The Chairman of the ACM Standards Committee, Julien Green, has charged me with making “more effective use of CACM for communication … to get grass-roots opinions from the ACM membership.” This paper is the first attempt.
A partial dossier on distinguishing between handwritten zero and the letter oh is assembled here. This presentation was triggered by a request for guidance in this matter presented by the United Kingdom Delegation to ISO/TC97/SC2, Character Sets and Coding, at the meeting in Paris on 1967 March 13-16. The matter is just now in the province of USASI X3.6, to which comments might be directed.
Comments will be expected within sixty days [by approximately October 1st].
Artificial Intelligence and Machine Learning
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The simulation of time sharing systems
The development of new large scale time-sharing systems has raised a number of problems for computation center management. Not only is it necessary to develop an appropriate hardware configuration for these systems, but appropriate software adjustments must be made. Unfortunately, these systems often do not respond to changes in the manner that intuition would suggest, and there are few guides to assist in the analysis of performance characteristics. The development of a comprehensive simulation model to assist in the investigation of these questions is described in this paper. The resulting model has a general purpose design and can be used to study a variety of time-sharing systems. It can also be used to assist in the design and development of new time-sharing algorithms or techniques. For the sake of efficiency and greater applicability, the model was implemented in a limited FORTRAN subset that is compatible with most FORTRAN IV compilers. The use of the simulation is demonstrated by a study of the IBM 360/67 time-sharing system.
Structure of a LISP system using two-level storage
In an ideal list-processing system there would be enough core memory to contain all the data and programs. Described in this paper are a number of techniques that have been used to build a LISP system utilizing a drum for its principal storage medium, with a surprisingly low time penalty for use of this slow storage device. The techniques include careful segmentation of system programs, allocation of virtual memory to allow address arithmetic for type determination, and a special algorithm for building reasonably linearized lists. A scheme for binding variables is described which is good in this environment and allows for complete compatibility between compiled and interpreted programs with no special declarations.
An algorithm for generating root locus diagrams
A technique for using a digital computer to draw both ordinary and time-lag root locus diagrams is described. Ordinary diagrams are drawn much faster and more accurately than ever before. Time-lag diagrams, which had been impossible to obtain, are drawn with the same speed and accuracy as ordinary diagrams.
An application of computer-aided typesetting is introduced. A working method is described for publishing ALGOL by computerized translation from Hardware into Reference representation, computerized planning of typographical layout and computerized control of a typesetting machine. The point is made that experts in science, technology, and programming are guaranteed a correct ALGOL documentation without spending valuable time and power on typographic considerations and proofreading.
On the automatic simplification of source-language programs
Methods of simplification that can be applied automatically to programs written in an ALGOL-like language are discussed. The simplifications are based on the form of the program and the knowledge obtained by a processor, without any understanding of what the program is supposed to do. These methods have been implemented in a processor called SURE that accepts a program written in JOVIAL and outputs an equivalent JOVIAL program that may be shorter and may be executed faster than the original.
SURE is described, some of the problems encountered in automatic improvement at the source-language level are discussed, and further types of automatic program improvement are suggested.
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