Research and Advances

The serial SABRAC computer designed and built in the Scientific Department of the Israel Defence Ministry has a 5000-location magnetic drum, main store. To avoid a need to resort to optimum programming techniques and to increase its overall efficiency the computer has also been given a 224-word ferrite core store from which the program is obeyed. Transfers between the core and drum stores and to and from the twin paper-tape input and output channels are all available autonomously (concurrently, time-shared). Multiplication and division orders are also autonomous, so that the machine may be executing up to three orders simultaneously. All functions naturally are interlocked. A number of other advanced orders and facilities are also incorporated. In particular, an “Execute” order permits a temporary jump for up to four orders and a second modifier register permits double modification in general and relative addressing of subroutines in particular. Thus the overall effective speed of the machine is much higher than its basic specification would lead one to expect and its design indicates one way in which the concepts of time sharing may be incorporated in “low-cost” computers.

A formula for numerical integration is prepared, which involves an exponential term. This formula is compared to two standard integration methods, and it is shown that for a large class of differential equations, the exponential formula has superior stability properties for large step sizes. Thus this formula may be used with a large step size to decrease the total computing time for a solution significantly, particularly in those engineering problems where high accuracy is not needed.

The IBM 7090 FORTRAN II language requires that a programmer desiring toa mnipulate characters or strings of characters either assign each character to a separate 7090 word or write special subroutines for handling packed words containing 6 characters. The one-character-per-word approach is superior in most cases due to the much smaller machine time it requires. One pays for this speed advantage in additional core requirements, however, plus more complex logic requirements in some cases. Applications exist where considerations of storage and logic make a packed-word approach competitive. One such application, and the one which led to the work described here, was the desire to manipulate information sent via telephone lines by a remote 7090 user to and from the central computer. The results of this work are not completed, but the methods used for manipulating character strings were felt to be of sufficient interest to warrant a report. The following paragraphs describe the approach taken.

This paper concerns some preliminary results of an investigation of certain syntactical features of symbolic programming languages (SPL), which is a part of a wider research in the field of problem-oriented languages for automatic processor construction [1]. Our main aim is to point out certain peculiar features of SPL's which yield a deeper insight into their linguistic nature from a formal point of view, in order to take further steps in the direction of finding a proper way to define them. The general approach suggested here might be of some interest in the broader field of general linguistics, since many languages, including natural languages, show similar properties.

There was the germ of an idea in two previous papers [1, 2] which no one seems to have picked up in almost five years. For certain functions it seems desirable to transform the argument to a short range symmetric about 1.0. I will give examples of this usage for the square root and logarithm function for both binary and decimal machines.