Exploring SKALA: Chernobyl Reactor Control Computer 

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The computer resource limitations you discussed are not only in the Chernobyl Skala system but also in the USA 3 mile island reactor installation. It was noted that the priority data output from the computer was lagging very far behind during the melt down emergency. I am thankful for the chance to see this equipment which may have been lost to the scrap yard without your intervention.

all these hand-soldered elements, the ton of wire-wrapping and these wonderful ferrite-core memory-elements. The amount of work that must have gone into this system is staggering.

This is a viral historical treasure to preserve as much as possible.

This video is amazing and deserves a million views🎉

This is insanely cool, thank you. Even with my understanding of computers and programming it still blows my mind that people figured all of this out with the limited technology they had. Both hardware and software.

It's incredible how modern computers barely take up space, but 37 years ago they took up an entire room! SKALA was very powerful for It's time!

Wow, that system has a strong creepy vibe to it (in a good way). The control rooms were part of the computers. The operators were integral parts of the system, enclosed within it, their minds filled with codes. It must have been an overwhelming experience.

Well done! I have an affinity for old computers, when I was in the US Navy aboard the USS Jason AR8 (a repair ship) circa 1974 I was responsible for operating a Univac AN/UYK 5V computer, used primarily for tracking parts and work hours. Not a single IC anywhere, everything was transistor/diode logic, with about 4096 18-words of ferrite core memory. I/O was four tape drives, a teletype for a console, a huge chain driven printer, and an even bigger card reader/punch. Surprisingly, the system had a COBOL compiler, and I wrote a small program to accept punch cards and print out a list of everyone serving aboard.

You can't imagine how long i've been waiting for any sort of documentary on SKALA. Thank you!

I’ve been following the Chernobyl for disaster for years. Thank you for giving me more insight on how this system and how everything works. Always has been a curious fascination. I’m glad I found this channel.❤

This is brilliant; one of the most captivating documentaries I've seen in a while. Superb use of archive photography, and great to see such effort put into the illustrations. And thank you for going into such detail on the various processes and conventions involved.

Thank you so much for this video. My mind is absolutely melted. I am a Sysadmin, and the tech back then was insane! I cannot imagine the amount of engineering that had to go into this.

You're going full-on CuriousMarc here! What a magnificent system and video. And the comparison with the AGC DSKY is on spot here. Same thought crossed my mind. Speaking of the DSKY... just look at all these electroluminescent displays - another feature these systems had in common.

My wife grew up in Slavutych. Her mom was one of those engineers at Chornobyl, but she got there in 1988; 2 years after the accident. She worked with the remaining operational reactors (obviously). I myself am OBSESSED with retro computing such as this, and especially the reactor computers of the era. I'm dying to create my own replica reactor control room... Edit: if it wasn't clear, this video is AWESOME. MASSIVE thank you for this!!!

Thanks for your dedication and work in sharing this precious information with the world! Greetings from Brazil.

Hello from Australia. Thank you for the time and hard work you put into this, it was extremely interesting and I'm looking forward to more. Best regards.

Great video! I was searching for info about SKALA for years. Here in france, Tchernobyl was a tragedy that marked everybody. The RBMK reactors are prety well known and understood but cold war, USSR computers remain misterious. I went to the science museum in London ans they a stunning BESMM6, impressive machine for sure.

Amazing view of the system and thank you for saving and explaining it. The disaster is an incredibly personal story for many that the hardware and software underlying it all is often overlooked. Looking forward for more on this!

Great video! Also: SKALA was not based on ES EVM (soviet copy of IBM 360), this was not typical of soviet computer systems of that time. Also turns out that you absolutely needed this computer system for normal operation of the RBMK reactor, as RBMK had an unusually large positive void coefficient. RBMK doesn't keep water inside the reactor under pressure, now you end up with fewer water within the reactor, as the water evaporates. This creates temporary voids. Now water is also a neutron absorber, so that these voids are resulting in a stronger chain reaction and increasing the thermal output. Eventually the whole thing exploded... The book "Midnight in Chernobyl" by Adam Higginbotham mentions an accident at the first installation of the RBMK reactor in Leningrad: "On the night of November 30, 1975, just over a year after it had first reached full operating capacity, Unit One of the Leningrad nuclear power plant was being brought back online after scheduled maintenance when it began to run out of control. The AZ-5 emergency protection system was tripped, but before the chain reaction could be stopped, a partial meltdown occurred, destroying or damaging thirty-two fuel assemblies and releasing radiation into the atmosphere over the Gulf of Finland. It was the first major accident involving an RBMK reactor, and the Ministry of Medium Machine Building set up a commission to investigate what had gone wrong. Afterward, the official line was that a manufacturing defect had led to the destruction of a single fuel channel. But the commission knew otherwise: the accident was the result of the design faults inherent in the reactor and caused by an uncontrollable increase in the steam void coefficient. Sredmash suppressed the commission’s findings and covered up the accident. The operators of other RBMK plants were never informed of its true causes. Nevertheless, the commission made several important recommendations, to be applied to all RBMK-1000 reactors: develop new safety regulations to protect them in the event of coolant loss; analyze what would happen in the event of a sharp rise in steam in the core; and devise a faster-acting emergency protection system. Despite their apparent urgency, the reactor designers failed to act on a single one of these directives, and Moscow promptly ordered more of the reactors to be built. The day after the Leningrad meltdown, the Soviet Union’s Council of Ministers gave its final approval to construct a second pair of RBMK-1000 units in Chernobyl, expanding the station’s projected output to an impressive 4,000 megawatts" Interesting if SKALA was supposed to have fixed these inherent instabilities during low power loads, but no - it was only a monitoring and recommendation system that was not designed to control the reactor directly.

