A transistor digital fast multiplier with magnetostrictive storage

Abstract

The transistor is gradually establishing itself as a useful circuit element, but although individual circuits have proved to be adequately reliable their collective reliability in a more complex apparatus has not hitherto been proved. Accordingly a digital fast multiplier—an important part of any large-scale computer—has been constructed using transistors throughout.Operating at a basic frequency of 125kc/s, the multiplier computes the product of two 32-digit serial numbers in about 4 millisec.The logical design has a novel feature in that the digits of the multiplier are taken in pairs instead of singly.The multiplier can be divided into three parts: the generator of timing waveforms, the arithmetic unit and the storage system. Point-contact transistors are used throughout except in the amplifiers associated with the storage system, where junction units are used. The actual storage elements are magnetostrictive delay lines; some of the results of an investigation into their operation are included as appendices.Out of a total of 84 point-contact transistors, 12 junction transistors and 568 crystal diodes, 3 point-contact units have failed in 7 months of daily operation. No selection of transistors is required. The total power consumption is 50 watts.It is concluded that transistors of the types at present available are well suited to computer circuits and that both the construction and maintenance of the apparatus are facilitated by their use.