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Perry O. Crawford Jr.

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Early life and education

Crawford was born in Medford, Oregon, where his father, Perry Crawford Sr., an engineering graduate of Stanford University, oversaw construction on the Klamath River Hydroelectric Project. His mother, Irma Zschokke Crawford, also a Stanford graduate, was an artist and a descendant of the Swiss writer and revolutionary figure, Heinrich Zschokke. When his father became president of American Utilities Service Corporation in Chicago, Crawford attended New Trier Township High School in Winnetka, Illinois.

He entered the Massachusetts Institute of Technology in 1936 to study electrical engineering and came to work under Vannevar Bush with fellow student Claude Shannon on the differential analyzer. The theses for his two degrees are considered to be among the earliest modern computer design documents.

His B.Sc thesis, "Instrumental Analysis in Matrix Algebra" was completed in 1939. In summary:

Sketches the design of "an automatically controlled calculating machine" capable of performing a variety of matrix calculations, and incorporating means for scanning digital data represented on punched tape, for adding, subtracting, multiplying, and dividing two numbers, and for storing and printing or punching the data. A punched tape was to be used for sequence control, which would specify the selection of the numbers to be operated on, the operation to be performed, and the disposal of the result.

When Shannon completed his doctorate, Crawford succeeded him in the Center for Analysis as a postgraduate student. His M.Sc. thesis, "Automatic Control by Arithmetic Operations," (1942), continued the theme:

It is the purpose of this thesis to describe the elements and operation of a calculating system for performing one of the operations in the control of anti-aircraft gunfire, which is, namely, the prediction of the future position of the target. It is to be emphasized at the outset that little progress has been made toward the construction of automatic electronic calculating systems for any purpose. ... It can be proposed only that this thesis shows a possible approach to the design of a number of calculating system elements and to the structure of an arithmetical predictor. ... In this introduction, equipment for performing the operations occurring in automatic calculating is described. This equipment includes electronic switching elements, devices for multiplying two numbers, finding a function of a variable, recording numbers, translating mechanical displacements into numerical data, and for translating numerical data into mechanical displacements.

The thesis included a description of a matrix "selector switch," for implementing an arbitrary function or control sequence. Independently invented by Jan A. Rajchman, this device was incorporated, with acknowledgments, in the ENIAC. in a 1975 interview, J. Presper Eckert, a designer of the ENIAC, described another contribution:

I had gotten the idea of using disks for memory, digital memory, from a master's thesis written by Perry Crawford at MIT. He had not built any such disks; it was just speculation.

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