Teradrive
From Sega Retro
One variation of the Sega Megadrive deserves special mention, and that is the Sega TeraDrive. This was an ordinary AMD 386SX-25 PC clone with 1MB of RAM and a 40 MB hard drive, but it also included a built-in MegaDrive as a 16-bit ISA card. The original Japanese TeraDrive was black in color and vended by Sega in in conjunction with a now-unknown Japanese company for use by MegaDrive developers. It shipped with a software development kit (SDK) which made it possible to develop your MegaDrive and Mega CD games (the Mega CD accessory appears to have been an option). The TeraDrive eventually found its way outside of Japan in late 1993 under the sponsorship of Amstrad, the noted computer system vendor. They changed the case color to cream, beefed up the memory to 2 MB, and made the MegaDrive SDK optional. The unit wasn't very successful regardless of market, and this was largely due to its high price (about US$3000). A souped-up version called the MegaPlus was later offered based on a 486DX-33 CPU machine with 4 MB of RAM, but very few seem to have made it out the door. The TeraDrive and its successor have all but disappeared with the passage of time.