Sega released this beast in conjunction with IBM in 1991. It is essentially a 286 computer with a Megadrive slapped inside of it. Sounds like a good idea (this was several years before home computers were fast enough to do game console emulation,) but the problem was by 1991 a 286 machine was already two generations behind the curve (in 1989 the 486 processor was already available and the first Pentium processor debuted in 1993.) So sales were low, and very few were produced. This of course makes it one of those Holy Grails highly sought out by collectors. Here's some info I ganked off some other website:
"Only three models were released, a low-end Model 1, with 640k RAM and no HD, a Model 2 with two floppies and no HD and 1MB RAM, and the high-end Model 3, with one floppy, 2.5MB RAM and a 30MB drive. All three shipped with the same software and accessories, which is to say they didn't come with anything much. The IBM drivers included with the TeraDrive enabled properly written software to install software in RAM and run them on native MegaDrive hardware. One of the very few software titles released for the TeraDrive was Puzzle Construction, which included a PC-side editor suite for changing the features of a falling-block puzzle game, which was run on the MD-side."
The price of this thing is appallingly high, I've seen them on some websites for as much as $4000 plus. Yikes. I mean, come on man, nowadays a 286 is pretty much worthless. But I guess if you've absolutely got to have everything with the Sega brand name on it then be my guest.