An Interview with Walter MacWilliams

 Developing the First “Working” Transistor Application


Oral History – Walter MacWilliams



This switch was a 4-by-10 array, representing the 4 groups of defensive guns and the 10 incoming aircraft whose tracks were being simulated by the Simulator.  (The p-computers calculated, for each projectile, the appropriate probability that that projectile would destroy the aircraft that it was being fired against, and an Electronic Dice Thrower determined whether or not that projectile would destroy the aircraft against which it was being fired.) The Gunnery System Simulator was used to run many attacks, and provided a basis for the design of the ATEWA that was designed, installed in the USS NORTHAMPTON, and tested at sea.


Turning to the Gunnery System Simulator, I designed a “Gun-to-p-computer switch” for the Gunnery System Simulator, using conventional vacuum tubes.  But right at that time, the transistor had been invented, and people were encouraged to find out what this promising new device could be used for.  A few early samples were made available to a few prominent and inventive engineers, including Jean Felker, who was in the same area as I was.  So, I tried out some of the pre-production samples and found that the transistor could perform well in this application, and hence I redesigned my Gun-to-p-computer switch with a transistor implementation, and incorporated it in the Gunnery System Simulator, where it worked well in the program of tests.


Go To MacWilliams Oral History, Pg 6



Oral History – Walter MacWilliams






This is a photo of the Transistor Gating Matrix, a component of the Gunnery System Simulator, as described in this Oral History and built by Walter MacWilliams in 1949 [2] [3].  This is a bottom view, and clearly shows the 40 (10 X 4) matrix, each cell of which was constructed using a single, very early pre-production Type A point contact transistor.  According to Walter,  “In this early period just after the invention of the transistor, a number of circuits were designed using the new transistors.  However, except for my circuit, they were all designed to characterize the transistor as a device, whereas my switch was designed to use the transistor to perform a useful circuit function.  It turned out to have been the very first application of a transistor to perform a useful circuit function.”




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