Synthetic block-replicate bubble memory organization

The design and operation of a novel block-replicate bubble memory organization are described. The organization consists of folded minor loops with the usual true swap switches on one end of the minor loops. On the other end, two paths of an equal number of steps are provided between a simple transfer switch and a merge element. Without current in the transfer switch conductor, bubbles will propagate along the first path which is essentially a portion of the minor loop. With current in the transfer switch conductor, a bubble at the switch will be transferred into the second path wherein a novel passive replicator is located. The bubble will be replicated into two bubbles. One of the two bubbles will propagate into the read channel which leads to a detector while the other bubble will continue on the second path to merge into the "hole" in the minor loop at the merge element. The function of the replicate-transfer switches which require large current is thus accomplished with simple transfer switches which require much less current. The operation of this synthetic block-replicate design has been demonstrated on experimental chips with cell size of 8.4 μm × 7μm. At 200 KHz, a bias margin of 9%, which is limited by the swap switches, is obtained at 50 Oe drive with 20 mA current for the switches. With proximity effects of the input channel eliminated, a bias margin of 19% is obtained and is limited at 180° reverse turns in the minor loops.