[SIGCIS-Members] New biggest hard drive candidate: Librascope Disk File

thomas.haigh at gmail.com thomas.haigh at gmail.com
Mon Sep 21 09:49:10 PDT 2020



My new candidate for largest hard drive is the Librascope Disk File, as used
at SAIL. According to this letter from Ed Feigenbaum, only two were
produced. Stanford acquired one of them for $300K in 1967, but a year later
a "massive malfunction" destroyed half of its capacity, leading to a lawsuit
settled out of court. In 1976 it was decommissioned, but at least one of the
platters was saved and displayed.


According to these pictures of the display,
m it was a "head per track" unit (i.e. more like a flat drum memory than a
regular disk) which would solve the problem of large access times moving a
head over such a large disk. The overall drive had six platters and weighed
5,200 lbs, to store 1,120,665 32-bit words (ie about 4.27MB) per side. So
about 50MB total. 


An exhibit page at CHM documents what seems to be a platter from the same
drive, claiming a 5 foot diameter (i.e. approx.. 60 inches).

On the other hand, an ebook about the SAIL DART archive gives a 4 foot
diameter (i.e. approx.. 48 inches).

Both are comfortably larger than the 39 inch diameter for the Bryant drive.
And as both platters are still around, someone should be able to make a
precise measurement for the record books.


Best wishes,





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