Excellent move stepping in to save the system. Every person has the power to do something when they notice a bad decision is about to be made.

That array of analogue gauges is extraordinary. Thanks for showing us Alex, this is a fabulous documentary, so fascinating and just brilliantly presented. Thanks to both of you for all the effort you put into this channel.

This is beyond cool, always wondered what computer system was behind chernobyl. Will there be any chance that the Tapes and drives that still exist to be read it and archived? Maybe some day the SKALA architecture / system can be reverse engineered and be emulated with the original software Proud to be a patreon member for this channel

After many questions received, we will make a series of Patreon posts with more details and bonus materials about SKALA and control room systems - you are welcome to join us! Link is in the description of the video.

This video HAS to blow up. The immense amount of knowledge, research, and incredible amount of skill to apply here has absolutely paid off. This is HISTORY you're making, man!! You earned another subscription! 😄👍❤️🇺🇦

I remember reading about SKALA a few years ago (when my chernobyl obssesion). I was bummed by the low amount of information about the computer. This video really made my day if not my week.

This is really interesting! So SKALA was much more than a computer solving complex reactivity equations but also an enormous real-time data acquisition system too - measuring and logging everything as well as looking for anomalies from "normal" operations?

Thank you so much for making this video! For decades I ran in to the same issue that you did, no resources I could find ever described the SKALA system at all; documenting industrial control systems like this is very important to retro computing history and is a very overlooked sector for computer historians!

This was really fascinating and well made. I hope that lots of other people get to see your work.

Дякую за це фантастичне відео. Я був зачарований Чорнобилем з часів катастрофи, яка сталася, коли мені було 16 років, і здачі важливих іспитів. Я знав, що радіація досягла моєї країни, і що чудове весняне повітря, яким я дихав, також було (трохи) радіоактивним. I am from the UK, and have always wanted to visit the reactor, Pripyat, and the DUGA installation, but im disabled now, and I dont think I could handle all the walking!! I send you Blessings and Love from the Northern UK, to you and your family. Stay safe!. Slava Ukraine! 🇺🇦 ❤️

History should never be forgotten. Saw this on YT main page recommends . Well done !

I’ve watched hundreds of videos on Chernobyl and never heard of this. Great job very informative

I wish I could give 100 likes. It was so touching to hear about Mrs. Pripyat feelings. You impress me in keeping on making good videos like this during more conflict. Ukrainian people must be very tough. Your people have overcome so much in the past 100 years.

Fascinating. I never really looked much into this and didn't expect that they actually had such a complex DAQ and control system. I thought this was all done by hand with manual gauges and some discrete analog electronics.

Thank you for commissioning and documenting this for us. Seems very well sculpted for an early age computer!

I am an electronics engineer and it was very interesting to learn about this control and data processing system. There is nothing on the Russian-language RU-vid about this system. Yes. You're right. Regarding the fact that the parameter time was output to the printer after processing. In one of the videos I heard from one of the panel board engineers, the time of changing the parameter and its subsequent indication.......... I was shocked...... 18 seconds!!!!!! So, really, the processing time after receiving the change signal and its indication (printing) is huge. 18 seconds is an eternity for a reactor.

Superb production, very interesting and informative!

Excellent video! I was always interested in SKALA and how it worked. Thanks for the video! :)

First video I've seen of yours. This was absolutely mind blowing. Thank you. I would love more on these details you eluded to.very well done and nicely paced with great footage and explanations

Great video. This computer was amazing, it reminded me when I flew the Embraer 190 where everything is also controlled by the computers, with self tests, failure detection, dual channels that switch automatically. All you have in the cockpit is a digital interface.

