1958 FACOM 128B Japanese Relay Computer, still working!

1958 FACOM 128B Japanese Relay Computer, still working!

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
for making the visit possible.


  1. Hey Birt! on November 29, 2019 at 6:52 pm

    The first electronic (tube based) digital computer was the Anastoff Berry Computer which was built before WWII. In fact the ideas used to build the Eniac were taken from Anastoff with no credit given to him at the time.

  2. Damien Drouart on November 29, 2019 at 6:54 pm

    I could listen to that machine working all day long.
    How the timing done? There should be a motor somewhere that define the working "frequency" of some sort.

  3. edgeeffect on November 29, 2019 at 6:55 pm

    I’ve been listening to a series of (i suppose they must be) "podcasts" recently called "How I became a phone phreak" and he talks about crossbar-3 and crossbar-4 exchanges quite a lot…. thanks for finally explaining where "crossbar" comes from.
    The all electronic computers might be faster and everything…. but nothing in this world _sounds_ quite as cool as a relay computer:

  4. Phil on November 29, 2019 at 6:56 pm

    I thought you were going to ask him to divide by zero. Great vid-jay-oh!

  5. mumblbee bee on November 29, 2019 at 6:57 pm

    Harsh on your translator, but otherwise a lovely video, thank you!

  6. Dekkia on November 29, 2019 at 6:58 pm

    A few month back I found out about this computer and quickly discovered that most written information about it was in japanese. I also could not really find proper photos to see how it looks like.
    Thank you so much for making this video. It’s truly an impressive machine.

  7. iNerdier on November 29, 2019 at 6:59 pm

    Skip ahead? I don’t think you understand why I watch these videos…

  8. Robert Woodhead on November 29, 2019 at 7:00 pm

    As someone who got a chance to see this machine earlier this year (and on a maintenance day, so I met the full team dedicated to keeping this machine alive), I can state with authority that seeing this device in operation should be on the bucket list of every lover of computing history. It not only features a bunch of clever innovations that made it more powerful, but it has a visceral impact that is similar to that which you get when seeing the Difference Engine in operation.

  9. Vince I on November 29, 2019 at 7:01 pm

    Possibly the only computer that will still be working 200 years from now provided any plastics/glues/epoxy’s used don’t degrade?
    Speaking of power consumption, I have a pair of 1024 thread Intel rack computers that consume 7.2KW each in the other room. I won’t even attempt to take a guess at how many billions of times faster than the relay computer they are, though 🙂

  10. Thees Winkler on November 29, 2019 at 7:02 pm

    The Zuse Z11 Relay Computer of the land registry in Kiel Germany was used well into the seventies. German beureaucrats don’t like change 😁it’s now displayed in the computer museum of the university of applied sciences in Kiel. The ladt time it was in operation was in 2003.

  11. Adrian Challinor on November 29, 2019 at 7:03 pm

    Very impressive. I really appreciate how you keep the memory of our computing legacy alive. This was fascinating. I remember cross bar telephone exchange being introduced in to the UK in the 70’s, about 20 years after the FACOM 128B (replacing strowger).

  12. Nitton Åttiofyra on November 29, 2019 at 7:03 pm

    I did not skip a second of the vid! Love the sound it makes while the Lights are flashing!
    The "simplicity" of old computers is wonderful I think, being able to see every part, how it works etc.
    I always go back to basics when I want to understand how computers works and seeing this on preserved and WORKING is rely awesome!
    Thanks Marc for the video and also thanks for the splendid work you and your team did restoring the AGC!

  13. Madness832 on November 29, 2019 at 7:07 pm

    Yup, that printer reminds me of the opening credits of "Desk Set!" 😀

  14. Diogo José on November 29, 2019 at 7:08 pm


  15. Russell Hltn on November 29, 2019 at 7:09 pm


  16. Dustin Sparks on November 29, 2019 at 7:16 pm

    I think this history is missing Colossus from Bletchley Park during WWII (Jan 1944), but completely classified until the 1990’s and still largely classified until about 2007. https://www.cryptomuseum.com/crypto/colossus/index.htm "The first Colossus was delivered at Bletchley Park on 18 January 1944 and broke its first message on 5 February of that year. It was succeeded by Colossus Mark II, which consisted of no less than 2400 valves." Also: http://www.rutherfordjournal.org/article030109.html

  17. Nathan McDaniel on November 29, 2019 at 7:16 pm

    I actually laughed out loud when I realized that the biquinary encoding is the same as is used on an abacus, which is (or perhaps was until surprisingly recently) very popular in Japan.

    I do have to wonder whether the technical benefit of error checking is actually the primary reason for the choice or whether it was the human factor of that familiarity.

  18. Willem Kossen on November 29, 2019 at 7:17 pm

    usually when i watch video’s with interesting tech i go ‘i want that’. and here again, i do. but my house is not big enough to fit all that and still have room for a bed.

  19. Koppa Dasao on November 29, 2019 at 7:17 pm

    Sayonara? That’s actually a bit rude…

  20. .x. on November 29, 2019 at 7:17 pm

    Holy moly indeed…
    As a child of the red LED 7 segment.
    Holey moly indeed.
    I got the Mattel little racing games and football games in the late 70s with the red dots that went bleep bleep bleep bleep bleep bleep bleep bleep.
    I got the iPhone the first day it came out.
    And I’m still amazed by the paper tape

  21. rarbi.art on November 29, 2019 at 7:19 pm

    so the japanese did spend time and money on preserving the history of their industrial legacy. Something we should definitly learn about.

