Sega Genesis started life in 1988 in Japan as Mega Drive. It became available in the United States in 1989 as Sega Genesis. Despite the name, this console was the third version developed by Sega. Anyway, in the United States and some other countries the console is known as Sega Genesis. In Europe it was sold as Mega Drive. The consoles are identical and they don’t have major differences.
The console was powered by Motorola 68000 CPU and it was a 16-bit device. It is interesting that Sega actually made arcade console smaller and more available and hence Sega Genesis started its life. For the sound, Zilog Z80 was responsible. The unit has 900 games in the library which were a huge deal back in a day and considered as one of the most advanced features in the industry. There also was a slot for ROM cartridges that contained one or multiple games.
Sega Genesis was sold as the main rival to NEC PC Engine and Nintendo Super Famicom. Nintendo outsold Sega Genesis in Japan, but it was less successful in the United States. Just to add, Sega Genesis was designed after Master System. It was replaced by Sega Saturn in 1997 although some companies continued making the console up to 1999.
Sega Genesis was sold in 30.7 million units under this name. Tec Toy, a version of the console for Korea was sold in 3 million and Majesco sold 1.5 million. Especially for the console in question, Sega developed multiplayer services these days known as Sega Meganet and Sega Channel, although XBAND was available in some parts of the globe.