12:37 - I have built a clock from the same VFD displays as were in the panel in SKALA, nice to know that the same parts were used in chenobyl. VFD is IV-22. In my language skala means rock.

It's so cool they decided to save it. I've always wanted an explanation of infrastructure like this because most of it is very vague and doesn't get into how it really works. This video deserves so many more views!!

Thanks! I've been waiting for a detailed video about the Skala computer for years. I hope in the future you make more videos about Skala and also the other less known auxiliary systems of the NPP.

I recently stumbled onto this channel and can only say it is AMAZING! Thank you for making these videos!

Really great work , looking forward for other videos. Many thanks. Sveiciens no Latvijas 🇱🇻

I had no idea that I needed this in my life, but now I'm hooked! Super interesting information, and very well put together, thank you for making this (and saving the computer).

Great Video ! I was asking Russian friends for years to do this, but everyone did say, then i will be arrested as a spy. But there are people that did restore the SKALA systems, and specially the SKALA at Chernobyl ! Great uploads.

Thanks for the making of this video: it is incredibly interesting. Also, discovering, analizing and showing pics and video from that time demands a lot of time and work. Again, thank you very much for doing this!

Greetings from Romania, amazing video, you pieced together so much info about this system… great work, we’re all grateful. Thank you!

Thanks for the detailed and considered look at the RBMK control system. Plus all the work that you have put in. All the best with your future projects :).

The most amazing RU-vid video I have seen in a very long time. A fantastic find and definitely something that needs to be stored for eternity - and your explanations just gave me so much new information about Chernobyl. keep up the great work.

Большое тебе спасибо за сохранение ценной информации и интересную подачу!

The teletype segment sounded so incredibly rhythmic and musical

"Skala" (plural: "Skaly" - stress on A)means more in Russian than "rock". Original semantics of the word aside modern use specifically denotes the upper part of tall mountains that is bare rock. The word is never used to refer to individual rocks, for example - a boulder that needs to be moved when clearing a road or a rock you could pick up with your hands. The word's frequent poetic use is possibly the main reason why they decided to stick with that abbreviation. I can see that NASA's taste for abbreviations was certainly shared by the Soviet programmers. This is certainly a very unusual, high value educational video. I thought SKALA was forever lost to history by now. My first ambient music track "Deus Ex Machina" was dedicated to this ancient apparatus ☺The scifi part of me envisions a future museum of computers where all of world's important and iconic historical computers, with "Enigma" and Turing's computer which cracked it, Apollo's computers, 1980-s Soviet ЭВМ and so on. And of course, - this amazing beast.

I has been waiting a video like this. Thanks

This video is perhaps one of the greatest documenting videos I've seen on old computers! I genuinely loved every single moment; congratulations for such a beautiful production!

As a former instrumentation engineer at a ASEA ATOM BWR reactor this is impressing as hell! Especially if you think about that the computer must handle over 1600 analog channels at the same time (probably even more if you count in such parameters like steam and feedwater temperatures, steam pressure, feedwater flow and probably some data from the turbine). And then I haven't even mentioned that RBMK reactors have that possitive feedback loops which means that the control rods must be actively controlled all the same time in order for the reactor to maintain a consistent power level.

Thank you guys, incredible stuff, such rare info. Had no clue, why there such small number of subscribers on this channel. Thank you for so detailed review of many types of equipment. Truly rare things you have access to. I`ll use some references from cannel, for props modelling, in future METRO game series. Greetings from Kyiv.

Man. What a gem! Greetings from the other part of the world. This is amazing. What a nice retrocomputer dive into how the USSR created their first main frames and control systems.

What a FASCINATING video! This is an area of the subject that really doesn't get the attention it deserves. You explain it well for an old tart like me who doesn't really understand computers. However, when you mentioned the request system I also started thinking about Apollo. I do hope you do more of these. Thanks for sharing your hard work!

Very intresting video complexity computer systems :)

Good job again Alex.Some people thinks that USSR computers were piece of crap, but in fakt they were working well and reliable for their purpose. Thank You for all Your reviews

This is such a niche interest for so many people, and you just filled a void of knowledge that I didn't even know I had. Thank you for these videos, amazing graphics and explanations!

Great video. I work with modern marine automation systems as part of my job. I've always had a fascination with the SKALA system since learning of its existence, but there was almost no information out there about it, how it worked, or how extensive it was. Considering how far Soviet computing technology lagged behind the west, this was a surprisingly capable and extensive system that monitored probably thousands of data points with relatively little computing power. It's also cool to see some things that haven't changed all that much - e.g. the operator station at 11:40 for reading automation tag values is a concept that really hasn't changed. Great job in documenting and helping to save an interesting piece of computing and industrial automation history

Awesome video! Love to see how these old machines worked. The complexity is mind boggling. Thank you for making this and your hard work to research it.

