Already in development as a successor to Acorn's previous home micro, the Atom, the Proton ended up being selected for the BBC's computer literacy project, which launched in September 1981. That put it into thousands of schools, where it became the de-facto standard in the UK education sector for many years.

It was exceptionally well specified, and with its MOS Technology 6502 processor running at 1MHz with clever interleaving of video memory, its performance remained at the top end of the scale for 8-bit micros for much of its life. However, although it sold 1.5 milion units, they were mostly in its home market, as Acorn consistently failed to conquer anywhere overseas.

Had it not been for the Proton and its success as the BBC Micro, Acorn would probably not have ended up developing its Acorn RISC Machine processor, which became ARM - the processor used in billions of smartphones around the world.