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Research and Advances Sep 1 1969

A base for a mobile programming system

An algorithm for a macro processor which has been used as the base of an implementation, by bootstrapping, of processors for programming languages is described. This algorithm can be easily implemented on contemporary computing machines. Experience with programming languages whose implementation is based on this algorithm indicates that such a language can be transferred to a new machine in less than one man-week without using the old machine.
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Research and Advances Jun 1 1969

Three-dimensional computer display

A stereographic display terminal has been produced using the raster display (BRAD) recently developed at Brookhaven. The system uses a rotating refresh memory to feed standard television monitors. To produce a stereographic display the computer calculates the projected video images of an object, viewed from two separated points. The resulting video maps are stored on separate refresh bands of the rotating memory. The two output signals are connected to separate color guns of a color television monitor, thus creating a superimposed image on the screen. Optical separation is achieved by viewing the image through color filters. The display is interactive and can be viewed by a large group of people at the same time.
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Research and Advances May 1 1969

Automated printed circuit routing with a stepping aperture

A computer program for routing interconnections on a two-sided printed circuit board with a regular pattern of lines, pins (terminals), and vias (feed-through holes) is described. In this program, each interconnection is given a planned routing—typically, down from the upper pin, through a via, and horizontally to the lower pin. From the top, a virtual aperture (i.e. a long horizontal slit) is stepped down the board. The planned routing is the basis for rerouting interconnections within the aperture to resolve conflicts for lines and vias below the aperture and to maximize the effective line usage. If a conflict has not been resolved before the aperture arrives at the lower pin, interconnections are deleted to resolve the conflict. Extensions of this technique to the control of crosstalk between routed interconnections and to the problem of obtaining 100 percent interconnect are also discussed.
Research and Advances May 1 1969

A note on reliable full-duplex transmission over half-duplex links

A simple procedure for achieving reliable full-duplex transmission over half-duplex links is proposed. The scheme is compared with another of the same type, which has recently been described in the literature. Finally, some comments are made on another group of related transmission procedures which have been shown to be unreliable under some circumstances.
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Research and Advances Mar 1 1969

Data communications control procedures for the USA standard code for information interchange

This proposed American Standard has been accepted for publication by USA Standards Committee X3, Computers and Information Processing. In order that the final version of the proposed standard reflect the largest public consensus, X3 authorized publication of this document to elicit comment and general public reaction, with the understanding that such a working document is an intermediate result in the standardization process and is subject to change, modification, or withdrawal in part or in whole. Comments should be addressed to the X3 Secretary, Business Equipment Manufacturers Association, 235 East 42 Street, New York, NY 10017.—E. L.
Research and Advances Feb 1 1969

Exclusive simulation of activity in digital networks

A technique for simulating the detailed logic networks of large and active digital systems is described. Essential objectives sought are improved ease and economy in model generation, economy in execution time and space, and a facility for handling simultaneous activities. The main results obtained are a clear and useful separation of structural and behavioral model description, a reduction of manual tasks in converting Boolean logic into a structural model, the elimination of manual processes in achieving exclusive simulation of activity, an event-scheduling technique which does not deteriorate in economy as the event queue grows in length, and a simulation procedure which deals effectively with any mixture of serial and simultaneous activities. The passage of time is simulated in a precise, quantitative fashion, and systems to be simulated may be combinations of synchronous and asynchronous logic. Certain aspects of the techniques described may be used for the simulation of network structures other than digital networks.
Research and Advances Jan 1 1967

A code for non-numeric information processing applications in online systems

A code has been specifically designed to simplify the internal information processing operations within an online computer system with respect to non-numeric applications, and to maximize the transfer rate of the information channel linking the system and the system user. The code has direct application to problems in areas such as information retrieval, document classification, computer-aided teaching and text editing. This code, called IPC (Information Processing Code), is an 8-bit code set constructed so that 7, 6, 5 and 4-bit subsets can be easily derived from the basic set. The code set is organized so that simple binary operations can distinguish between the numeric alphabetic, special symbol and control character codes. The number of useable characters within the basic set size may be expanded either by use of escape codes included in the set, or by suitable interpretation of otherwise unassigned codes on the basis of the requirements of local environments.
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Research and Advances Jan 1 1967

System performance evaluation: survey and appraisal

The state of the art of system performance evaluation is reviewed and evaluation goals and problems are examined. Throughput, turnaround, and availability are defined as fundamental measures of performance; overhead and CPU speed are placed in perspective. The appropriateness of instruction mixes, kernels, simulators, and other tools is discussed, as well as pitfalls which may be encountered when using them. Analysis, simulation, and synthesis are presented as three levels of approach to evaluation, requiring successively greater amounts of information. The central role of measurement in performance evaluation and in the development of evaluation methods is explored.
Research and Advances Apr 1 1965

Transparent-mode control procedures for data communication, using the American standard code for information interchange—a tutorial

This paper gives the considerations of Task Group X3.3.4 in the area of transparent-mode data communication control philosophy. The appearance of this paper was forecast (under the name of “second-level control”) in the earlier tutorial paper, “Control Procedures for Data Communications,” Task Group document X3.3.4.44, dated May 1964. The present paper elaborates upon solutions to the problems of transparency to the basic ASCII communication control characters, as outlined in the previous paper mentioned above. Moreover, it goes on to cover the additional control problems of handling material such as offline encrypted data or non-ASCII codes by means of systems providing complete character transparency. It does not cover concepts of transparency in which the normal character structure or modulation rate of a system may be abandoned. In conjunction with the earlier tutorial paper, this paper is expected to lead to a proposal for standardization of data communication control procedures using the American Standard Code for Information Interchange.
Research and Advances Nov 1 1964

Time sharing in a traffic control program

The Toronto traffic-signal control system consists of a variety of logically distinct computer programs, all competing for machine time. To satisfy these demands, a time-sharing program has been written whose purpose is to execute, in the order of a predefined priority, the various subprograms within the real-time system. In this paper the more interesting aspects of the time-sharing program are outlined.

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