This Acorn Atom, known in the Netherlands as Hobbit Computer, is a 1979 build hobbyhomecomputer of the brand Acorn Computers Ltd. The design was by Sophie (Roger) Wilson, who was working for Acorn at that time.
The Atom was bought with your own preference: it was available as a kit to build it from ground up for £120, or you could buy it completely build at the price of £170, both together with an extensive manual, and a very detailed print-out of the layout of the board.
For the end-users it was a machine that was very suitable for using experiments.
The Atom was the predecessor of the in the United Kingdom (and far beyond) very famous BBC-Computer.