1958 FACOM 128B Japanese Relay Computer, still working!

1958 FACOM 128B Japanese Relay Computer, still working!



0:00 Intro
0:53 The FACOM 128B
1:53 History of relay computers
5:16 Trip to Mt Fuji and Fujitsu’s Numazu plant
6:12 Detailed look at the FACOM 128B
10:33 Simple example: 3+3, deciphering the lights
12:49 Calculating square root of 2
13:44 Crossbar mechanical memory
17:07 Large calculation demo
21:30 Maintenance
22:34 FACOM and the rise of Fujitsu
23:16 More footage of the 128B in action

This FACOM 128B was designed in 1958 and built in 1959, and is part of Fujitsu’s (and Japan’s) first commercial computers series. It uses over 5,000 relays, and still works to this day! Samtec and Fujitsu arranged for me to see this very special machine in action during a recent visit to Japan.
 
Many thanks to Fujitsu:
Mayumi Funamura
Yoshio Takahashi
Tadao Hamada
and Samtec:
Yasuo Sasaki
Brian Vicich
for making the visit possible.
Special thanks to
Robert Woodhead
for providing precious technical information.

Some relevant links:
Outstanding CHM video on the early machines mentioned here: https://youtu.be/qundvme1Tik

Nice list of amateur relay computer projects: https://hackaday.io/project/11798-relay-based-projects
Viewer @aljawad solves the same problem on a HP-15C pocket calculator from 25 years later: https://youtu.be/dyL5CozJsZU

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