Patent US 4,028,672

A rewritable bubble domain decoder employing a novel switch which is used to determine the path of magnetic bubble domains in a magnetic medium. In contrast to other decoders which are defined and unalterable by their structures, the present decoder has a universal structure, but is amenable to personalization and re-writing by re-loading personalizing (or control) bubbles. A basic element in the decoder is a switch which is characterized by its ability to have its normal function altered in addition to being able to switch between two states. That is, it is a switch in which the normal path direction for bubble domain movement can be changed at any time. In a preferred embodiment, the switch is comprised of a structure for holding a bubble domain which is used to route other bubble domains, together with a structure for overcoming the effect of the routing bubble domain on the input bubble domains to the switch. Thus, a routing bubble domain placed at a articular location remains there throughout the operation of the circuitry rather than having to be removed every time a change in the state of the switch is required. The state of the switch is changed by a superposed and over-powering current. On the other hand, the positions of switches in the decoder can be relocated (hence re-writability) by re-loading the control domains.