In the early '80 semiconductor memory was relatively expensive and the alternative, floppy disks or harddisks, too fragile and bulky for some applications.
Therefore Intel (yes, they were in the memory business then) and others looked for alternatives. Bubbles were one of them. It is easiest to see bubble memories as floppies, but only the bits (bubbles) rotate. The medium, or 'disk' is stationary.
The bubble technology was 'preliminary' in 1981 but became obsolete within five years, when battery backup-ed CMOS-RAM became affordable.
The following texts and pictures are from the Intel "Memory Components Handbook Supplement 1984" reprint section.
|Picture 1||A magnetic bubble-memory stores data in the form of
cylindrically-shaped magnetic domains in a thin film of magnetic
material (The axis of the cylinder is perperdicular to surface of the
material. The presence of a domain (a bubble) is interpreted as a binary
1, and absence of a domain is firstname.lastname@example.org zero. Bubbles are created from electrical
signals by a bubble generator within the memory and reconverted to
electrical signals by an internal detector, usually a matched pair
of permalloy magnetoresistive sensor strips. Externally the memory is
An external rotating magnetic field propels bubbles through, the film,
metallic patterns, called chevrons, deposited on the film steer the
domains in the desired directions. In these respects, magnetic-bubble
memories are serial high-density storage devices like electromechanical
disk memories. In disks however, the stored bits are stationary on a
moving medium, whereas in the magnetic bubble memory the medium is
stationary and the bits move.
In the absence of power, the stored bits ( 'bubbles") are held intact by the presence of permanent magnets, contained within the memory's shielded package. Hence the non-volatility of data is assured. More info on the Intel 7110 Functional Description page.
|Gespac GESBUL-1||This is a magnetic bubble memory as found on the
Gespac GESBUL-1, a GESBUS-64 system
It was used as data storage in the
Landis & Gyr Bomics work-time registration and access control system.
But that is ancient history.
See this Dvorak blog for more info on what happend with bubble memory.
Latest update: 2011-05-13