[TriEmbed] Old computers

Tue Aug 11 10:41:33 CDT 2020

Not so much on the technology side and not quite as old but I found some ISA
card hacking stuff in a recent cleaning.  Two are extenders- to get the card
out of the box to probe on, one 8 bit (XT) and one 16 bit (AT).  I also have
an ISA-8 card with a solderless breadboard on it.  I will included Ed Nisley
book on hacking ISA computers (if I can find it).  All to a good home if you
have a use for it.  I also have some ISA card eprom programmers of similar
vintage and other miscellany.  

John Wettroth
919 349-9875

  _____  

From: TriEmbed [mailto:triembed-bounces at triembed.org] On Behalf Of Rodney
Radford via TriEmbed
Sent: Monday, August 10, 2020 9:40 AM
To: Robert Mackie
Cc: TriEmbed Discussion
Subject: Re: [TriEmbed] Old computers

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_oRC
n_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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