acorn atom and acorn system series • Re: Alignment of sockets on Oddys System 5 backplane

This web page details the difference between 1U, 2U, 3U and 4U. The height of a rack is measured in Rack Units, written as U. A U is defined as 1¾ inches or 44.45mm. The same standard is used to describe the rack itself, and the equipment designed to go into it. Hence a Eurocard size (as used by Acorn in the System computers) of 100 mm high by 160 mm long is designed to fit inside a 3U rack. See…