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

Salem Elzway salem.elzway at gmail.com
Mon Sep 21 10:29:59 PDT 2020

Hi everyone,

Les Earnest, former executive director of SAIL, uses the only existing (?)
Librascope Disk File for a coffee table in his living room (see the image
in the SAIL ebook Tom linked to).  That is, assuming he hasn't gotten rid
of it since I interviewed him at his home last February (2019)...


On Mon, Sep 21, 2020 at 11:49 AM <thomas.haigh at gmail.com> wrote:

> Hello SIGCIS,
> 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.
> https://exhibits.stanford.edu/feigenbaum/catalog/ct397kv6234
> According to these pictures of the display,
> http://infolab.stanford.edu/pub/voy/museum/pictures/display/1-MD-MemDisk2.htm
> 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).
> https://www.computerhistory.org/collections/catalog/102682858
> On the other hand, an ebook about the SAIL DART archive gives a 4 foot
> diameter (i.e. approx.. 48 inches).
> https://www.saildart.org/simple/booklet/SAILDART_PREVIEW_2020_0330_good.pdf
> 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,
> Tom
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Salem Elzway
PhD Candidate
Department of History
University of Michigan
salem.elzway at gmail.com
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