A 375-NANO'SECOND MAIN MEMO'RY SYSTEM UTILIZING 7-Mll CORES

It has been postulated that ferrite and thin film memories should have approximately the same ultimate speed limits.! For this to be true in the case of conventional toroids, it is clear that the storage element must be made smaller and the storage array made more compact with~ut increasing noise. In the past, techniques such as partial switching and two cores per bit2,3 have gone a long way toward reducing the time and energy associated with the switching of storage cores, and these combined with a word-organized storage array have enabled the technology to reach 0.5-microsecond cycles with core sizes of 0.020 inches inside diameter. At this point,.however, a number of problems were encountered which became limiting factors when higher speeds were attempted. Ferrite . materials' development has resulted in very little progress in reducing the switching coefficient of ferrite and there is little hope of reducing it, say by an o;der of magnitude, to make it comparable with thin films. Therefore, the alternative is to increase the coercivity of the material to obtain faster coincident-current switching. With 20-mil cores this increases power dissipation in the drive system beyond anything achievable with economical