Developments in magnetic bubble memories

Two new developments for magnetic bubble memories, a bubble propagation circuit and a bubble detector, are presented. The propagation circuit uses a channel with periodic traps coupled with asymmetrically placed bars of soft magnetic material to propagate bubbles nondirectionally with an alternating transverse magnetic field. This structure lends itself to very compact corners and transfer gates used in bubble memories with operating margins virtually identical to those of the straight line propagation circuit. A major-minor loop memory structure based on the channel-bar propagator is discussed. The structure yields independent propagation in the assembly and the storage loops using two mutually perpendicular transverse magnetic fields. The active bubble detector designed to match the excellent properties of the above circuit and to provide a means of nondestructive read-out is also discussed. The detector is based on a magneto-elastic phenomenon and does not require any electric current to operate.