Logical design of digital computers

BOOK REVIEWS LOGICAL DESIGN OF DIGITAL COMPUTERS, by Montgomery Phister, Jr. 408 pages, diagrams, 6 X 9 in. New York, John Wiley & Sons, Inc., 1958. Price, $10.00. The province of activity for the logical designer of a digital computer lies between the system analysis and the circuit design. There are certain tools and techniques available to the logical designer in performing his duties and this book is devoted to their discussion. Provided these ingredients are mixed with a certain amount of creative genius, according to the author, the contents of the book are sufficient for one to perform the logical design of a digital computer. The book is well written in text-book fashion and cannot be read lightly--it must be studied. This is not a book for someone totally unfamiliar with computers who wishes to be introduced to the field of machine computation. Rather, it is suited for those intimately engaged in the development end of computers. It is also recommended to computer personnel who use computers as a finished tool, such as programmers or numerical analysts ; not because it will advance them in their own spheres of activity--it probably will not---but because it will give them an insight into an area too often taken for granted. Indeed, the computer user may well be so amazed at what he reads of logical design that he will gain an entirely new respect for the machine which has ceased to hold his fascination. Of particular interest is the manner in which Mr. Phister has presented and developed the Boolean algebra. Every theorem, or its dual, is proved formally and then demonstrated by use of diode circuits and Vem~ or Veitch diagrams. Consequently, the theorems are readily appreciated and understood. Several different methods of simplifying Boolean functions are presented, including Quine's method, the Harvard method and Veitch diagram methods. One chapter of the book is presented on the development of memory element input equa-

tions. The techniques are general for synchronous circuits but are of no help in the analysis of asynchronous circuits which operate independently of clock pulses. In fact the techniques described throughout the book are not applicable to the Princeton type machines, whose memory and decision circuits are asynchronous. Another chapter is devoted to the derivation of application eqnations in which the Huffman-Moore digital computer model is used. The remainder of the book is concerned with computer memories, input-output equipment, the arithmetic unit and the control unit. Finally, two computers of a relatively simple nature are designed in full. At the end of each chapter a variety of problems are provided for the reader. Unfortunately, however, the answers to these problems are not included. The extensive bibliographies at the end of each chapter indicate that Mr. Phister has drawn his material from various and recent sources, from men well qualified in the field, and he has successfully woven the many ideas and techniques of logical design into a worthy contribution. LAURENCE C. McGIxx The Franklin Institute Laboratories BEHIND THE SPUTNIKS, by F. J. Krieger. 380 pages, diagrams, 6 X 9 in. Washington, Public Affairs Press, 1958. Price, $6.00. In 1956 and 1957 this reviewer received Parts I and II of a series entitled '% Casebook on Soviet Astronautics." These contained papers and articles which indicated the scope of Soviet activity in the space travel field. Upon mature reflection, one cannot help but be amazed at our complacency in light of what the Russians were telling us. Yet with all this, our satellite efforts were retarded until we have reached the point where it may take years before we catch up with the Russians in the propulsion field. VVe Americans who pride ourselves on our ability, our achievements and our aspirations, will do well to read this revealing work. In I4I