[TriEmbed] Old computers

Mon Aug 10 12:50:39 CDT 2020

Robert is correct - it works by twisting the wire, and has a period of
about 3-4 milliseconds.

There is a good description of it here and an engineering drawing of the
actuating device:

https://www.oldcalculatormuseum.com/friden130.html

On Mon, Aug 10, 2020 at 1:09 PM Robert Mackie <rob at mackies.org> wrote:

> I don't think it works at nanosecond speeds. More like milliseconds
>
> The wire is physically twisted by an actuator, and the physical twist
> moves down the wire at a predictable rate, like a bend in a jump rope when
> you jerk one handle.
>
> At the other end is a sensor that reads the twist and reapplies it to the
> actuator. (Refreshing the values on the medium constantly as the arrive at
> the end of the physical wire) This holds memory in the dynamic physical
> state of the medium.  A read action waits for the right segment of time
> (address) to happen and reads out the twist state. A write action waits for
> the correct address to arrive and then does NOT repeat the input but
> actuates according to the value to be written.
>
> The unit I showed had an 8 bit register with 8 externalized wires. Send
> write, send address, send value. Wait for indication of successful write.
>
> Send read, send address, wait for indication of successful read,
> acknowledge, take 8 bits off interface. Or something very close to that.
>
> Rob
>
> On Mon, Aug 10, 2020, 1:00 PM Gregg Tracton <tracton at gmail.com> wrote:
>
>>
>> how does this delay circuit work?
>> is it just using the fact that signals flow down lines at 1’ per
>> nanosecond, so a 50’ length delays for 50 ns?
>>
>> -g
>>
>> On Mon, Aug 10, 2020 at 9:40 AM Rodney Radford via TriEmbed <
>> triembed at triembed.org> wrote:
>>
>>> This is the first time I have seen another one - thanx for the photo and
>>> the back story. If you find the patent number, I would be interested in
>>> seeing it.
>>>
>>> After watching someone interface an Arduino to core memory at the
>>> virtual computer festival, I wondered how difficult it would be to
>>> interface an Arduino to this delay line. Mine has 12v stamped on the board,
>>> so that gives me some hint as to voltages, and the electronics on the board
>>> is simple, so should be possible to sketch out a schematic of the read and
>>> write circuits.
>>>
>>>
>>> On Mon, Aug 10, 2020 at 3:10 AM Robert Mackie <rob at mackies.org> wrote:
>>>
>>>> Rodney,
>>>>
>>>> Oddly enough, I see the photos attached.
>>>>
>>>> re:  a mechanical delay line
>>>>
>>>> My dad worked for IBM way back in the day, as an electrical engineer.
>>>>
>>>> He left me copies of a few of the patents on which he was listed as an
>>>> inventor. One of them is exactly such a device, used at the edge of
>>>> telephone switching networks (I think - edge of some network anyway) to
>>>> hold state. Much cheaper than core memory for the time, and could hold 2048
>>>> bits, with a latency of something like 50ms. Somewhere I have the paperwork
>>>> for the patent application. Now I'm curious if it was a refinement or the
>>>> first of its type. Never thought about it before.
>>>>
>>>> But this is one where he had kept a physical example, one they had to
>>>> cut open during testing. I knew exactly where it was so I just snapped a
>>>> photo with my phone:
>>>>
>>>> http://mackies.org/mechanical_delay_line_dynamic_memory_ibm.jpg
>>>>
>>>> Figured it would be interesting to see and compare.
>>>>
>>>> Rob.
>>>>
>>>> On Sun, Aug 9, 2020 at 6:14 PM Rodney Radford via TriEmbed <
>>>> triembed at triembed.org> wrote:
>>>>
>>>>> Nevermind, the photos 440k were deemed too large to be sent by the
>>>>> TriEmbed server.
>>>>>
>>>>> Sorry you will not be able to see them.
