The probability of information loss at the edges of bubble propagation margins

A study has been made of the probability of error as a function of bias field near the edges of the propagation margin on the minor loops of an experimental magnetic bubble circuit using a computer controlled test apparatus. At the high bias edge of the margin, failure is dominated by the number of times the rotating field is turned off and on. Application of a constant in-plane field in any direction did not improve margins on this circuit. The probability of failure per bubble per operation can be described by a normal probability distribution in contrast to the exponential distribution others have used. This implies that margins decrease more slowly than linearly with the logarithm of the number of operations. At the low bias edge of the margin the transition from reliable operation is sharper, does not depend on the number of times the rotating field is turned off, and is consistent with a flat margin edge as the number of operations increases.