> On Apr 12, 2024, at 3:25 PM, Chuck Guzis via cctalk <cctalk@classiccmp.org>
> wrote:
>
> On 4/12/24 12:04, Paul Koning via cctalk wrote:
>
>> I remember a concept for a very fast magnetic storage system that didn't
>> become a product, as far as I know. The scheme was to build a large array
>> of heads, using IC-manufacturing type techniques, and mount that array in
>> contact or near-contact with a flat rectangular magnetic plate. The plate
>> (or the heads) could move a small amount in one direction. The idea was
>> "head per sector", with the mechanical motion scanning the sector across the
>> head. Given something like piezo-electric actuators it would have been
>> quite fast.
>>
>> There's a neat document in the CWI archives, a course on computer design
>> from early 1948. It has a section about memories, well before core memory
>> was invented. The schemes it describes are quite curious, including
>> photographic memories, selectrons, and various other schemes. Also drum
>> memories, including the rather mythical notion of a drum spinning at 60,000
>> rpm.
>
> That UNIVAC nickel-plated sewer pipe in a box, the Fastrand II used a
> series of solenoids and lever arms for head positioning. I vaguely
> remember a FJCC article describing it.
>
> But fast? Not so much, at least for drum storage of that era. I
> believe there were also microphones incorporated into it, called "ping
> detectors"....
Yes, the Univac Model I acoustic delay line memories. The document I mentioned
is MC report CR-3, by A. van Wijngaarden, 1948, which is online in their
archive but only as a not particularly clear scanned document in Dutch. It
describes six memory technologies: photographic film, fluorescence, electric
resistance (including the notion of a neon cross-bar, which is another way of
describing Bitzer's inherent-memory plasma display panel but more than a decade
earlier), acoustic waves (such as the Univac memory), magnetic tape, wire, or
drum storage, and electrostatic charges (the Selectron is described in detail).
Not all that fast, well, it depends on what you're comparing with. Given tube
logic with cycle times measures in microseconds, quite possibly serial rather
than parallel organization, those acoustic or drum memory systems weren't all
that terrible.
paul
