
IBM, sonic delay lines, and the history of the 80×24 display - matt_d
http://www.righto.com/2019/11/ibm-sonic-delay-lines-and-history-of.html
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jhallenworld
Acoustic delay lines were also used in calculators.

[http://www.vintagecalculators.com/html/friden_ec-130_-_ec-13...](http://www.vintagecalculators.com/html/friden_ec-130_-_ec-132.html)

~~~
cr0sh
Something I kick myself every time I think about it was an old desk calculator
I was given as "junk" by the owner of the first software development company I
worked for.

I was 18 years old, and loved to get old electronics to tear apart for the
parts, and this calculator was no exception. It was completely transistor
based, and used nixie tubes for the output. And it had a memory function! But
it didn't work properly, and so I dug into it.

All the while wondering where inside was the "memory function" \- I didn't see
anything that looked like memory, just tons of transistors. But there was one
curious thing - a metal box, very light weight (made of aluminum or
something), with four wires leading in and out of it (two on one corner, and
two on another). It was hermetically sealed, and so I broke out my tools and
attacked it with gusto.

Inside, attached to some ceramic "knobs" which had the wires attached where
they led it - was a coil of wire - 2 or three loops. What was it for? I had no
idea - and tossed it aside.

In the end (after a couple of moves, meeting my now wife, etc - you know,
life), I didn't even keep the nixies - those got sent to goodwill or
something. It was only much later did I realize what I had destroyed.

This was long before today's modern internet - circa 1992 or thereabouts - so
I didn't have any easy way to look things up short of traveling a good
distance to the library. I honestly wish I had kept that calculator whole; it
would have gone nicely with the small "computer museum" collection I have
going today (star of it is an Altair in desperate need of a good cleaning and
restoration).

But back then, I was just a dumb kid, doing dumb things. Ah, well.

~~~
jhallenworld
I used to have two PDP-8s that did not survive moves. If I had only known what
they now sell for on eBay..

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todd8
In my first required digital design lab I picked as a final project the
problem of building a Nim [1] playing circuit. I almost used an acoustic delay
line to hold the game state. This was long before the days of RaspberryPi or
any other microcontrollers. (Our lab at MIT still used the predecessor to TTL
logic known as RTL logic.)

I didn’t end up needing the delay line, I got by with around two dozen flip
flops instead.

How times have changed!

[1] [https://en.m.wikipedia.org/wiki/Nim](https://en.m.wikipedia.org/wiki/Nim)

