Acorn Electron

A 35-year-old Computer by Acorn Computer

Emulated in MAME !

Information for the following ROM(s): electron


Acorn Electron © 1983 Acorn Computer, Limited.

The Acorn Electron was a budget version of the BBC Micro educational/home computer.


Acorn Electron the Computer
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(members only)
CPU: MOS Technology 6502A
Clock rate: variable. CPU runs at 2 MHz when accessing ROM and 1 MHz or 0.5897 MHz (depending on graphics mode) when accessing RAM due to sharing memory access with the video display circuits. The Electron is widely misquoted as operating at 1.79 MHz after measurements derived from speed testing against the thoroughly 2 MHz BBC Micro for various pieces of 'common software'
Glue logic: Ferranti Semiconductor Custom ULA
RAM: 32 kB
ROM: 32 kB
Text modes: 20×32, 40×25, 40×32, 80×25, 80×32 (all text output produced by software in graphics modes)
Graphics modes: 160×256 (4 or 16 colours), 320×256 (2 or 4 colours), 640×256 (2 colours), 320×200 (2 colours — spaced display with two blank horizontal lines following every 8 pixel lines), 640×200 (2 colours — spaced display)
Colours: 8 colours (TTL combinations of RGB primaries) + 8 flashing versions of the same colours
Sound: 1 channel of sound, 7 octaves; built-in speaker. Software emulation of noise channel supported
Dimensions: 16×34×6.5 cm
I/O ports: Expansion port, tape recorder connector (1200 baud CUTS variation on the Kansas City standard for data encoding, via a 7-pin circular DIN connector), aerial TV connector (RF modulator), composite video and RGB monitor output
Power supply: External PSU, 18V AC


The Electron was developed during 1983 as a cheap sibling for the BBC Micro with the intention of capturing the low-cost Christmas sales market for that year. Although Acorn were able to shrink substantially the same functionality as the BBC into just one chip, manufacturing problems meant that despite pre orders of 300,000, only 30,000 machines were available for the Christmas period — to the extent that some shops reported eight pre-sales for every delivered machine, there were even press reports of fights in places such as Rumbelows over the slim shipments of machines, as parents could not get an Electron, they turned to other readily available machines such as the ZX Spectrum and Commodore C64.

Unfortunately for Acorn, in the months after Christmas, the firm was tied to accepting delivery of the remaining pre order machines, and there was a warehouse in Welling-borough with unsold machines piled up to the ceiling.

This was a blow from which the machine never fully recovered, although games sales for it would ultimately outstrip those of the BBC Micro. Following Olivetti's 1985 cash injection into Acorn the machine was effectively sidelined.

With hindsight, the machine lacked the RAM (a typical program would need to fit in only around 20 kB once display memory is subtracted) and processing power to take on the prevailing Sinclair ZX Spectrum and Commodore C64. Despite this, several features that would later be associated with BBC Master and Archimedes were first features of Electron expansion units, including ROM cartridge slots and the Advanced Disc Filing System — a hierarchical improvement to the BBC's original Disc Filing System.

While it may not have been as popular as the Spectrum, Commodore C64 or Amstrad CPC, it did sell in sufficient numbers to ensure that new software was being produced right up until the early 1990s. This meant the Electron had a lifespan not much shorter than those more popular micros and much longer than competitors such as the Oric-1 and Dragon 32.

Machine's bios.
Machine's picture.