The numerous economic uses of magnetic recording today bear witness to the scope and quality of the development in recent years on the media, trans ducers, kinematics, circuits, and systems involvedo Magnetic recording is already "of age 11 in several different forms in digi tal equipment ο For example, magnetic drums are widely used lor storing moder ate quantities of information such as problem input data, function tables, pro gram sub-sequences, and intermediate results 0 In fact, drums are used wherever random access at rr.ectium speed is wanted among a rather limited number of items ο Another form of magnetic recording, common where storage is needed for much greater quantities of information to which random access is not required, is magnetic tape* One of its typical functions is that of a funnel or speeddifference compensating device, as between the output of many clerks and a sin gle machine capable of handling their combined efforts, or between several ma chines and a high-speed printer able to print their total output* In many of these applications the density of information is not now a prob lem* Their purposes are served economically by the E>0 to 100 and more BITs per lineal inch per track, that are obtained with modern media and heads using tech niques already publishedο On the other hand, further increase in information density usinrr the same media and heads, has real economic value for the kind of random access mer.iory needed in the newer automatic clerical machines 0
RAM Butts Against Density LimitοHere the amount of information dealt with is prodigious and the required filing capacity is correspondingly vasto Here, access time is the bottleneck because it depends on the size of the filing unit* That, at best, iS enormous* And the filing unit's size in turn, depends, among other factors, on the den sity at which the information is filed* In this relatively new field then, where system performance is gauged by its savings in man-hours, a new impor tance accrues to the effective density at which digital magnetic recordings can reliably be made and read* In fact, a few tubes more than normally required might well be justified in the magnetic writer and reader attaining greater than normal density with any given head and medium * Because of our pioneer development of the POTTER RANDOM ACCESS MEMORY -the RAM, that is, with the prodigious digital capacity -we were among the first to reappraise the value of higher density recording in the light of the economics of the newer automatic clerical machines* Under this stimulus we had the good