Von Neumann Architecture - Computerphile

professor Brailsford a lot of people talk about von Neumann architecture and we've talked about Babbage we've talked about chewing who was von Neumann we've done a lot about chewing we've done a fair bit about Babbage in the generation earlier in fact a lot of people I guess in the english-speaking world would regard Turing in some way as being the father of computing it came up with this very important result in the mid thirties about what was computable and as we now know he to his credit it wasn't at all afraid to burn himself at soldering iron and try to create hardware which he did at Bletchley Park during the war so yes if he's the father if Babbage was the grandfather and if a the Countess of Lovelace was the great-aunt then who on earth was John von Neumann and why is he mentioned alongside during well right early-out so let's say John von Neumann was the impossibly talented impossibly charismatic very wealthy uncle to computing it was he that in the mid 1940s in a way made it all happen by the force of his own personality and kept it not just in an enclosed community but encouraged all those who wanted to build general-purpose computers to come along to this summer school and do it but that really I guess is in the future it's where we've got to get to in the von Neumann story but yes you're quite right Shawn to say that one of the first phrases that almost any computer scientist hears about is the von Neumann architecture for computers which to a large extent we still follow even now all of 160 50 years later so we've mentioned dead sack before we'll be coming back to mention this very important early computer again but it is a von Neumann machine and all it's saying is it's very simple to build a computer you need a store or memory as it's more commonly called nowadays to hold your instructions and your data you need a control unit often called a CPU now and you need an arithmetic capability the ALU the arithmetic and logic unit again many of you will know in modern chips those two are often combined into what we just call the CPU chip nowadays and you need input devices of various sorts leading back to people's telly types input/output devices for backup storage disk and so on you need to be able to do input and output so there it is it's just one two three four five boxes that is the von Neumann architecture and it's very very similar today there was a big debate at the time about that store that memory shouldn't you for safety's sake put the instructions of your program in a different sort of memory to your data wouldn't it be safer to do that and better in some ways on the other hand clearly if you've got a good memory technology that works the temptation might be just to put them in separate areas of that same technology and try and take some sort of precaution about them not interfering with each other in edsac the only way to get into a subroutine and get back out of it again was to override part of your program instructions let's just return back to this incredible character john von neumann how does he fit in alongside Alan Turing well like I said he's the older impossibly talented uncle did cheering of von Neumann know each other oh yes they did they were both basically trained as mathematicians mano a man it's hard to know where to begin and where to end you can't exaggerate enough about how good he was he was Hungarian and his Hungarian name where they give surnames first was I think no mananas his father was very very wealthy and when one was quite young the family became ennobled in Hungary became basically at the level of Baron hereditary Baron I think over here Jana was very talented he was a childhood prodigy he could divide one eight digit number by another eight digit number in a fraction of a second when he was aged about 6 he loved history he was a multi-talented polymath he easily came top of the class he effortlessly took in detail and that's the first thing that all of his mathematics contemporaries said about him was his sheer speed of picking up new ideas and seeing the ramifications of them so he was notorious even as a teenager and as a maths undergrad he did his early education I think up to PhD level in Budapest he almost naturally ended up at a place we mentioned before in connection with girdle and Hilbert I'm talking of course about getting an University in Germany so Norman janosh makes the journey via a PhD to becoming effectively the research assistant so the superstar David Hilbert at gutting them but because his family being a noble's he's not Janish Norman any more known in Janos sorry he's johann von Neumann impossibly talented Hilbert his supervisor at a seminar given by by Johnny John Johan asked who his tailor was because he's impossibly smart pinstripe suit was just a complete knockout so he was a legend almost the moment he got there and did some fabulously important work there it was obvious that for somebody of his talents he was going to get a full professorship very quickly indeed I think it became impatient waiting for it to happen at any German university so in the late thirties 37 38 somewhere around there anyway he got an offer from Princeton in New Jersey and that was I don't know very timely it's all fitted in together very well as part of his tours of Europe giving seminars and on his way to Princeton I think he met churring in the mid thirties in Cambridge because he gave seminars there and I think a lot of mutual respect grew up I mean obviously curing being in or von neumann wouldn't be so exceptional but after that 1936 paper of Turing's about decidability following on from girdle and all that von Neumann rated Turing there was no question of how that this was evidenced by the fact you will recall those of you seen my previous videos that Turing also took a sabbatical and worked with Alonzo Church at Princeton well von Neumann was there by that time one was such a superstar they not only made him professor and mathematics of Princeton at an absurdly early age probably about 30 something like that but some of you were recalled right next door to Princeton about a mile and a half across the meadows is the Institute for Advanced Studies which have been endowed in the early 1930s by a multi-millionaire and this really was the ultimate Club to be invited to join you've got to be of the quality of Einstein who accepted the invitation Hermann vile one of the founders of quantum mechanics girdle we know about girdle girdle was invited to just come to IAS Institute of immense visit princess stay as long as you like yes you're a professor everything found food accommodation a lot all we want is to have the greatest minds here von Neumann was offered a professorship in that community I think at age 35 maybe slightly younger unbelievably young he'd hardly been a prince in a year or two as an ordinary mathematics professor everybody thought this is a truly phenomenal person he reminded many people of absolute superstars like Newton Gauss Euler Einstein Hilbert himself