[TriEmbed] Old computers

Mon Aug 10 12:00:00 CDT 2020

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... ;-)
>>>>>
>>>>>
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> --
Gregg Tracton: tired, retired & inappropriately unattired (PJ's)
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