The European Logarithmic Microprocessor

Faster, More Accurate Computer Arithmetic

Shortly before mid-day on 22nd November, 2002, the world's first logarithmic microprocessor ran its first programme. Designed by a group of researchers at sites spanning almost 1,000 miles of northern Europe, and funded by the EU ESPRIT Long-Term Research programme, the device had been the culmination of seven years of ground-breaking work in the field of computer design. This first programme simply calculated a sine function in 256 steps from 0 to 2 pi. The coming years would see the development of many more advanced industrial-scale programmes. But it served to show that the device, and all the new principles and ideas it embodied, would work in a practical application.

What is a logarithmic microprocessor? It is a computer chip that performs the basic mathematical operations - add, subtract, multiply, divide and square-root - in a radically different way. As a result, it can carry out complex mathematical calculations significantly faster, and also more accurately, than a conventional microprocessor. It opens the way for the implementation of programmes in areas such as graphics, digital filtering, control and communications which have hitherto been impossible to use for practical purposes simply because conventional microprocessors cannot perform the maths quickly enough. Extensive peer-reviewed trials, published in the professional press, demonstrated significant gains in speed and accuracy when compared with the leading commercial alternative.

This device was the major landmark work in an ongoing effort to develop faster, more accurate techniques in computer arithmetic. One drawback was that it required more silicon - a bigger chip - to implement. The next stage in the theoretical work therefore had the objective of reducing this silicon area. Results published in 2016 show that logarithmic arithmetic circuits can now be reduced to the same size as those used in a conventional microprocessor, while also further improving the speed.

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