Acorn Electron is a computer made by Acorn for the UK market. Cheaper BBC Micro but not quite... Originally it was made to be compatible with the BBC Micro for the home but at a more accessible price point however it ended up being a cutdown machine with manufacturing problems, weaker sound, slower memory access, slower processor speed when in use and ended up struggling in the market thanks to the ZX Spectrum, Commodore 64 and the launch of the Amstrad CPC. Still has Elite though.
Despite being part of the BBC Micro range, it is considered to be its own machine even on tSR and has its own games for the Electron.
MAME emulates the Acorn Electron with a high accuracy thanks to the preservation work by Nigel Barnes to the point where every MAME release, he adds an extra game or program that was used in the computer.