a tidbit from the emulation general wiki's master system page mentions that the sg-1000 (an early console by sega, i'll connect the dots in a second) shares the same guts with the colecovision, and indeed many master system emulators also have colecovision support. finding this odd, i perused wikipedia about the colecovision and was guided to this blurb in this issue of a magazine called cash box, a (seemingly ongoing in some form) magazine about the music industry that also covered the arcade industry. said blurb can also be seen in the image heading this post
the notion of sega distributing the colecovision in japan is interesting, because... the console never actually saw a release there! instead, sega seemed to have modified the hardware (the same chips, but slightly different layout of memory) before releasing it as their own hardware, the sg-1000. (there's also the sc-3000 that's important in this picture but i'm leaving it out for the sake of brevity)
eventually, sega released a new 8-bit console, the sega mark iii, which boasted backwards compatibility with the sg-1000. the mark iii was then rebranded to the master system when it came time to distribute it in international markets. sega kept the backwards compatible approach when designing the mega drive, so it contained the same cpu (albeit used to manage audio when not running master system games), and its video system was extended from the master system's with new functionality
so if we follow the evolution of the hardware, we can say that the mega drive actually has a bit of colecovision blood in it. funny how that works out
