The Acorn Atom was a 6502 home computer that arrived in March 1980 as a kit you soldered together yourself, or as a finished machine for £50 more.
Why it matters
The Atom was Acorn’s first finished, cased home computer, a cut-down System 3 with the keyboard built in. Sophie Wilson wrote its Atom BASIC, which ran fast and carried a 6502 assembler you could call from the same program. Acorn sold it at £120 as a kit and £170 ready-built. Stairway to Hell’s history of the company puts sales at over 20,000, although 8bs.com says over 10,000, so the exact figure is unsettled. Acorn kept making the Atom until 1983 and sold it alongside the BBC Micro (December 1981) for a while. Both are 6502 machines from the same Cambridge team.
What to check before you buy
- Look under the two voltage regulators. Brown, caramelised board around them means the machine has run hot for years, and the fix (removing the regulators and feeding in external 5 V) is documented but is a modification.
- Ask whether the original 8 V adaptor is included and whether anything has been done to the power connector. Several surviving machines have lost theirs or had the plug cut off.
- Find out which board issue it is (Issue 4 and Issue 5 boards are both being sold) and what has been added. A PAL colour card, extra ROMs, a 32 KB RAM board or an AtomMMC SD interface all change both the price and how original the machine is.
- Power it on and watch for jumbled characters that clear when you press BREAK. That points to the reset circuit and is a cheap fix.
- Press every key and check the chips are seated. The sockets are known to be poor, and at least one Atom needed a keyboard rebuild.
- Disc packs and colour boards are sold separately and are worth more with their cables, manuals and a matching PSU.
