The Atom was a progression of machines based on MOS Technology's 6502 microprocessor that the company had been doing since 1979. The Atom was a reduced version of the Acorn System 3 without a disk drive but with an integrated keyboard and cassette tape interface, sold in the form of a kit or armed. The price was about £175.
It had a Motorola 6847 video chip, allowing text modes or two-color graphics. It could be connected to a TV or be modified for an output to a video monitor. The basic video memory was 1 kilobyte but could be extended to 6 kilobytes. A color PAL card was also available.
The local area network Acorn, Econet, was first configured in the Atom.