
Lost Generation: The Relay Computers - cfmcdonald
https://technicshistory.wordpress.com/2017/05/10/lost-generation-the-relay-computers/
======
pavlov
My favorite "lost" type of computer is the balanced ternary machines. These
were actually built in the Soviet Union in the 1960s:

[https://dev.to/buntine/the-balanced-ternary-machines-of-
sovi...](https://dev.to/buntine/the-balanced-ternary-machines-of-soviet-
russia)

Programming with trits and trytes!

Unfortunately, domestic Soviet computers were effectively killed by a 1970
decision to base all future efforts on a "Unified System" which was really a
clone of IBM System/360:
[https://en.wikipedia.org/wiki/ES_EVM](https://en.wikipedia.org/wiki/ES_EVM)

Playing it safe by shooting yourself in the head...

~~~
Kinnard
Are there major benefits to ternary computation?

~~~
rwmj
I pulled out my copy of Knuth vol 2 to answer this (pages 190-193):

* You can negate a number by interchanging 1 and ̅1.

* The sign of a number is given by its most significant non-zero trit.

* Rounding to nearest integer is the same as truncation.

By the way if we had balanced ternary computers today, then you wouldn't have
programming languages with signed and unsigned integers. They'd be the same
thing.

Of course the above might be academic if it's more difficult to implement in
CMOS ...

Edit: Also you can argue that the most economical radix is _e_ , and 3 is
closest to this ideal. See:
[https://web.williams.edu/Mathematics/sjmiller/public_html/10...](https://web.williams.edu/Mathematics/sjmiller/public_html/105Sp10/addcomments/Hayes_ThirdBase.htm)

Edit #2: Removed the claim that addition is easier than binary. I misread what
Knuth was trying to say.

~~~
FullyFunctional
Representing binaries numbers with explicit sign bit and the rest unsigned
gets you an even better version of that; this is how floating point handle the
sign.

I'm skeptical of value of ternary. The key behind the success of binary
computers is that binary has great noise immunity; having a _single_ threshold
is way simpler to get working than two or more. (Yet we do go there for NAND
Flash, but note how speed and endurance worsen dramatically as thresholds are
added).

The "most economical radix" is often cited but it's a red herring - it ignores
practical concern of greater importance.

------
deskamess
Wow... the writing, the prose... wish I could put words together like that.

Sample:

""" Fame is partial with her favor, and has not seen fit to bestow any upon
the creators of the panel switch, the type E relay, the crossbar marker
circuit. There are no biographical anecdotes we can summon to illuminate the
lives of these men; the only readily available remains of their lives are the
stark fossils of the machines they created. """

~~~
Animats
Number Five Crossbar is well remembered in telephony, and studied by people
who do high-reliability systems. It was one of the first systems that was
_more_ reliable than its components. No one person is associated with it,
though; it took a big team to develop.

------
Nokinside
You had electronic relays?

Finland had strong import controls directly after the war, so imported
electronics was very expensive. Industry automation still used legacy
hydraulic logic (fluidic logic) to control complex automation in pulp mill
processes in 70's. It was very steampunk.

[https://en.wikipedia.org/wiki/Fluidics](https://en.wikipedia.org/wiki/Fluidics)

Hydraulic logic control is still a useful thing but nobody builds complex
industry automation using them.

[http://ph.parker.com/us/17567/en/hydraulic-logic-element-
val...](http://ph.parker.com/us/17567/en/hydraulic-logic-element-valves-hcd)

[http://www.logichyd.com/](http://www.logichyd.com/)

~~~
mschaef
Pneumatic signaling has been commonplace too... set points for valves, etc.
can be sent by varying the (low) pressure in an air line to the valve itself.

One downside to this is the case where there's condensation in the line and
temperatures go below freezing. You can lose control thanks to the ice that
forms. I remember this causing trouble with powerplants in the 90's during an
ice storm in Houston (which is usually quite warm and humid, so they didn't
think too much about icing.)

~~~
zkms
Yes, there's lots of building automation / HVAC stuff that uses pneumatic
signalling/actuation (like the infamous T-4002 thermostat, look up images of
it, you've probably seen it before!).

Amusingly enough, lots of those pneumatic systems use 3-15 PSI signalling,
which works the exact same way that 4-20 mA signalling works -- with a live
zero so breaks in circuits can be detected!

~~~
mschaef
Early in my career, I did some work on what was essentially a Foundation
Fieldbus to 4-20ma adapter. To get it to control our pneumatic valve for a
demo, we wired it to a 4-20mA to 3-15PSI converter and then to the valve
itself. It was a bit Rube Goldberge-esque, but it served our purpose well.

------
whatshisface
Today, hobbyists build these computer for fun and to test their engineering
mettle:

[http://www.nablaman.com/relay/](http://www.nablaman.com/relay/)
[http://web.cecs.pdx.edu/~harry/Relay/](http://web.cecs.pdx.edu/~harry/Relay/)

------
zkms
I accidentally discovered a year or so ago that Thomas L. Dimond (working at
Bell) invented core rope memory (which the wikipedia page says was "first used
in the 1960s") in the 1940s. His memory got used in phone switches as a fast
and reliable read-only lookup table. Here is a paper about the "Dimond ring
translator":
[http://etler.com/docs/Crossbar/articles/30-AMATranslator.pdf](http://etler.com/docs/Crossbar/articles/30-AMATranslator.pdf)

~~~
Animats
"Writing" was done by manually stringing wires though those big rings. Those
could be changed, but it was a big headache.

