The Airy tape: an early chapter in the history of debugging

The discovery of a paper-tape relic consisting of an undebugged program written for the EDSAC computer in 1949 is described. It is believed that this program is the first real, nontrivial application ever written for a stored-program computer. An examination of the program sheds new light on the extent to which the debugging problem was unanticipated by early computer programmers, and the motivation for the development at Cambridge of systematic programming practices and debugging aids. The impact of these early developments on programming elsewhere is discussed