Bubble Memory - Prehistory: Twistor Memory

Prehistory: Twistor Memory

Bubble memory is largely the brainchild of a single person, Andrew Bobeck. Bobeck had worked on many kinds of magnetics-related projects through the 1960s, and two of his projects put him in a particularly good position for the development of bubble memory. The first was the development of the first magnetic core memory system driven by a transistor-based controller, and the second was the development of twistor memory.

Twistor is essentially a version of core memory that replaces the "cores" with a piece of magnetic tape. The main advantage of twistor is its ability to be assembled by automated machines, as opposed to core, which was almost entirely manual. AT&T had great hopes for twistor, believing it would greatly reduce the cost of computer memory and put them in an industry leading position. Instead, DRAM memories came onto the market in the early 1970s that rapidly replaced all previous random access memory systems. Twistor ended up being used only in a few applications, many of them AT&T's own computers.

One interesting side-effect of the twistor concept was noticed in production; under certain conditions, passing a current through one of the electrical wires running beside the tape would cause the magnetic fields on the tape to move in the direction of the current. If used properly, it allowed the stored bits to be pushed down the tape and pop off the end, forming a type of serial memory. However, such a system had few advantages over twistor, especially as it did not allow random access.