“By June 1949 people had begun to realize that it was not so easy to get programs right as had at one time appeared. I well remember when this realization first came on me with full force. [...] The EDSAC was on the top floor of the building and the tape-punching and editing equipment one floor below. It was on one of my journeys between the EDSAC room and the punching equipment that "hesitating at the angles of stairs" the realization came over me with full force that a good part of the remainder of my life was going to be spent in finding errors in my own programs.”