>>>>>
>>>>>
>>>>> On Sun, Aug 9, 2020 at 5:38 PM Rodney Radford <ncgadgetry at gmail.com>
>>>>> wrote:
>>>>>
>>>>>> I forgot to include the photos...
>>>>>>
>>>>>>
>>>>>> On Sun, Aug 9, 2020 at 5:37 PM Rodney Radford <ncgadgetry at gmail.com>
>>>>>> wrote:
>>>>>>
>>>>>>> One of the passions I have put time in the last few months are
>>>>>>> collecting and learning about old vintage computers.
>>>>>>>
>>>>>>> I currently have:
>>>>>>> * IMSAI S-100 system
>>>>>>> * Sol-20 S-100 system
>>>>>>> * TRS-80 Model 1 and 4p
>>>>>>> * Two Apple IIe systems
>>>>>>> * Kaypro 10 luggable system
>>>>>>> * TI 99/4
>>>>>>>
>>>>>>> I used to have a much larger collection including
>>>>>>> * Burroughs L5000 (google about that beast)
>>>>>>> * TRS-80 Model 2, 3 and 4
>>>>>>> * Zerox CP/M system (I think I still have it, but can't find it)
>>>>>>> * Pet Commodore 2001 (loaned to a 'friend' - never got it back)
>>>>>>> * several Apollo systems
>>>>>>>
>>>>>>> While I wish I could have kept all the old systems, it just was not
>>>>>>> possible due to storage space constraints.
>>>>>>>
>>>>>>> Back in highschool, a teacher gave me her old 4-function Singer
>>>>>>> (yes, the sewing machine) calculator. I, of course, took it apart... ;-)
>>>>>>>
>>>>>>> I did keep two parts from the calculator - the keyboard (mechanica
>>>>>>> marvel) and the storage device (a mechanical delay line).
>>>>>>>
>>>>>>> When I first looked inside, I saw the aluminum box with the words
>>>>>>> read amp and write amp on it, and I *knew* I had found core memory.
>>>>>>> Then I opened it and was completely surprised with what I found. It
>>>>>>> is a magnetostrictive delay line memory device - memory was stored by
>>>>>>> twisting the wire at one end, and the twist would propogate through the
>>>>>>> long coil and out at the other end. By varying the direction of the twist,
>>>>>>> data could be stored temporarily, and it was then sent back in again for
>>>>>>> storage again.
>>>>>>>
>>>>>>> The other item I kept from the calculator was the keyboard. On each
>>>>>>> keypress, the key was decoded with gears and levers that move magnets over
>>>>>>> reed relays - as that was more economical than a simple electronic keyboard
>>>>>>> decoder.
>>>>>>>
>>>>>>>
>>>>>>> Here is a link to information about the calculator (and some info on
>>>>>>> the delay line):
>>>>>>>
>>>>>>>
>>>>>>> https://www.oldcalculatormuseum.com/friden1160.html
>>>>>>> <https://www.oldcalculatormuseum.com/friden1160.html?fbclid=IwAR1jtFCm3O_oRCn_hLop43h5fNOtefDedwSv1hVtzH7vUv_TSvCC4qqGjEs>
>>>>>>>
>>>>>>>
>>>>>>> Photos included of the delay line and keyboard. If we were meeting
>>>>>>> in person Monday, I would have brought them out for show and tell.
>>>>>>>
>>>>>>> I also really enjoyed the virtual vintage computer festival I
>>>>>>> mentioned earlier. Some really good talks on that, and my first of four
>>>>>>> books I ordered arrived today - the ENIAC Technical Reference manual, as
>>>>>>> written by one of the first female programmers on it.
>>>>>>>
>>>>>>>
>>>>>>> PS: If you have any old systems that need a home let me know. I
>>>>>>> really should have grabbed the TRS-80 Model 100 that I brought last year
>>>>>>> that was given to the club, but I let someone else take it (any idea who
>>>>>>> grabbed it?)
>>>>>>>
>>>>>>>
>>>>>>> Anyway, back to current time where I need to finish up an IoT device
>>>>>>> for work... ;-)
>>>>>>>
>>>>>>>
>>>>>>> _______________________________________________
>>>>> Triangle, NC Embedded Computing mailing list
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>>> --
>> Gregg Tracton: tired, retired & inappropriately unattired (PJ's)
>>
>
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