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'[OT] : Challenging...(another thought) Magnetostri'
2004\08\01@124424 by Robert Rolf

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Sergio Masci wrote:
>>On Fri, 30 Jul 2004 08:33:03 -0400, John Ferrell wrote:

>>>I think you just described a sonic delay line. IBM was using these for
>>>storage in the late 60's with lengths up to about 500 ms. That size was
>>>touchy, the 50 ms units were rock solid.
>>
>>I think you're wrong there - I believe they were filled with mercury, so were
> anything but solid!  :-)
>
>
> I have seen some delay lines that consisted of a coil of wire. The coil was
> about 8" diameter and only had a few turns (which did not touch each other). I
> belive the wire was a nickel alloy.

Magnetostrictive delay line. The material changes dimension under
influence of a electromagnetic field. Used in early computers,
1980's digitizing tables and a 1960's Frieden calculator I have.
Robert


computing-dictionary.thefreedictionary.com/magnetostrictive%20delay%20line
(storage, history)      magnetostrictive delay line - An early storage device
that used tensioned wires of nickel alloy carrying longitudinal waves
produced and detected electromagnetically.

They had better storage behaviour than mercury delay lines.

[H. Epstein and O.B. Stram, "A High Performance Magnetostriction-Sonic
Delay Line," Transactions, Institute of Radio Engineers, Professional
Group on Ultrasonic Engineering, 1957, pp. 1-24].


www.science.uva.nl/faculteit/museum/delayline.html
Delay line memories
In an acoustic delay line memory, bits are inserted sequentially into
one end of a long metal wire as acoustic pulses, by means of a
transducer (see below). These pulses propagate along the wire at the
speed of sound, until they arrive at the other end where they are
translated back into electrical pulses by another transducer. By making
an electrical connection between both transducers, the loop is closed
and a pattern of pulses, representing the information to be stored,
circulates indefinitely (that is, as long as the power supply remains
uninterrupted!).
Using an arrangement of logic gates, bits can be extracted from or added
to the system. A clock pulse generator is used for defining the time
slots during which read/write transfers can take place; a counter keeps
track of the location of the bit patterns.


www.ingenta.com/isis/searching/Expand/ingenta?pub=infobike://iop/mst/2003/00000014/00000002/art00201
Magnetostrictive delay lines: engineering theory and sensing applications

Measurement Science and Technology   2003, vol. 14, no. 2,   pp. R15-R47(1)

Hristoforou E.

Abstract:

A review of the engineering theory and the sensing element applications
of the magnetostrictive delay line (MDL) technique is presented. The
state of the art of magnetic materials and effects used in sensor design
is overviewed and the operation of MDLs and their basic engineering
properties are discussed. The resulting position, stress and field
sensors based on this technique as well as their most significant
applications are demonstrated. Finally, the industrialization process
and the integration of the sensors with electronic circuitry as well as
their evaluation with respect to the state of the art are discussed.


Language: English Document Type: Miscellaneous ISSN: 0957-0233

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2004\08\01@161403 by Dave Tweed

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face
Robert Rolf <spam_OUTRobert.RolfTakeThisOuTspamUALBERTA.CA> wrote:
> Sergio Masci wrote:
> > >On Fri, 30 Jul 2004 08:33:03 -0400, John Ferrell wrote:
>
> > > > I think you just described a sonic delay line. IBM was using these
> > > > for storage in the late 60's with lengths up to about 500 ms. That
> > > > size was touchy, the 50 ms units were rock solid.
> > >
> > > I think you're wrong there - I believe they were filled with mercury,
> > > so were anything but solid!  :-)
> >
> > I have seen some delay lines that consisted of a coil of wire. The coil
> > was about 8" diameter and only had a few turns (which did not touch
> > each other). I belive the wire was a nickel alloy.
>
> Magnetostrictive delay line. The material changes dimension under
> influence of a electromagnetic field. Used in early computers,
> 1980's digitizing tables and a 1960's Frieden calculator I have.

To expand on that a bit, a problem with acoustic delay lines is that
pressure waves ("P waves" from seismic parlance) propogate at a different
speed through most solids than shear waves ("S" waves), giving rise to a
kind of multipath that can really confuse the issue for persistent storage.

Mercury was used for early delay lines because liquids do not transmit
shear waves at all, but of course, manufacturing them is complicated and
messy.

Magnetorestrictive lines solved the problem by coupling the signal into and
out of the delay line in such a way that only pressure waves were produced
to begin with, also eliminating the multipath problem and reducing the cost
and complexity relative to mercury.

I remember an old "Beehive" terminal in my college computer terminal room
on which you could get chararacters on the screen to change by banging on
the side of it...

-- Dave Tweed

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2004\08\01@172329 by Russell McMahon

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> Magnetorestrictive lines solved the problem by coupling the signal into
and
> out of the delay line in such a way that only pressure waves were produced
> to begin with, also eliminating the multipath problem and reducing the
cost
> and complexity relative to mercury.

I have a wire spiral memory from an old calculator in my "museum". AFAIR
they take the output and inject it onto a variable position sender a small
way down from the start of the line. New data gets injected at the start and
recirculated data into the 'tap". The position is adjustable with an
external screw. Presumably the distance down the line corresponds to the
delay/phase  required in the amplifier which is needed to maintain an
overall gain of 1.


       RM

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2004\08\01@214656 by John Ferrell

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I am pretty sure that the delay lines I worked with were not mercury filled.
(IBM 2702&2703 Communications controllers) They were "black boxes" at the
field level and we swapped out the failures and returned them intact. I
never saw a problem with a small one. The slower lines held a display screen
worth of data in a 2848 Crt controller and they were in constant temp ovens.
That controller ran about 8 crt's, was about 5ft-8in tall, may be 30" x 60"
and used core storage for a character generator....

ALL college computer equipment took a beating...

John Ferrell
http://DixieNC.US

{Original Message removed}

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