We didn’t have much luck with this experiment.

Sega’s own historical documentation notes that the original Japanese Mega Adaptor cannot physically fit the TeraDrive because of the shape of the hardware.

That explains why simply attaching the official converter is not straightforward.

It does not answer the more interesting electrical question:

can the TeraDrive’s Mega Drive hardware run Master System software if the converter signals are adapted correctly?

I did not establish a working wiring arrangement in this test.

So this remains an unsuccessful experiment rather than evidence that Master System mode fundamentally cannot work on the TeraDrive.

If anyone knows exactly how it should be wired, feel free to leave a comment.

I always read your comments! :)

Sources