Why Build Colossus? (Bill Tutte) - Computerphile
Why Build Colossus Bill Tutte Computerphile

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Cracking the code was only half the battle. To keep the upper hand, when using Bill Tutte's statistical methods, the detailed counting had to be automated - enter Colossus! Professor Brailsford takes up the story. The professor's notes: http://www.eprg.org/computerphile/lorenz-combined.pdf Bletchley Park Playlist: https://www.youtube.com/playlist?list=PLzH6n4zXuckrSWWIDJ_3To7ro5-naSk8v Professor Brailsford used the book "Colossus" by B. Jack Copeland and others (Oxford University Press, 2006). Also recommended are chapters 18 and 19 from : "The Bletchley Park Codebreakers" by R. Erskine and M. Smith (eds.) Biteback Publishing 2011 https://www.facebook.com/computerphile https://twitter.com/computer_phile This video was filmed and edited by Sean Riley. Computer Science at the University of Nottingham: https://bit.ly/nottscomputer Computerphile is a sister project to Brady Haran's Numberphile. More at http://www.bradyharan.com

Comments

Daporan : Professor Brailsford is the boss!

LetsDoRedstone : I love all the videos with professor Brailsford!

Man from Mars : Look how times have changed: from "Never turn off the computer" to "Have you tried turning it off and on again?"

M A : Such an interesting topic and such a calm and intelligent man

Nathan : Imagine the change that would have happened if someone took a simple Raspberry Pi back in time to the scientists/arithmeticians working on this stuff.

Kizmet Mars : Because building Colossus increases trade?

Neil Roy : I always love listening to him, doesn't matter what the topic is. Such a treasure.

B3ll3r0ph0nt3s : Professor Brailsford is a pleasure to listen to. Please give us more! =)

Martijn Heeroma : Thanks again Professor Brailsford

Haze H : well they shut down hydra bane all-ins pretty effectively I believe.

artemonstrick : I can listen to this guy forever

Micai Askauss : I like this guy

Mouse-Floof : heh, I have something to attest to the power of tubes being gently heated and kept at slow-ish smoulder... The Hammond Novachord :3

Ben786 : I've just realized why I love hearing Professor Brailsford speak — he sounds just like Winnie the Pooh!

TheBigFat : You shouldn't, they get easily countered by the zerg's corruptors.

rchandraonline : This is one thing assembly language programmers usually learn. Back in the 8 bit microprocessor days, you used to look at how many bytes an immediate load used to take, like LD A, 0 on the Z80, and how long it took to execute, and compare that with a similar operation like XOR A, A, a lot of times it took less time (clock cycles) or less space or both to do the XOR. As long as you knew this as an idiom, or made code comments, it didn't reduce readability/intelligibility.

Steve Evans : Legend... And Tommy Flowers, being a practical man, not just theoretical, was spot on... Valve last for years if you just leave them running.

Jiyva : could just have droped the double leters in their mesages

nab 6215 : I love the WWII and code breaker talk. Please keep him talking about this.

alex jervis : My uncle worked at Dollis Hill, with Tommy Flowers. He never spoke of his work. (Wretched man!)

Naughty Robot : Did you never even see The Forbin Project, you fools? You've killed us all

Gale Aeras : Because they are good against light units

Rohan Dvivedi : I Love all of computerphile videos

EddyGurge : I love listening to him.

S0chan : That's NUMBERWANG!

Peter Frencken : When i was an industrial electrician in a factory that ran 24/7 365 days a year, we used to hate shutting down equipment for maintenace. There was about a 50/50 chance that one of the electromechanical parts in the system would fail on startup.

AustrianAnarchy : Dr. Forbin's answer was quite sufficient, thankyouverymuch.

Julian Weinert : Wow. I mean they could've simply prohibited double characters. You would be able to properly understand the whole message once decrypted but would get rid of this weakness by the cost of an order...

Mob Mentality : would the Germans have known character doubling was an inherent flaw in encryption? perhaps a "drop one letter from all double letter words" directive should have been implemented!

Literally God : Absolute legend

ThePharphis : This is similar to X-Ray sources for crystallography (Cu, Mo, etc.) There is a working-voltage and a standby-voltage and these instruments (to be used by researchers) is only to be turned off for maintenance or long pauses in work schedules

Yaddlezap : If only the Germans had been broadcasting in lipograms excluding double letters, lol.

A Lee Wade : Awesome video as always. From the video, "Tommy said to them, I've been doing research on use of thermionic valves in telephone exchanges..." Valves had been used for since 1915 to amplify long distance calls. The genius of Tommy Flowers was his research into _switching_ calls electronically. He was way ahead of his time... and sadly under-recognized for his contributions.

Stay EZ My Friends : Wow, I know a lot about ww2 but I was oblivious about this machine and it's counterpart it was built to crack. Thanks for the upload.

Dave L : Is there anything better than a Brailsford video?

Jeongheon Lee : I could never wrap my head around that code could be cracked by statistics. but now i can thanks to him!

11Kralle : We should never have insisted on 'stickstofffreie Schifffahrtsspeziallagerrechte'!

Ronny-san : It is really funny that I saw the your Enigma Videos about a year ago, decided to make it the topic of my seminar paper (the exact Topic is 'deciphering machines at Bletchley park') and just when i came to the chapter about the Tunny and Colossus I found this video uploaded not long ago xD

Hrnek Bezucha : For our yank friends, thermionic valve is a vacuum tube.

Keex11 : Why? To play Numberwang, of course.

Zadster : Interestingly, in all the books I have read about Alan Turing, Bletchley Park and so on, there is very little connection mentioned between Alan Turing and Tommy Flowers, and I believe Turing had long moved on to Hanslope Park (early 1943) to work on voice encryption by the time Colossus actually became "Turing Complete" and properly programmable with decision branches and loops. So we end up with the man who defined what a computer is, and the "first" (yes, Konrad Zuse etc, I know) programmable electronic computer in the same place, but with seemingly no link between them.

Christopher Lee : Please interview Brailsford on Apple. Just want to hear his thoughts. Leaving this comment here, barrel completely unloaded. You know it's the right thing to do.

Daniel Jensen : I wonder what the clock speed was for that thing. A few Hertz? 100?

MaxSantos : What? So if they "transmited" the "mesage" with purpose "mispeling" by removing the double chars... the "mesage" would be readable but not crackable?

MaxSantos : And now... you could probably do it in a crappy Arduino, let alone a Raspberry!

Tyler Costantini : I use valves (tubes in my case) all the time. They are still quite common in medium to high power transmitters. The same holds true, we like to bring the filament up slowly using a variac or even a built in so called soft start circuit. They are highly reliable if treated properly and can be abused much more so then transistors in similar applications. As the old saying goes a MOSFET is one cycle from exploding at all times! Don’t get me wrong I don’t want to go back but it amazes me how fragile people thought tubes could be and my experience is exactly the opposite

Lordious : Pizza! 2 Z

Chel Viz : So how did they go about estimating which letter the exclusive ORs represented? A neophyte here, thanks a lot!

Youthure : Interesting!