Saturday, July 4, 2015

#124) Your Help Requested - Librascope Disc Memory History?

Nearly 60 years ago, Librascope and IBM were pioneers in the development of rotating disc memories that eventually led to the ubiquitous Terabyte disc memories used in personal computers today. Unfortunately, Librascope's contributions were not well documented, and we need your help. If you, or someone you know of, is familiar with Librascope's rotating disk memory development history during the late 1950's and early 1960's, please read on.

Last month I received an inquiry about Librascope's early rotating disc memories from Tom Gardner, a consultant associated with the Computer History Museum in the San Francisco Bay area. He also maintains a detailed website (click here) where, amongst other things, he documents the timeline for the history of disc memory development since 1956. However, Librascope's important contributions are not yet included, and Tom wishes to correct that.

From 1956 to 1967, the timeline only mentions IBM's contributions. However, from early 1960's advertisements in the trade magazines, we know that Librascope, along with IBM, was one of the first disc memory pioneers. Several of these early ('50's and '60's) advertisements are published on the Librascope Memories website. Click here and scroll through the various ads, and you will find many of them.

Tom has several specific questions, but he is especially interested in the Librascope L100 and L200 Disc Memory Series, which was advertised in the July, 1963 issue of Datamation. He also believes that a minor variation of this series was used in the ill-fated Librascope L-2010 Portable General-Purpose Digital Computer in 1962. If you, or someone you know of, can possibly help Tom, please contact him at: , and please copy me at:


  1. Today I received the following comment from Ray Hand:

    Hi Carl,
    Disk R&D at Librascope continued into at least the early 1970’s. I am sure you know more about the history than I do.

    Never-the-less, when Librascope got involved in sonar research, a need was identified to store large amounts of sonar data and to transfer the data to a monitor at high rates of speed. A unique 96 track "flying head" disk was designed. It was unique in that it had 3 sets of 32 parallel wired read/write heads. The 3 sets of 32 tracks could be switched together “at electronic speeds" under software control. Transferring data via 32 parallel channels instead of one single channel, significantly increased the transfer rate but wait there is more. Bengt Richter then developed software based on the rotational speed of the disk to eliminate latency time. This raised the transfer rate to yet another level.

    We successfully used the disk in sonar display -- proof of concept -- for naval intelligence.

    Another Librascope hardware/software innovation that was ahead of its time, and that we had no idea how to market.

    Where was Steve Jobs or Bill Gates when you needed them.

  2. Hi Ray:
    Any idea as to the date it shipped to the Navy?
    Was there more than one such system or was this just a prototype?
    It sounds like this the became the commercial product, L100 and L200 - without the parallel transfer - comment?

  3. Hi Tom,

    The disk was developed using Librascope Independent Research & Development funds and was not shipped to the Navy. It was however used on Navy sonar display research contracts that were funded by the Naval Sea System Command. It was a prototype and I think only one was built. This took place in the 1971 to 1974 time frame. I was not involved with the L100 or L200 programs but I think that work took place in the mid 60’s which was before the project I described.

    One other note, the air flow over the spinning disk caused the “flying heads” to literally fly, just above, but very close to, the disk surface. If the disk stopped spinning the heads would settle on the disk surface and stick. The disk then had to be cleaned before it could be restarted. One time Librascope facilities wanted to turn the power off for a day to the building containing our laboratory, so I ran an extension cord all the way from the next building to keep the disk spinning.


    Ray Hand