Ion-Implanted Magnetic Bubble Memory Devices

High-density magnetic bubble memory devices have been developed by using ion-implanted tracks. Hybrid type devices, composed of ion-implanted tracks for high-density data storage and Permalloy tracks for write and read functions, have an advantage in compatibility with Permalloy devices in commercial use. The characteristics of junctions connecting the two type tracks are improved by a new design in which both ends of a corner Permalloy pattern are superposed with ion-implanted tracks. Functions with ion-implanted tracks and conductors also have been developed to realize a 4 Mbit device. The cache loop method, in which data storage loops are connected with a write/read major line by cache loops, is used to reduce mean access and cycle time of the device.