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Acorn designed an early home computer for the ´óÏó´«Ã½ in the 1981. The graphical display was assisted by this semi-custom integrated circuit designed by a research team in the Computer Laboratory at the University of Cambridge and manufactured by Ferranti in Manchester.

This early use of an application-specific integrated circuit in a domestic product gave the Acorn computer a significant advantage in terms of performance and cost. Its success also gave Acorn the confidence to make further use of custom chips using design software derived from research work in the university. This led to the Acorn Risc Machine, and ARM is now a multi-billion pound company supplying processor designs for the majority of mobile phones, personal stereos and other low-power electronic devices world-wide.

The circuit was designed by Steve Furber and Sophie Wilson at Acorn, and the semi-custom design was undertaken by Peter Robinson and Jeremy Dion in the university. The initials PR+JD appear in metal 50 microns high on the corner of the chip.

The bipolar chip ran very hot and needed a special heat sink. It was only used in the first 5,000 ´óÏó´«Ã½ machines and was then superseded by a cooler CMOS design.