point it follows the bubble track indicated by the small dots 1 2 and 3 in particular the bubble propagates around the periphery of element 19 but is blocked by the current i p the bubble moves along the edge of conductor c1 until it is attracted to the poles produced at elements 24 and 25 in response to rotating field h r at this point the bubble has been transferred from input loop il1 to minor loop l1 and then propagates through elements 24 25 26 27 28 and so forth in the usual manner of course when the bubble reaches element 28 it is propagating in minor loop l1 and continues to element 61 and back to element 28 for recirculation the transfer out operation is similar that is the bubble in loop l2 proceeds from element 45 to element 51 in the usual manner however with a transfer out operation the control signal i p is applied to conductor c2 thus the bubble propagating around the periphery of element 51 is blocked by the field at conductor c2 and moves therealong until it is attracted by the magnetic poles at the ends of elements 62 and 63 from there the bubble propagates to elements 64 and 65 until it is attracted to the ends of elements 65 and 70 of loops 0l1 and 0l2 respectively the bubble then propagates through loop 0l2 in the standard manner the phase diagram shown in fig2 illustrates the.