Aha! Found it! I'd been looking for this. Recommended once by YouTube, and then lost.

Paint.App
… on GEM
… on DR-DOS
… on an 8086 PC emulator
… on a Raspberry Pi
… running as a second processor using a BBC Master 128 for I/O.

There's a follow-up re-hash video by @WiFiSheep that explains the tokenization problem with the CIRCLE statement.

Of the many people who have run #Elite on a Pi second processor, none seem to have thought about switching to the PDP-11 emulation and trying to run some early Unix. But seeing DR-DOS on a BBC Master is pretty wild.

https://youtube.com/watch?v=mP7fiaync5E

#BBCMaster #PiCoPro #PiTube #SecondProcessor #DRDOS #AcornTube