even that me early to mid thirties they could see that potential in him there so yes Turing visits Princeton in 1938 worked with Alonzo Church but also of course had frequent interactions monoi man and then came the big question if you recall for Alan Turing should I return to England and do my patriotic duty according to Andrew Hodges definitive biography of chirring chirring father was all for curing staying in Princeton you know keep out the war gets a prestigious mathematic job and that was underlined by the fact that von neumann offered during a job he basically said Turing would you like to be my research assistant at the Institute for Advanced Studies now tareka see straightaway that just would just make you as a mathematician you were invited by the great Fontenoy Minh to be his research assistant is only problem was I think first of all I think Alan Turing did feel a certain patriotism in wanting to come home and do his bit there was also the worry if there's at that time von Norman had not properly got into computing he'd not turned his considerable talents to considering it and for the research assistantship he wanted Alan Turing to do quantum mechanics another of von neumann's great love and I don't think cheering was keen on that because he knew from experience at Cambridge where he'd tried doing mathematical physics it really wasn't his arena at all so he politely declined with great things came back to England and the rest if you like is more or less history now there's Johnny as he'd now become johann von Neumann speaker of four five languages including Italian and English once he'd transferred from getting on to Princeton wanted to become the all-american genius so he was in a more formal occasions he was just John von Neumann but to his friends he was Johnny I you counties graduates enough I mean his wife said he can count everything but calories he was fond of food and drink the champagne parties the glitz the glamour the girlfriends good old Johnny he absolutely was the antithesis of the Shire mathematician he was all encompassing and everyone who met him was just by how he could see his way through problems in no time flat and just do impossible things and so he was there in a very very nice position Institute for Advanced Studies even before the Americans joined the war but he stayed there throughout the war but being who he was he was endlessly in demand to be a consultant and most famously along with people like J robert Oppenheimer he was one of the consultants employed on the Manhattan Project the atomic bomb in the hydrogen bomb but he was used by the army the US Navy the Air Force everybody wanted Johnny as their consultant and this even included as the war developed the facts that one of the earliest computers which we have mentioned in a previous video was University of Pennsylvania Moore School of Engineering they helped develop the ENIAC which if you remember was a vacuum tube computer running on decimal arithmetic and initially devoted to gunnery trajectory calculations it was a bit late in 1946 to be indirect strategic using gunnery actually Johnny who by this time of course was a consultant to the Moore School devised a way I think to turn any akin to being a general purpose computer although it wasn't a very efficient one and I believe he used it for some calculations relevant to the atomic bomb and all that kind of thing the natural question arising with everybody at the end of the war went like this we all know or even though it's top-secret at Bletchley Park we have heard gentle rumors that computers are being developed all over the place and you've always got to say are they special-purpose how they general-purpose are they binary are they decimal are they fully electronic or are they electromechanical and literally there must have been at least a dozen machines around that satisfied some of these criteria if you ask Germans about who's the father computing they say konrad zuse a-- he developed electromechanical machines look what you're incomplete and calculated things but they never got beyond electromechanical you get on to electronic ones you get at enough some fun berries electronic valve driven thing special purpose though could solve certain differential equations and even Tommy flowers and Colossus we know special purpose can decrypt any traffic Lawrence cipher has it later become known as so you've got everything happening that if it's general-purpose it's not yet electronic if it's special-purpose it is electronic but we want it to be general-purpose so at the end of the war was the perfect time to get everybody together and say look now that the war's over we all want to find the way to do it correctly to build general-purpose probably binary base because they're more reliable all electronic digital computers how do we do it and who better to lead the charge and run a summer school and be associated with it then uncle Johnny of course and the more school at Pennsylvania to their great credit did this they decided that the successor to ENIAC would be a thing called Edie vac they said yeah it's gonna take us three or four years to do this but in the meantime here we are 1946 why not all of you all over the world who are interested in the quest to build general-purpose all electronic digital computers probably based on the binary system will hold a summer school in the Moore School of Engineering 1946 welcome everybody did cheering go to it he was I believe in that time of a National Physical Laboratory in the UK no he didn't hated conferences did cheering he wasn't a club herbal character couldn't stand small talk classic shy mathematician not at all live on ointment right so Turing wasn't if you like the UK representative there and one wonders whether he would also been held about by Bletchley Park and the Official Secrets Act course he'd only just left a few years before the representative from the UK was somebody who was Turing's a Zach contemporary they had both done mathematics in the early 1930s at Cambridge they had both got first-class degrees did they get on not very well but who's this other person his name is maurice wilkes Morris Vincent Wilkes and by the vagaries of job allocations around about World War two he didn't end up at Bletchley Park did Morris he ended up in radar but he knew enough about mathematics and electronics to be in a good position to do I'll make a von Neumann machine in the UK in the period from about 1946 onwards but we better stop there because Morris and his edsac is an extra story and this depends on the value being fetched from there and I'm just going to show this as an arrow here but the next instruction load r2 from a see why doesn't depend on anything

Channel: Computerphile

Views: 522,972

Keywords: computers, computerphile, computer, science, Computer Science, University of Nottingham, Professor Brailsford, John Von Neumann, Von Neumann Architecture, EDSAC, ENIAC, EDVAC, Moore School, Princeton, IAS

Id: Ml3-kVYLNr8

Length: 16min 20sec (980 seconds)

Published: Tue Feb 13 2018