"In early trials it was a dance of death leading to no useful result, and what was even worse, without yielding any clue as to what was wrong. But one day it stopped and there, shining brightly in the expected place was the expected answer. It was a moment to remember ... and nothing was ever the same again," - F.C. Williams

On June 21, 1948, the Manchester Mark I Prototype (also called the Small-Scale Experimental Machine or SSEM) became the first stored program computer to successfully execute a program. A unique feature of the SSEM was its use of CRT memory.

The SSEM was a small prototype - it had only 32 words of memory and seven instructions. Code and data were entered directly into the memory of the computer while results were read directly off the CRT memory since it could be viewed directly. Because of its limited size programming the SSEM was particularly challenging. However, in a letter published in the 25 September 1948 issue of Nature, F.C. Williams and T. Kilburn mentioned a number of problems the SSEM was able to solve.

"Examples of problems that have been carried out are: (1) Long division by the standard process.. (2) H.C.F. by the standard process ,,,[and] (3) Factorizing an integer"..

We will examine how these problems were coded on the SSEM. In particular, the code for "Long division" is interesting since it was written by Alan Turing.
 
 

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