I built a Genesis cart back-up device for my senior project. It wasn't that hard...just found some technical documents and the pinouts/timing and built a simple device that fed it addresses and read the data coming out to the computer. Also talked to some ppl that have built similar devices. I know a few ppl that have tried building that diskdude thing, but apparently the design is flawed... If you want to build a "blank" Genesis/SNES cart (ie like the GB-Xchanger or V64JR) then you cuold use some Flash (word addressed) and have some way to send info to it (parallel port) and have it hooked to the correct pins on the console. It dosen't _seem_ too hard, but I haven't tried building one yet...just been thinking about it.
T.Reid
PS- I did get an 'A' :)