Reviews of Books and Papers in the Computer Field

D. COMPUTER SYSTEMSR64-63 Application of Pushdown-Store Machines-R. J. Evey.(Proc. Fall Joint Computer Conference, vol. 25, pp. 215-227; 1963.)

In this paper, the author seeks, using his own words, to "provide atheoretical background for the discussion of certain problems in thegeneration, analysis, and translation of languages." Internal evidencesuggests that the paper is derived from the author's doctoral disserta-tion though this is not explicitly stated. A set of abstract machineswhich are finite-state and to which have been added pushdown storesare defined. An important result is that the inverse of such a machineis proved always to exist. This is used to extend a result of Chomskyto the theorem, "A language is a context-free phrase-structure lan-guage if, and only if, it is the range of a deterministic pushdown-storetransducer." For rigorous proofs of this and other theorems referenceis made to the unpublished doctoral dissertation, so that in a sense,the present paper is more in the nature of an abstract.

The second part of the paper uses the machines defined as a com-mon theoretical background for discussing the Oettinger and Bauer-Samelson algorithms for translating artificial languages, and theYngve and Kuno-Oettinger algorithms suggested for use in thetranslation of natural languages. The pushdown-store machines thusprovide potentially useful abstraction; however, the latter appearsnot to have yielded any very useful new results.

ALBERT A. GRAUNorthwestern University

Evanston, Ill.

R64-64 The SOLOMON Computer-J. Gregory and R. McReyn-olds. (IEEE TRANS. ON ELECTRONIC COMPUTERS, vol. EC-12, pp.774-781; December, 1963.)

In their introductory summary, the authors state that severalpapers have been written and published on various aspects of theSOLOMON computer, and that their paper describes the final designof the computer from a system viewpoint.

If a person has read papers describing various parts of this sys-tem and their proposed uses, he would probably find that this paperties them together in a unified whole. If he has a detailed descrip-tion of this computer which he is going to study, this paper gives agood over-all picture from which to study.-

To a person in my position of having neither read previous de-scriptions of parts of the system, nor being about to study a detaileddescription of it, the paper brings to mind a number of questions ofhow or why various things mentioned are done, or how they are used,which it does not answer.

This paper should include a list of the papers mentioned in thesummary, and where they are published.

In summary, I found the paper interesting, clearly written andtoo short.

0. L. MACSORLEYData Sys. Div.

IBM CorporationPoughkeepsie, N. Y.

R64-65 The GUS Multicomputer System-W. F. Miller and R. A.Aschenbrenner. (IEEE TRANS. ON ELECTRONIC COMPUTERS, vol.EC-12, pp. 671-676; December, 1963.)

This paper describes the Argonne National Laboratory multi-computer, which is centered around GEORGE and FLIP. GEORGEwas built about 1957 to be a self-sufficient general purpose computer.FLIP is a more recent, high speed solid-state computer designed spe-cifically to work in a multicomputer system. In particular, FLIPlacks input-output instructions and depends upon GEORGE forcommunications with peripheral equipment.

In addition to GEORGE and FLIP, multiple independent corememories, magnetic tapes and a drum, and a variety of conventionalperipheral devices, GUS includes two special pieces of equipment.The real time communicator provides analog-digital conversion capa-bilities and control facilities for operating in real time with external

devices, including at present two PACE analog computers. The pat-tern extractor is designed to simulate the perceptron type of opera-tion, in which large amounts of data are processed in accordance withonly a few instructions. GEORGE apparently organizes the data formanioulation by the pattern extractor and processes the results.

Of necessity, the paper describes each of the subsystems onlybriefly. It does provide a general picture of their functions and theirinterrelationships within the system. The characteristics of GEORGEand FLIP are described at somewhat greater length. An interestingitem is the technique by which FLIP automatically keeps track ofthe significance of arithmetic results as a computation proceeds. Theoperation of the pattern extractor and its relation to GEORGE wasnot made clear, although this device seems unusual enough to justifya more thorough description.

One of the interesting aspects of GUS is that it includes both acomputer (FLIP) designed especially for multicomputer operation,and one (GEORGE) intended originally for single computer opera-tion. Valuable insight into the relations among the components ofmulticomputer systems might have been provided by a discussion ofthe ways in which GEORGE was modified to adapt it to its new roleand the effectiveness of the end result.

Similarly, it would be interesting to know how the characteristicsof FLIP were chosen, and to what extent they were affected by thoseof GEORGE, which already existed. Finally, the effectiveness of thismulticomputer system organization is not discussed at all, althoughincreased effectiveness must have been a primary objective. The per-centage of time during which one subsystem is idle while waiting forothers, the difficulty for the programmer of coordinating the opera-tions of the different subsystems and the extent to which the per-formance of one subsystem is enhanced by the special capabilities ofthe others are not discussed at any length. There may not be sufficientoperating experience yet to provide much useful information in theseareas.

The article includes numerous references to technical reports pub-lished at Argonne National Laboratory, which presumably can beobtained on request. These references may provide additional insightinto some of the questions mentioned above.

R. A. KUDLICHAC Spark Plug Division

General Motors Corp.Milwaukee, Wisconsin

R64-66 Parallel Processing in a Restructurable Computer System-G. Estrin, B. Bussell, R. Turn, and J. Bibb. (IEEE TRANS. ONELECTRONIC COMPUTERS, vol. EC-12, pp. 747-755; December,1963.)

The paper describes a fixed plus variable structure computerorganization as an approach to handling specialized computationsmore efficiently. The system consists of an IBM 7090 for the fixedgeneral purpose structure, a supervisory control and an inventory ofrestructurable hardware. This inventory is modular and new circuitsand devices can be added to it as desired. To attain the needed com-putational speeds the program macrocommands are wired in. Thus, tochange the variable portion of the computer, cumbersome rewiring isrequired. To minimize this difficulty, emphasis is placed on the designof modular controls and control models suitable for automatic designhave been formulated.

The paper is primarily hardware oriented and programming prob-lems associated with this type of computer system are not mentioned.The computer system described in this paper is now being completedat the University of California, Los Angeles, and useful informationwill be obtained about some of the systems and programming prob-lems associated with it. This system approach represents one of thesteps in the evaluation of variable computer structures. However, inthe opinion of the reviewer, the requirement of rewiring to gain sys-tem flexibility will seriously limit its acceptance.

E. G. NEWMANIBM CorporationSan Jose, Calif.

1964 649