It's like classic reverse DNS. There was already a mapping from A to B (phone
number to outgoing wires) and a mapping from B to A was needed for billing
purposes. But B to A info couldn't be obtained from the switch fabric. A
physically separate B to A mapping had to be built and maintained in sync.
There was nothing which inherently made the two match. That was all done by
hand.

The early history of computing was a struggle to find a usable memory device.
Relays were very bulky as memory devices, and none of the relay computers had
much memory.

------
mschaef
This book contains descriptions of many of these, including a particularly
nice discussion of the Zuse Z3:

[https://mitpress.mit.edu/books/first-
computers](https://mitpress.mit.edu/books/first-computers)

Also here: [http://www.inf.fu-
berlin.de/lehre/SS01/hc/zuse/node4.html](http://www.inf.fu-
berlin.de/lehre/SS01/hc/zuse/node4.html)

Interestingly, the machine (built in 1941) used binary floating point. (Not
IEEE754. :-))

~~~
pinewurst
My favorite on this subject is "Reckoners: The Prehistory of the Digital
Computer, from Relays to the Stored Program Concept, 1935-1945" by Paul
Ceruzzi - sadly long out of print.

~~~
mschaef
Thanks... I just ordered a used copy. I remember enjoying one of Ceruzzi's
other books:

[https://mitpress.mit.edu/books/history-modern-
computing](https://mitpress.mit.edu/books/history-modern-computing)

------
ThomaszKrueger
I worked on a project that replaced an electromechanical Telex switch. Four
racks of microcomputer based hardware replaced an entire floor of mechanical
relays.

However it was a marvel to see and hear that thing click and clack all day,
with technicians with their ear trained to detect issues and replace relays by
listening to the switch.

Of course billing was done through a guy on top of a ladder taking large
format B&W pictures of the bank of user's (mechanical) counters.

~~~
NegativeLatency
Happen to have any of those pictures?

~~~
ThomaszKrueger
I wish I had. That was my first job out of school, and I developed the UI for
commands and reports, all through the BAUDOT-code based terminal. Our field
test switch sat on a corner, with some more modern electronic telex terminals
(they were blue), along with EPROM burners for patching, etc. The big switch
was the rest of the floor. So many things I participated in 30+ years ago and
didn't have the idea of taking at least a couple of pictures. Such is life.

------
brutuscat
Even though I only scanned the article, many of those computers appear in
Turing's cathedral G.Dyson[1], book which I enjoyed, given that there is not a
lot of history lessons at the universities (at least the one I went to in
Buenos Aires... UBA).

[1]
[https://openlibrary.org/search?isbn=0375422773](https://openlibrary.org/search?isbn=0375422773)

~~~
alexanderdmitri
I always thought it would be neat to have a CS History lab where every couple
of weeks the students would program with a particular generation of computer,
moving up through time and getting a true sense of the ingenuity at each step.

Might be expensive to house and maintain something like the SSEM or the
CSIRAC, but universities have spent money on sillier things.

~~~
jerf
Emulators are good enough for most students. I did "circuit design" in an
entirely emulated environment and got what I needed out of it as a computer
programmer. It would not have been adequate for a real EE, because for
instance it offered unlimited fan-out and fan-in, but from my perspective I
wasn't losing much to abstract that away.

~~~
alexanderdmitri
True. Mixing emulation in would probably save a lot of work and resources. I
feel like having to do things like manually punch up your programs on cards
and manage with tiny amounts of storage would be a great experience and really
force students to work towards elegant solutions.

I love getting my Dad talking about some of the labs he's worked in over his
career and kind of wish I could get a sense of how much has changed over such
a short time.

~~~
jerf
The other nice thing about emulation is that you get to use modern IO
hardware, particularly keyboards. I can imagine having fun programming on a
Commodore 64; I have a much harder time imagining having fun doing it with an
actual Commodore 64. The keyboards were not all that great by modern standards
when they were brand new, don't get better with age, and _certainly_ don't get
better in a student lab environment :)

------
dwyerm
If this interests you, I've got to throw in a plug for the Museum of
Communications in Seattle. They've got a bunch of old mechanical telephone
switches running. There's something truly awesome -- in the correct sense of
the word -- to be standing inside a computer and hearing the signals passing
around you. It is a unique experience that I strongly recommend.

------
GnarfGnarf
I built a relay computer for a science fair in the 60's. The power supply was
from a pinball machine. The relays were mercury-sealed, from an aircraft.

It had seven words of five bits each (that's all the relays we had). It could
add, subtract and store results.

