a 16-bit external databus. Main system memory was 64K in size, with a further 64K of video memory and 8K of secondary RAM used by the Z80 (also used as main memory in compatibility mode).

It also had a second processor, usually the Zilog Z80, which handled sound in Megadrive/Genesis mode. When the Master System adapter was added to the system, the 68000 was halted, and the Z80 became the main processor in the system.

The sound generation was provided by two sound systems. Yamaha's YM2612 provided the FM sounds (use the same techniques as the AdLib soundcard), and the SN76489 provided basic three channel tones plus white noise. The SN76489 was also used in the Master System, and was probably used to ensure compatibility with Master System games.

On later models, the system would verify a loaded game to ensure that a certain code was present, this was to prevent unlicensed games from running on the machine. The games were supplied on either CD-ROM or cartridge.

Sega Mega Drive

Peripherals

Meganet / Modem

In Japan a modem accessory was available, this allowed connection to Meganet - an online gaming service, and to online banking services.  Meganet was not all that popular and only a few compatible games were released.

Sega Modem

Sega CD / Mega-CD

In 1991, Sega launched an add-on for the Mega Drive, the Sega CD or Mega-CD. This device allowed play back of audio CDs and loading of games from CD-ROMs. The system had no copy protection because CD burners did not exist at the time, it did have region protection however.

The Sega CD had another 68000 processor built-in, this worked in tandem with the main system's 68000 when playing games. 

World wide sales of this peripheral were 6 million units.

The Mega-CD

Games & Software 

Some of the games for the Sega are: 

• 688 Attack Sub
• After Burner II
• Alien 3
• Batman
• California Games
• Chuck Rock
• Darius II
• DJ Boy
• Double Dragon
• Exodus
• ESPN Baseball
• F22 Interceptor
• Gauntlet 4
• Ghostbusters
• Hardball
• James Pond
• John Madden
• Lemmings
• Monopoly
• Mortal Kombat
• NBA Jam
• Outrun 2019
• Pac-Mania
• Populous
• Rambo 3
• The Smurfs
• Sonic the Hedgehog
• Strider
• Terminator 2: Judgement Day
• Warsong
• WWF RAW
• X-Men
• Zool

Poster

Sega Genesis poster