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

[Cary Gray]

The CHM description matches my memory of one of these platters as a table in the nook below the front stairs of Margaret Jacks Hall, around 1982 (then the home of Stanford's CS department). The fact about the platter that most impressed me was how thick it was. The 2 inches quoted on the CHM record seems a little high, but it has been almost 40 years since I used that table to study...

Voy Wiederhold's photo of a display looks like it is from Gates Hall.

	Cary Gray

> On Sep 21, 2020, at 9:49 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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