EARLY PROGRAMS ON THE MANCHESTER MARK I PROTOTYPE

The Manchester Mark I Prototype (or Small-Scale Experimental Machine, SSEM, as it was officially known) is generally recognized as the first stored-program computer to successfully execute a program. The SSEM w as a simple machine with only seven instructions (its only arithmetic operation was subtraction) and 32 words of 32-bit memory. Two of the m en primarily responsible for the SSEM, Frederic C. Williams and Tom Ki lburn, published a letter in the 25 September 1948 issue of Nature des cribing the SSEM along with a summary of three programs that were run on it: long division, finding the greatest common divisor of two integ ers, and finding the largest factor of an integer. Given the very limi ted capabilities of the SSEM, the authors set out to discover how all three programs were actually coded.