
1958 Facom 128B Japanese Relay Computer, Still Working [video] - fortran77
https://www.youtube.com/watch?v=_j544ELauus
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angrygoat
A little bit blown away by the biquinary coding used by this machine: at first
it seems like a really odd design choice, but as the video explains at ~ 12:00
it makes fault finding for stuck relays much easier.

A really neat example of a design choice which makes a lot of sense for the
problem domain in question, but it's also just so awesome that someone could
actually see this solution: I can't imagine I would have!

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Aardwolf
The coding is just like a Japanese abacus!

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

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jshprentz
Additional information about the FACOM 128B:

In a July 2019 article, _The Asahi Shimbun_ reports that Fujitsu technician
Tadao Hamada keeps the ancient computer running.
[http://www.asahi.com/ajw/articles/AJ201907280007.html](http://www.asahi.com/ajw/articles/AJ201907280007.html)

On the IPSJ Computer Museum web site, the Information Processing Society of
Japan provides more details about relay-based FACOM computers:

FACOM 128B background:
[http://museum.ipsj.or.jp/en/heritage/facom128b.html](http://museum.ipsj.or.jp/en/heritage/facom128b.html)

FACOM 128A and 128B technical information:
[http://museum.ipsj.or.jp/en/computer/dawn/0012.html](http://museum.ipsj.or.jp/en/computer/dawn/0012.html)

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Animats
Oh, that's a great video. Enough detail to understand how it worked.

As usual in that era, the big problem was memory. Memory in crossbar switches
was so expensive that the programs are on paper tape loops. By then, they
would have known how to put programs in crossbar memory.

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dmix
I'd love a video on how that ticket gate machine works and why it's so
complicated!
[https://i.imgur.com/56mmt5c.png](https://i.imgur.com/56mmt5c.png)

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kristopolous
Looking at it, it appears to be a mostly mechanical solution (you'll need
clocks, configurability based on location, detection of ticket orientation,
etc). They probably got a version working 30 years ago and just stick with
what works.

It's infrastructure level time horizons. When you have 10,000 of something
built into the foundation of something that needs to be operational nearly all
the time, upgrades take years. Look at the new york relay signaling based
metro.

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timonoko
Why didnt they use rotary dialers for input. It would have been funnier.
LM.Ericsson et.al. had ready-made 10 number dial receivers and input register
in a handy 200 kilo rack.

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Aardwolf
180 words of crossbar memory apparently (a word being 69 bits), not 128 bytes
as the name of the computer make me think at first

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2sk21
Loved the video and subscribed to the channel. I really appreciate efforts to
keep old computers systems alive.

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mtsx
Wow, pretty impressive. Sounds like its playing own kind of music while its
doing the calculations.

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dddw
loved that video