I also read almost anything what i could find avout chernobyl disaster. And cannot find any info about skala system in english speaking intetnet. Thanks a lot for this excellent presentation

Thank you and your associates so much ! I have been waiting for this video , this documentation of this computer mainframe for a very , very long time ! Bravo ! Simply Bravo !

Hi, really great video! Thanks for sharing with us this unique and rare informations. I would like to see continuation about this topic :)

Another amazing video from you. It is great as a piece of Chornobyl history, and also as computer history.

Magnificent video for the tech geek community. Mad respect for the scientists and engineer that created these machines in those old days.

WOW Amazing I am gobsmacked that something that complicated could actually work and work well.

Very cool video, it's obvious that a great deal of research went into this. Well done.

So they were essentially dual-core, each core having 20K cache and 8K shared RAM, with ECC? Controlling VMs via machine code, with hand-punched, punch-tape BIOS? These computers may be light-years behind modern specs and functionality, but way ahead of modern computers in charisma.

Thank you so much for this in depth info on this beautiful computer. Just love those old proprietary computers :)

To an old, ex-mainframe operator ths is pure gold - thank you!

Great Video, the sheer engineering that went into this is amazing, especially the monitoring system.

I'd be cool to have a dump of all the alarm sounds and such, it's hard to find but honestly I find them cool. I'm kinda building a game around managing a reactor and this stuff always inspires me

Very interesting. I worked in US BWRs from the mid 80's. They had data gathering systems that tracked the power levels throughout the core. Like the RBMK, during refueling individual bundles were shuffled based on their previous exposure 'burn up'. Before this time, some plants just recorded the data on tapes and sent them to a vendor that would read/ analyze and project future thermal performance and 'fuel shuffles'. Yeah, those old 'band printers' were not particularly fast. Ours were 300 lpm (lines per minute) but the alarm typer was a simple dot matrix that was much slower.

Really amazing work ! Thank you for all ! SKALA design is very elegant :) Best greets from France

Excellent video.Very many thanks for posting this.

Amazing content. Thank you very much for this unique and almost forgotten story. For me as a computer engineer it is mind blowing what they did with available computer hardware back then. The Chernobyl story is engraved in our collective memory, we'll never forget.

I think this is the first video of yours which I've seen. Bravo! There's a ton of stuff about computers that I don't understand, but this is fascinating nonetheless! My friend has been educating me about Unit 4, and I have to say, it's very interesting!

Brilliant! Thanks so much for making this!

Thank you for this fascinating insight into the control systems of the reactors! As a computer enthusiast and professional since the early 80s, and with an interest in the history of computers, this was right up my street - subscribed 👍

Wonderful video! Thank you very much. I've been waiting for it for a long time. 20K RAM, no CRT no keyboard, writing programs in machine language. That’s it. That's what real men do.

Very cool documentary. Thanks a lot. Maybe you could think about a part 2 including more info about the H/W architecture of the SKALA and its monitor/OS. You made a comparison with the AGC. Did the SKALA also have a prioritization of tasks like the AGC did? Some remarks you made that measurements might be delayed waiting for a "processor window" seem to indicate that it did. How exactly did this task scheduler work?

Indeed very interesting video. Thanks for your work ! Deserves much bigger exposure

this is an enjoyable and informative video, i enjoyed watching it. imagine all of that work they put into making skala could have been destroyed and never seen again if you hadn't stopped them

Hello! I would really like a more detailed summary of the SKALA system, looking at the implementation of the connections, the communication between the individual units, and the software implementation. Go to these, or to any of them :) I really liked your video, thank you!

Very impressive technology for such a long time ago!

Amazing work as usual, this is the video that deserves 2 million views!

This video is awesome and very informative. I really appreciate the time you took to make this as easy understandable as possible about a so complex subject. You earned a subscriber. Keep up the good work!

Wolderful. Thanks for a great video !! I whish there were english documentation of skala Computer manuals and architecture so it can subsequently be emulated on an an FPGA !! Cheers

I remember the Barsebäck NPP having a teletype based backup system back in the 80's when I interned there. Nothing as cool as the C64 I had at home :P

You have to agree that people use to be way smarter and with deeper knowledge of processes and hardware, that was required due to fast response in a situation, if needed. Today we are building anti-stupid protection everywhere, to limit human error. Other than that, amazing video, keep up the good work !!

Absolutely stunning. Thank you for helping save this piece of history.

Great video. Thank you

Very very cool, amazing how much space these things used to take up

Great video! Great visuals, explanations, added graphics too. Looking forward to seeing your next one!

Been waiting for this video... And you did not disappoint! Excellent!