Acorn Computers released the Atom in March 1980 as hobby computer. The Atom was de predecessor to the famous BBC Micro, which sold well in both the UK and elsewhere. The BBC Micro was initially an upgrade for the Atom and was originally known as the 'Proton'. The Atom was sold until the BBC Micro's introduction in 1982.

The Acorn Atom was designed by Sophie Wilson, a now-former employee of Acorn and later the co-designer of the ARM architecture family. The Acorn Atom was made from the same casing as the keyboard used for the Acorn System line. The Acorn Atom was also more than able to be experimented with by its user.

The Atom was, in effect, an economised Acorn System 3. Though the Atom did not have a disk drive (which the System 3 did have), the Atom had an integrated keyboard and a cassette interface. The Atom had 2 KB RAM and 8 KB ROM, though this was expandable to 12 KB in both RAM and ROM.

The Atom was sold in two types of packaging; it was available as a do-it-yourself construction kit for £120 or, for £50 extra, you could buy it already assembled. Both packages included an instruction manual and a print of the board's layout. Both documents were highly detailed. The price for a fully expanded Atom could cost the consumer more than £200 at the time.

In the Netherlands, the Acorn Atom was also known as the 'Hobbit Computer'.