Physics of Computer Memory Devices

ELECTRONICS & POWER JANUARY 1977

71

Book Reviews Physics of computer devices

memory

S. Middelhoek, P.K. George and P. Dekker Academic Press, 1976, 402pp. £12.50

A

Since the dawn of civilisation, man has been searching for efficient, reliable and secure means of storing information. In recent times, with the development of automatic-processing engines, the search has concentrated on the physics of the fundamental phenomena which could be exploited to produce memory devices. Having isolated the appropriate phenomenon, a long period of development of the materials must follow, together with the necessary engineering of devices and memory systems to meet the ever-increasing demands for computation and information-carrying media. Success has been achieved by physicists, materials technologists and electronics engineers in an attack on the problems of memory production. A flavour of the many disciplines involved is contained in this book. There are four main types of computer memory which the authors describe in detail: delay-line, matrix, beam-accesible, and magnetic-surface. For each type there is a very brief explanation of the system memory requirements which it satisfies. This is followed by fundamental considerations of the appropriate physics, which then leads to a discussion of the materials technology necessary to produce the components. There have been many interesting memory devices which have not led to significant production components. However, investigation of these has produced knowledge which has led to a better understanding of the total problem. Accounts of these efforts have been included by the authors in this description of the evolution of modern technology. In many places, the authors are able to give only a glimpse of the important ideas. There is, however, an extensive bibliography which provides a starting point for deeper study. There is very little mention of the many problems facing the engineer designing a memory system, such as providing the writing circuits, extracting signals out of noise, distributing the power and signals, coping with wide change in temperature, humidity and other environmental hazards, testing and, finally, meeting the user system requirements. One. would have hoped that the authors would have placed more importance on these aspects and the way they influence the development of the device and its successful use. In the very thorough section on matrix memories, there is an important omission. In the description of the read-only memory, there is no mention of the use of linear components (R, C and L) at the crosspoint, and no mention of the important problem of unwanted paths through the matrix. Much attention is paid to the physics of the magnetic surface material, but very little to recording and reproducing heads, and there is no mention of the flying head. Electronics engineers will find the book a useful up-to-date guide to the phybics and materials technology of memory devices. The physicist and materials technologist may think that it attempts too much, and is hence superficial. It does not give them a full picture of the electronic-engineering problems. D. ASPINALL

Lucas: The first 100 years Vol. 1 The King of the Road Harold Nockolds David & Charles, 1976,349pp. £9.50

Computer oriented learning processes J. C. Simons (Ed.) Noordhof Ley den, 1976, 595 pp.

The Birmingham-based firm of Joseph Lucas Ltd., with its various subsidiaries, is well-known for its activities in many fields from batteries and car components to gas turbines and medical engineering. In 1975 the firm reached the centenary of its founding as a manufacturing concern. Joseph Lucas (1834-1902), assisted by his son Harry (1855-1939), started from literally nothing in 1875 to manufacture the Tom Bowling ship's lamp, and expanded rapidly into lamps and other fittings and parts for bicycles and, later, for motor vehicles. The subtitle of this volume, The king of the road, was the name of their most successful line of bicycle lamps. They formed a limited-liability company in 1897. It was not until 1909 that the firm made anything electrical and it was the First World War that gave them their golden opportunity for expansion into the magneto business — an opportunity that arose mainly because of Harry's good judgment in acquiring the magneto business of Thomson-Bennett Ltd., at the end of 1914. By 1918 they had about 4000 employees.. The first half of this volume deals with this initial 43 years of the Lucas firm in a fascinating story centred on the personalities of Joseph and Harry, who come to life as people, giving vitality to the story. Almost any reader will enjoy this part. The second half carries the history of the company up to 1939, and although much electrical business was involved, the story becomes complicated by the intricacies of business history, with less human and little technical interest. The text is clearly written in a straightforward unpretentious style, is clearly based on thorough research, and is obviously an important contribution to business history. It is also excellently produced. The electrical engineer, and the general reader, will probably be fascinated by Joseph and Harry Lucas and enjoy having the book, but, like this reviewer, may well tire of it before reaching the end. A second volume, carrying the history up to 1975, is due to appear soon. D. G. TUCKER

The subject of learning within computer programs has, in recent years, taken a back seat in favour of precise algorithmic methods. In the belief that this subject is fundamental, a NATO advanced-study institute was held in 1974 at which 28 papers were presented, showing the vivid interest being maintained. This volume contains these papers, divided into the following major categories: adaptive numerical processes; inference of formal grammars; pattern recognition; learning to play games; robotics; problem solving and model formation by inductive inference. Although the papers are written mostly at a reasonably rigorous level, they must not be dismissed as being irrelevant to the solution of real problems. The argument about learning systems is based on the fact that they propose to tackle problems as they really occur, whereas algorithmic methods must be restricted to reduced, or 'toy', versions of real problems, owing to their exhaustive nature. In other words, the practical usefulness of efficiently operating learning programs is self evident, in the sense that they could relieve the user of a great deal of tedious programming. However, it is evident that such programs are still in their infancy. This does not prevent these papers being of interest to the engineer who would like to keep abreast of tomorrow's possibilities. I. ALEKSANDER

Practical instrumentation handbook Bert Earley Scientific Era Publications, 1976,

95pp. £2-80 In this handbook, Bert Earley has condensed much of the useful information that an instrument engineer needs about the plant. He has kept to simple figures and descriptions and left theory and detail to other larger volumes. In checking his tables for thermocouples and resistance thermometers, I had to go to a large number of other sources — without finding a single error. This highlighted the reason for his handbook. My only criticism of the book is that it is so plainly intended for the practising plant engineer to have available at all times that it should have been pocket size. H. A. DOREY

$41.50

Books Received Project planning and building by M. A. Colwell. Newnes, 1976, 102pp. £1.99 Les equations aux derivees partielles; en physique et en mecaniquedes milieux continus by S. Colombo. Masson, 1976, 188pp. F90. Guide to the Japanese and Korean patents and utility models by J. V. Drazil. The British Library, 1976. 135pp. £5 Simple circuit building by P. C. Graham. Newnes, 1976, 112pp. £1.99 Quantum theory of open systems by E. B. Davies. Academic Press, 1976, 171pp. £7.50 Testing methods and reliability: Power by A. Simpson. Macmillan, 1976, 176pp. £3.95 Problems in electronics with solutions by F. A. Benson. Chapman & Hall, 1976, 380pp. £3.95 Crystallographic computing techniques by F. R. Ahmed. Munksgaard, 1976, 502pp. Kr. 336 Handbook for electronics engineering technicians by M. Kaufman and A. H. Siedman. McGraw Hill, 1976, 515pp. £16.20 The art of stage lighting by F. Bentham. Pitman, 1976, 361pp. £7.50 Low-voltage switchgear by T. Schmelcher. Siemens and Heyden, 1976, 134pp. £9.75 Corning research 1975. Corning, 1976, 228pp. These books are available for loan at the IEE Library, Savoy Place