B1 Computer and User features.

According to the manufacturer’s literature1 the Ferranti Mercury Computer was a high speed machine using hardware floating point arithmetic and with exceptionally large storage capacity. The main applications areas were foreseen as in science and technology, with nine areas listed as:-volume computation matrix algebra X-ray analysis Eigenvalue problems design optimisation linear programming stress analysis relaxation techniques partial differential equations. “When an IBM representative, Samuels, visited Dover Street and saw the electronic floating point in operation he was very impressed. IBM stopped production of their current machine soon after and came out later with a floating point version.” (DBG Edwards, private communication) Mercury was unusual in that it was designed for floating point use exclusively. The integer arithmetic was limited to 10 digits (bits) and thus is difficult to compare with other machines on the basis of fixed point operations. The multiplier was a parallel/serial design, operating on 10 digits in parallel with three serial sections using what later became known as carry save adders. Two multiplier bits where decoded per cycle (Mark I performed 20 digits in parallel in two sections, ‘decoding ’ one digit at a time and also using the ‘carry save ’ technique)