Frequency of exceedance any peak exceeding is . Its complement, is the probability of exceedance, the probability that has been exceeded at least once by time . This probability can be useful to estimate whether an extreme event will occur during a specified time period, such as the lifespan of a structure or the duration of an operation. If is small, for example for the frequency of a rare event occurring in a short time period, then Under this assumption, the frequency of exceedance is equal to the probability of exceedance per unit time, , and the probability of exceedance can be computed
First Draft of a Report on the EDVAC to denote a unit time delay, as time delays must be accounted for in a synchronous design. He points out that in one microsecond an electric pulse moves 300 meters so that until much higher clock speeds, e.g. 10 cycles per second (100 MHz), wire length would not be an issue. The need for error detection and correction is mentioned but not elaborated. A key design concept enunciated, and later named the Von Neumann architecture, is a uniform memory containing both numbers (data) and orders (instructions). "The device requires a considerable memory. While it appeared that various parts of this