The Acorn ATOM microcomputer is available as a kit of parts for assembly by the user, or as an assembled and tested unit. Many different extensions may be added to the basic ATOM including further memory for user programs or high resolution graphics, an interface to a printer, and the extension ROM which provides floating-point arithmetic and the COLOUR statement. This technical manual contains the information needed in order to construct the ATOM kit and add any of the extensions. Use of the ATOM is described in the book 'Atomic Theory and Practice' and users with assembled and tested ATOMs may not need to refer to this manual.

When purchased directly from Acorn Computers Ltd the assembled and tested ATOM is guaranteed for a full six months if used correctly. The componenent parts of kits are also guaranteed for six months and a fast service facility for assembled kits is available at Cambridge. In general repairs at Cambridge are carried out within two weeks and they are invoiced at around ten pounds plus the cost of any replacement components for ATOMs over six months old.

The ATOM is compatible with the Acorn series Eurocards for the 6502 micro-processor and it can be extended by adding one card inside the ATOM case, or any number of cards in an external card frame. Connection to the cards is by a standard Acorn bus connector, and this is described in this manual. The ATOM can therefore be used to develop programs for later use on larger computer systems, for data acquisition and control purposes, and as a personal computer.

One significant aspect of the ATOM is its capacity for expansion, first by adding further components to the circuit board and then by adding extra boards within the case. One extension allows connection of the ATOM to the Acorn ring whereby a number of computers can communicate and share peripheral devices such as disk drives, plotters, and printers. In this manual the addition of the standard extensions is described.