An unusual variant of the Electron was sold by British Telecom Business Systems as the BT Merlin M2105 Communications Terminal, being previewed by British Telecom at the Communications '84 show. This consisted of a rebadged Electron plus a large expansion unit containing 32 KB of battery-backed RAM (making up 64 KB of RAM in total), up to 64 KB of ROM resident in four sockets (making up to 96 KB of ROM in total), a Centronics printer port, an RS423 serial port, a modem, and the speech generator previously offered for the BBC Micro. The ROM firmware provided dial-up communications facilities, text editing and text messaging functions.