bubble memory

A solid state semiconductor and magnetic storage device suited for rugged applications. It is about as fast as a slow hard disk and holds its content without power.

It is conceptually a stationary disk with spinning bits. The unit, only a couple of square inches in size, contains a thin film magnetic recording layer. Globular-shaped bubbles (bits) are electromagnetically generated in circular strings inside this layer. In order to read or write the bubbles, they are rotated past the equivalent of a read/write head.

Bubble Memory

This is a conceptual drawing of how a bubble memory circuit works.

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bubble memory - A storage device built using materials such as gadolinium gallium garnet which are can be magnetised easily in only one direction. A film of these materials can be created so that it is magnetisable in an up-down direction. The magnetic fields tend to join together, some with the north pole facing up, some with the south. When a veritcal magnetic field is imposed on this, the areas in opposite alignment to the field shrink to circles, or 'bubbles'. A bubble can be formed by reversing the field in a small spot, and can be destroyed by increasing the field. Bubble memory is a kind of non-volatile storage but EEPROM, Flash Erasable Programmable Read-Only Memory and ferroelectric technologies, which are also non-volatile, are faster. ["Great Microprocessors of the Past and Present", V 4.0.0, John Bayko <bayko@hercules.cs.uregina.ca>, Appendix C]