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 two dimensions plus time will require the most memory, with three dimensions plus time being beyond what can be done using technology that was then available. He concludes that memory will be the largest subdivision of the system and he proposes 8,192 minor cycles (words) of 32-bits as a design goal, with 2,048 minor cycles still being useful. He estimates a few hundred minor cycles will suffice for storing the program. He proposes two kinds of fast memory, delay line and Iconoscope tube. Each minor cycle is to be addressed as a unit (word addressing, Sec. 12.8). Instructions are to