Wednesday, April 14, 2010

Pretty Bubbles

After having seen a link today on Fark about Matthew Brodrick's computer in War Games computer going on sale, I spent a little bit of time looking at some of the other computers from the era. In doing so, I came across the GRiD Compass 1101, which is purportedly the granddaddy of all modern laptops.

Heavy, hot, sturdy, and allegedly used in the quest for global thermonuclear war, it is a sweet piece of machine. What caught my attention, however, was not its sleek metal case or awesome yellow 80x24 character ELD display but the type of memory the GRiD Compass 1101 used for non-volatile memory.

The GRiD Compass had three modules of bubble memory for long-term storage. This type of memory relied upon "bubbles" of magnetic data. Stored on a two dimensional surface, these bubbles were manipulated by external magnetic fields. By altering these fields, bubbles of magnetism could be shepherded down a magnetic surface toward a read/write head. By connecting the output of one edge of the magnetic surface to the other, bits could be looped back to the other side of the module. Putting many of these loops together, multiple bits could be read in parallel.

Contrasted with the spinning disks of magnetic residue we use to this day, it seems like an elegant solution for non-volatile storage in a historically important but less than elegant era of personal computing.

Unfortunately, bubble memory was not to be. As hard drives improved and dropped in price, bubble memory was abandoned in all but harsh operating environments. Still, the idea of little bubbles of magnetism moving down looped pathways is amazing to me. This type of solid state memory would have been an interesting alternative technology to the modern quantum-mechanically based flash storage devices that are ubiquitous today.

Interestingly, the idea using bubbles as information storage is not over. New research into non-magnetic bubbles continues for "lab on a chip"-style tools, giving bubbles a continuing role in the evolution computational machines.

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