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Research and Advances

A cost oriented algorithm for data set allocation in storage hierarchies

Data set allocation in today's multilevel storage systems is usually based on qualitative, ad hoc decisions. While it would be desirable to obtain an optimal solution to this allocation problem, it is clear that the number of parameters involved makes it intractable to straight-forward solution. In such a situation, we must find a set of assumptions which simplify the problem greatly, but which still provide a basis for considering all significant cost elements. This paper presents such a first, quantitative allocation step. It considers many of the significant detailed costs of system utilization, data storage, data staging, and data migration. Although many avenues of further improvement are available, the present algorithm seems to be usefully accurate. As such, it can aid in quantifying the problems of data set allocation, storage system configuration, and new device designs.
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Research and Advances

Computer networks in higher education: socio-economic-political factors

This study presents the results of a nationwide survey of computer networks in higher education conducted during 1971-73. Five major and 18 minor networks were identified. The five major networks included: the ARPA Net, the California State College network, the University of Iowa/Iowa State University network, the Michigan Educational Research Information Triad, Inc., and the Triangle Universities Computation Center network in North Carolina. In-depth studies were conducted of the latter two nets. Based on the experiences of these operating networks, a number of factors are identified for consideration in developing networks. Finally, recommendations are advanced regarding the development of networks in higher education in the future.
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Research and Advances

The Dilogarithm function of a real argument [S22]

The dilogarithm function [1-3], defined by Li2(x) = - ∫x0 (1/z) ln (1 - z) dz, (1) occurs in several different applications in physics and engineering, ranging from quantum electrodynamics, to network analysis, to the thermodynamics of ideal ferromagnets, to the structure of polymers. A new function subroutine is developed which computes the dilogarithm function of a real argument to an accuracy of a few parts in 1015. This program was designed to be included in the usual package of library subprograms relied upon by most users. It employs an alternative computational approach to a previously published algorithm [4].
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Research and Advances

A reply to gentleman and Marovich

Gentleman and Marovich in their short communication [Comm. ACM 17, 5 (May 1974) 276-277] make the claim that for FORTRAN “… the language definitions require that subprograms can be separately compiled…,” citing the ANSI FORTRAN standard X3.9-1966 as their authority.
Research and Advances

Matrix reduction—an efficient method

The paper describes an efficient method for reduction of the binary matrices which arise in some school time-tabling problems. It is a development of that described by John Lions. It has been generalized and adapted to fit into the complete timetabling process; to use a more compact data representation and more efficient processing techniques; to take fuller advantage of possible available previous knowledge about the matrix. And it is designed as a structured program, which can readily be coded by the reader in the high level or low level programming language of his choice. Practical tests of the method have shown it to be a good basis for a realistic timetabling algorithm.
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Research and Advances

A system for typesetting mathematics

This paper describes the design and implementation of a system for typesetting mathematics. The language has been designed to be easy to learn and to use by people (for example, secretaries and mathematical typists) who know neither mathematics nor typesetting. Experience indicates that the language can be learned in an hour or so, for it has few rules and fewer exceptions. For typical expressions, the size and font changes, positioning, line drawing, and the like necessary to print according to mathematical conventions are all done automatically. For example, the input sum from i=0 to infinity x sub i = pi over 2 produces ∑∞i=0xi = &pgr;/2 The syntax of the language is specified by a small context-free grammar; a compiler-compiler is used to make a compiler that translates this language into typesetting commands. Output may be produced on either a phototypesetter or on a terminal with forward and reverse half-line motions. The system interfaces directly with text formatting programs, so mixtures of text and mathematics may be handled simply. This paper was typeset by the authors using the system described.
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Research and Advances

On a solution to the cigarette smoker’s problem (without conditional statements)

This report discusses a problem first introduced by Patil, who has claimed that the cigarette smoker's problem cannot be solved using the P and V operations introduced by Dijkstra unless conditional statements are used. An examination of Patil's proof shows that he has established this claim only under strong restrictions on the use of P and V. These restrictions eliminate programming techniques used by Dijkstra and others since the first introduction of the semaphore concept. This paper contains a solution to the problem. It also discusses the need for the generalized operators suggested by Patil.
Research and Advances

Glypnir—a programming language for Illiac IV

GLYPNIR is one of the earliest existing languages designed for programming the Illiac IV computer. The syntax of the language is based on ALGOL 60, but has been extended to allow the programmer explicitly to specify the parallelism of his algorithm in terms of 64-word vectors. This paper describes the characteristics, goals, and philosophy of the language, and discusses some of the problems associated with parallel computer architectures.
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Research and Advances

Anaysis of interleaved memory systems using blockage buffers

A model of interleaved memory systems is presented, and the analysis of the model by Monte Carlo simulation is discussed. The simulations investigate the performance of various system structures, i.e. schemes for sending instruction and data requests to the memory system. Performance is measured by determining the distribution of the number of memory modules in operation during a memory cycle. An important observation from these investigations is that separately grouping instruction and data requests for memory can substantially increase the average number of memory modules in operation during a memory cycle. Results of the simulations and an analytical study are displayed for various system structures.
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Research and Advances

Professionalism in the computing field

The term professional means different things to different people; nevertheless, there are certain general technical and social standards normally associated with a professional. Further, the term is more generally applied to the practitioner rather than to the researcher. But within the rather broad definition specified, the computing practitioner is, as yet, not regarded as a professional. Each of the four types of institutions—academic, industry, government, and the professional society—that educate, employ, regulate, and mold the practitioner contributes to the “nonprofessional” status of the computing practitioner. The roles of these institutions are examined, various shortcomings are noted, and recommended changes are suggested. In the last analysis, professional status is not bestowed; it is earned. However, universities and industry, specifically, can make certain improvements to help the computing practitioner achieve professional status.
Research and Advances

The new math of computer programming

Structured programming has proved to be an important methodology for systematic program design and development. Structured programs are identified as compound function expressions in the algebra of functions. The algebraic properties of these function expressions permit the reformulation (expansion as well as reduction) of a nested subexpression independently of its environment, thus modeling what is known as stepwise program refinement as well as program execution. Finally, structured programming is characterized in terms of the selection and solution of certain elementary equations defined in the algebra of functions. These solutions can be given in general formulas, each involving a single parameter, which display the entire freedom available in creating correct structured programs.

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