We got honourable mention.

~~~
Animats
I did that, too.[1] 10 words of 7 bits, addressed with a Strowger switch. Add,
subtract, shift, branch, conditional branch, so it was Turing-complete. The
"paper tape" reader had so much drag I had to use vinyl seat-cover material
for tape.

[1]
[http://www.animats.com/nagle/myfirstcomputer.html](http://www.animats.com/nagle/myfirstcomputer.html)

~~~
cr0sh
This is amazing - thank you for posting about it!

BTW - how old were you (if you care to tell the world!) when you created this
machine?

What made you take pictures of it? Did you keep any part of it, or was it all
relegated to the "junk bin"?

I have found that it is extremely rare that these machines like yours ever
have pictures, much less the writeup like you have created. It doesn't appear
many people created such computers back then, and I don't know of any who
published how they created them. For instance, I have yet to see any old
"Popular Mechanix" style article from the 1960s on "Build Your Own Electronic
Brain" (as I would imagine it would be titled) - but such an electro-
mechanical project would certainly fit those kind of pulp magazines.

Which I find odd. I don't know why these machines - few as they were - were
never publicized; perhaps there wasn't an audience, or because there were so
few, those with the ability to write such an article were fewer? I do know
there was some interest in computing at a "lay-person's" level, because there
were several books on contemporary forms of computing and programming
available in the 1960s (most had enough information to allow a person with
sufficient skills and knowledge to design and build a simple machine - perhaps
you got inspiration from such a source for yours?).

These early "hobbyist" computers, along with early hobbyist robots - represent
the very earliest dawn building toward the microcomputer revolution of the
later 1970s - but the vast majority, if not all of them, are lost to time,
unfortunately.

------
agumonkey
Yann Guidon made a nice little relay computer on hackaday.io

[https://hackaday.io/project/18757-ygrec16-ygs-16bits-
relay-e...](https://hackaday.io/project/18757-ygrec16-ygs-16bits-relay-
electric-computer)

Enjoy

------
terminalcommand
Fascinating read, especially The part about Bell Model III. The machine had
lookup tables, which were actually tab-separated paper. It was an actual
table. They further implemented in the functionality to jump forward and
backward in that table (they called it "hunting").

I don't have much experience in assembly, but reading this article made me
appreciate it more. Assembly basically operates with the same principles as
the first computers.

------
cr0sh
There's another kind of "lost" computer that many don't know about. Actually,
I hesitate to call it a computer, as it didn't compute anything, and none of
the actual machines had anything like a conditional branch operation that I am
aware of...

...they're called "reproducing pianos" (also "reproducing player pianos" and
"reproducers"). Not many were manufactured, due to their complexity, need for
a lot of maintenance, and sheer cost.

Basically, they were a kind of player piano that strived to reproduce the
actual mechanics and technique of the person who "recorded" the original paper
roll. They did this by having additional tracks which handled certain nuances
of the player and such, such that when the roll was played back, the piano
could play in the same manner.

These player pianos were much more mechanically sophisticated than regular
player pianos, and those extra tracks acted like a form of control structure
for the notes being played. I believe that on some of the models meant for
public performances, you could select the song (and it would "wind" itself to
the song, sensing when it had located the piece), and I think they also had an
auto-rewind function - but that was about the limit of their operations.

I've always thought of a CPU - in it's simplest form - as nothing more than a
sophisticated and fast "player piano", with memory being the roll, the word at
an address being the holes in the roll at a certain point, and the CPU being
that which controlled the operations and were instructed by those same holes.
This in fact was actually implemented in some early electronic computers
(known as "drum-based" computers).

The history of computers and computation is a fascinatingly deep and varied
field of study; I encourage everyone to delve into it a bit.

------
dwarman
We built relay computers in HS in the early 60's. There was this street in
London: Lisle St, in the Soho district. One could buy surplus PO 3000 multi-
pole relays there real cheap - up to 10 pole IIRC. These were the relay type
used on the Post Office Telephone exchanges, pre-electronics (up to #5?). In
66 I also discovered a recently published book by Russian authors:
"Introduction to the Theory of Finite Automata" by Trachtenbrot and Kobrinskji
[https://g.co/kgs/EqZYC2](https://g.co/kgs/EqZYC2) which taught me the formal
of the topic using relay logic. I believe the robustness of Russian space tech
was due to use of relays as well as tubes. That book gave me my career,
effectively; turned out to be equally appropriate for electronic logic
circuitry.

------
wernsey
Wonderful read.

These types of articles always puts the amount of computing power I spend to
watch videos of a cat jumping into a box and falling over into perspective.

~~~
mschaef
Around the time of ENIAC, there was a quote to the effect that you could do a
lot with ten million multiplies. I loved the fact that they were thinking in
terms of absolute number of operations (as opposed to rate), and that the
scale is just so vastly different.

------
nasalgoat
Anyone who enjoys relay computers would probably find electromechanical
pinball machines fascinating.

It's quite amazing what they accomplished with mechanical relays!

------
mthwsjc_
Wonderful!

