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Magnetic Bubble Memory

Magnetic bubble memory is a non-volatile data storage medium invented at Bell Labs in 1967. Bubble memory uses a thin magnetic film on a garnet substrate, which forms cylindrical domains when constricted under a magnetic field. These domains, or bubbles, each store one bit of data. The bubbles are created by a generator signal, pushed around the film in racetrack-like loops, and eventually detected by a sense amplifier. Unlike semiconductor memories, bubble memory is sequential access, rather than random access. Conceptually, it is like a tiny magnetic diskette and drive, but with no moving parts. Instead of the disk moving, the bits move.

Bubble memory was a promising technology that was positioned to replace all other forms of memory, but was quickly outpaced by semiconductor memory (speed and cost) and hard disk drives (capacity and cost). The computer industry was already shaped around a well-established split between fast, small-capacity main memory and slower large-capacity storage, and bubble memory was squeezed out in both categories as a costlier, inferior alternative.

Bubble memory may still be occasionally used in some military and industrial applications, where extreme ruggedness and nonvolatility are a requirement. Bubble memory is inherently radiation-hardened: it can withstand the photoelectric effects of a nuclear event, when implemented with specialized nonstop logic circuits which prevent partial loop rotation.

Former manufacturers of magnetic bubble memory include Hitachi, Intel, Motorola, Rockwell and Texas Instruments. Recently, IBM has re-branded the bubble memory concept as 'racetrack' memory, a sort of nano-scale bubble memory which uses an array of tiny wire loops to carry the magnetic domains.

Intel 7xxx Series
 Intel 7xxx Series

Devices included in this entry:

Intel 7110-1 bubble memory (20-pin ceramic LCC; pictured in thumbnail)
Intel D7220-1 bubble memory controller (40-pin ceramic sandwich DIP)
Intel D7230 current pulse generator (22-pin ceramic sandwich DIP)
Intel D7242 sense amplifier (20-pin ceramic sandwich DIP)
Intel D7250 coil pre-drive (16-pin ceramic sandwich DIP)


The Intel 7110 is a high density 1-megabit bubble memory device. The 7110 has 256 data loops of 4096 bits each, arranged as 2048 512-bit pages. The 7110 has separate input and output tracks, as well as other advanced architectural features.

The example pictured here is a 7110-1, the first incarnation of the 7110, with a 20-pin leadless carrier and medium ambient temperature tolerance. 'A' variants (7110A-1, 7110A-4, 7110A-5) have standard tinned through-hole pins. Variants with the -4 suffix (7110-4, 7110A-4) have low temperature tolerance, while -5 variants (7110-5, 7110A-5) have high temperature tolerance. Additionally, there are 'AZ' types with through-hole pins (7110AZ-1, 7110AZ-4) whose performance characteristics are currently unknown.

It should also be noted that some early documentation refers to the 7110-4 as the 7110-0 or simply 7110 with no suffix, and the 7110-5 is listed as the 7110-2. It is unknown whether this abandoned numbering scheme ever made it to production.

Intel subsequently developed the 7114-1, a hard-to-find 4-megabit module in a 20-pin package with tinned through-hole pins.

Intel Magnetic Bubble Storage Data Catalog
BPK 72 Prototype Kit Datasheet
BPK 72 Prototype Kit User's Manual
Intel Solutions Bubble Memory Application Note
7110 1-Megabit Bubble Memory Datasheet
7220-1 Bubble Memory Controller Datasheet
7230 Current Pulse Generator Datasheet
7242 Dual Formatter/Sense Amplifier Datasheet
7250 Coil Pre-Drive Datasheet
7254 Quad VMOS Drive Transistors Datasheet

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Sharp CE-100B
 Sharp CE-100B

The CE-100B is a removable bubble memory cartridge designed for use with the Sharp PC-5000 portable computer. The CE-100B is basically a Hitachi 1-megabit bubble memory module with a few extra layers of armor to help it withstand the harsh environment of regular handling by filthy humans. Nuclear blast? No problem. Secretary's purse? Better add another layer of metal, and a plastic carrying case.

We were unable to open the cartridge without cosmetically damaging it, so you'll just have to imagine what a Hitachi MBM looks like. They were made in Japan in the 1980s, so imagine an Intel 7110 only boxier and more cheaply constructed.

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Texas Instruments TIB S0004-3 2200046-0203
 Texas Instruments TIB S0004-3 2200046-0203

Later variant of the original Texas Instruments TIB0203 92,304-bit bubble memory. Exact specifications are unknown. Like Intel's devices, TI bubble memory uses a major-minor loop architecture.

TIB0203 Bubble Memory (Decode Systems article)

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