0.25 x 106 bit/in2 nondestructive readout coupled-film memory elements [Digests]

The storage density of coupled film memory elements has been increased from 10⁴ bit/in² to 0.25 X 10⁶ bit/in². The size and the density of a chip containing 4250 bits with a penny as background are illustrated, and the enlarged view of the same chip is shown. The high density is made possible by improving flux closures in both the easy and hard directions through the use of thin conductors, thin insulations, and Permalloy keepers. The device storage stability is enhanced to permit NDRO operation through the use of multiple-pulse write and/or hard-direction bias fields. Typical performance parameters are I_W = 60 mA, I_B = 20 mA, and V_s = 150 μV.