  22. tignesboy on November 29, 2019 at 7:19 pm

    amazing – thank you for your very informative videos. it is always interesting to learn about computing history. that ROM implementation using punched cards and pins is ingenious,

  23. douro20 on November 29, 2019 at 7:23 pm

    One of George Stibitz’s computers was the first capable of performing operations on complex numbers and was available for use over the telephone in 1940.

    The first FANUC (Fuji Automatic Numerical Control) was also produced in 1958. Makino Milling Machine Co. was the first customer of this division.

  24. akkudakkupl on November 29, 2019 at 7:23 pm


  25. Rouverius on November 29, 2019 at 7:25 pm

    Biquinary logic looks and sounds a lot like using an abacus…

  26. Laurent Dupuis on November 29, 2019 at 7:26 pm

    So it’s a fancy telephone exchange…

  27. Chris Horry on November 29, 2019 at 7:26 pm

    Beautiful piece of machinery, thank you to the team who keeps this history alive.

  28. Andreas Huge on November 29, 2019 at 7:27 pm

    Divide by Zero!

  29. LPD on November 29, 2019 at 7:27 pm

    Absolutely loved the sound of the computer running a program. Basically an audio rendering of a Von Neumann machine. Hearing the subsystems doing their thing in concert is amazing.

  30. Nigel Oulton on November 29, 2019 at 7:28 pm

    Wow that took me back to my younger days and all the early CNC machinary I grew up with and more or less all powered by Facom. Wonderful Marc – arigatou to you and your hosts at Fujitsu.

  31. Maskddingo on November 29, 2019 at 7:29 pm

    Sorry to break the news to everyone, but I just checked Amazon, and you can’t get one of these from them 🙁

  32. Ahmet ulus on November 29, 2019 at 7:30 pm

    Gta 5 açar mı?

  33. Michael Cherry on November 29, 2019 at 7:32 pm

    18:43 "…you will be forgiven if you skip ahead 2 minutes to the end result"

    What, and miss the blinkenlights and the wonderful cacophony of relays, paper tape readers, crossbar memory and printer output? Are you MAD?! That’s why I’m here in the first place! 🙂
    20:40 Pretty sure I heard the FACOM 128B give a bit of a sigh at this point. 😉

  34. DKTAz00 on November 29, 2019 at 7:35 pm

    69 bits? nice

  35. rbmk 1000 on November 29, 2019 at 7:36 pm

    My neighbor growing up was a ww2 vet, assigned to the uss Alabama. He was a fire controlman who’s job was to opperate and maintain the fire control computers for the ships main guns. He told me that the Alabama was initially fitted with a prototype all electronic (tube based) computer. The system had to be reteofitted with an earlier style electromechanical computer due to the vibration and shock from the main guns causing the tubes to fail or vibreate from thier sockets. It seems to me they could have overcome these problems but I guess just putting in an older computer was easier.

  36. HebaruSan on November 29, 2019 at 7:36 pm

    3+3 = 1+5 confirmed

  37. Simon Østergaard on November 29, 2019 at 7:38 pm

    Super interesting. Remember reading about this machine, and the ultra nerd that restored it…

  38. Helge Frisenette on November 29, 2019 at 7:38 pm

    I guess whether a matrix manipulation took minutes or seconds was of little consequence in the early days, because it was still faster, surer and cheaper than having it done by hand.

  39. Carl Daniel on November 29, 2019 at 7:39 pm

    Awesome machine! I’m so happy to see it preserved. This really brings back two memories for me – one was visiting a working telephone switching facility in the early 1970’s. It was fascinating as a junior high school kid to watch all the relays work; to hear and see a call come in as the relays counted the dial pulses and then passed the call down through all the stages. The whole room felt almost alive as calls came in on one side of the building and flashed through the racks to the other side. The second was a project that my brother and I undertook a couple years later. Using relays that had been discarded from that same telephone switching facility as it was converted to electronic switching, we set out to build an electronic combination lock using only relays. It used a 4×5 matrix keyboard salvaged from a discarded Rockwell calculator as the input device. It took quite a few revisions to work out all the race conditions, de-bounce the keyboard, and so on, but in the end it worked and it was a fantastic learning experience.

  40. FlyMario on November 29, 2019 at 7:41 pm

    Tons of memory… Literally! 🙂

  41. Professor Penne on November 29, 2019 at 7:42 pm

    "cute yet useless robots"
    *kizuna intensifies*

  42. Marcel Huguenin on November 29, 2019 at 7:42 pm

    Thank you Marc San for this wonderful view of computer history. I enjoyed it very much. Your way of explaining is a real joy. Can’t wait for the next one!

  43. cpt nordbart on November 29, 2019 at 7:43 pm

    Wow… A flight simulator in 1958 (or a bit later) still impressive.

  44. PsychoLucario on November 29, 2019 at 7:43 pm

    in a way its a fairly power efficient computer for the time

  45. rarbi.art on November 29, 2019 at 7:46 pm

    16:53 Again those japanese dates, which count in the years of their respective majesty, so probably Shōwa 34.

  46. no middle ground on November 29, 2019 at 7:49 pm

    THANKS!! THIS AS ALWAYS…((this was cool))

  47. Gus F on November 29, 2019 at 7:49 pm

    I wonder if the early users, or even the current maintainers of this machine could realize a bug in the program if the rhythm of the machine is wrong.

  48. Gustavo Coelho on November 29, 2019 at 7:50 pm

    It takes sqrt(2) seconds to calculate sqrt(2)…

  49. Vampira on November 29, 2019 at 7:50 pm

    For some reason i draw some paralells here to aincient Japanese carpentry design and thinking, but that’s a sign of true ingenious to posess the ability to taking in elements from very different and sometimes unexpected things and use them for new inventions.

  50. rapsod1911 on November 29, 2019 at 7:50 pm

    Sounds that printer made are amazing.