High-speed electronic-analogue computing techniques

The paper describes circuits and techniques of measurement developed for use in an electronic-analogue differential analyser running at high repetition rates. The object has been to explore the upper limits to the speed conveniently attainable in various basic operations. After a general description of the problem and the computer which was ultimately developed, these basic operations are treated in turn. Precision methods have been developed for resetting and releasing integrators and altering the coefficients electronically at repetition rates up to 25 000 per second, making possible extremely rapid automatic search processes of trial and error. A multiplier on the ¿quarter squares¿ principle has been developed, using biased diodes to control the feedback characteristic of an amplifier, giving an output which shows negligible phase-shifts at 50 kc/s. Arbitrary functions are synthesized by approximation in diode-controlled networks. Essential to the efficient use of such high operating speeds has been the development of projective multidimensional displays with an adequate frequency response. Three-and 4-dimensional systems using resistive resolvers are described, and the principles and techniques developed for accurate measurement at high speeds are discussed in detail. The final Section describes measurements made on each of the basic units to evaluate their performance. It is concluded that the potential information capacity of electronic-analogue computing methods is much higher than can be realized by conventional techniques producing single solutions on a 2-dimensional display. With multi-dimensional displays and electronic programming, a hundred-or even thousand-fold increase in information capacity is quite readily attainable with problems requiring systematic search processes for their solution.