The Acorn Electron was an attempt by Acorn to gain a foothold in the under-£200 market. Riding on the success of the BBC Micro, it was decided to make a cut-down Model B, leaving all the main features intact but stripping it enough to make a viable, cheap alternative to the Beeb.
The Electron hit the market in the summer of 1983. It was a very small machine, tiny compared to the BBC Micro and only slightly bigger than its keyboard. Sadly, this smaller size meant that the machine's expansion abilities were limited to the proprietary edge connector on the back, and the tape interface on the side. It also featured ports for connecting the computer to a television or RGB monitor.
Internally, it was pretty much a stripped-down BBC Micro. A 1.79Mhz 6502A was used as the CPU, with 32kb RAM and 32kb ROM to use. The Electron could do almost everything its bigger brother was capable of, except for the famed Mode 7, as well as having fewer sound capabilities. It was still an excellent machine, and much cheaper than a Model B would cost.
This was quickly resolved when Acorn released the Plus 1 expansion in 1984. This boasted two ROM cartridge sockets, a parallel port, and joystick interface. Later, Acorn followed with the Plus 3 - a 3½-Inch floppy drive. The Plus 1 could be connected to the Plus 3, allowing both expansions to be used at the same time. (They did, however, require their own power supply.)
Built into the ROM was a version of the legendary BBC Basic. To help with programming in BASIC (the Electron being marketed as a family's first computer), printed onto each of the keyboard's keys was a keyword - G had 'GOTO', for example - that would automatically be typed if that key was pressed along with the special function key. Keywords could also be typed in manually. Also included was a full assembly language.
The Electron was a powerful alternative to other micros available at the time, but sadly did not do as well as it could - or should - have. The custom ULA co-processor was difficult to produce, meaning few made it to the shelves in time for Christmas. Demand fell afterward, causing Acorn to have warehouses full of unsold Electrons. However, a dedicated core of fans were there throughout - Electron User was a popular magazine, with many innovative features not found in the equivilant Spectrum mag.