>> Sean: Professor Brailsford - a lot of people talk about von Neumann architecture and
we've talked about Babbage; we've talked about Turing. Who was von Neumann ?!
>> DFB: We've done a lot about Turing; 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. He came up
with this very important result, in the mid-thirties, about what was computable,
and as we now know. to his credit. he wasn't at all afraid to burn himself with a
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 Ada,
Countess of Lovelace, was the Great-Aunt,
then who on earth was John von Neumann? And why is he mentioned alongside Turing?
Well right at the outset 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 Sean, 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, what 60-70 years later. So, we've mentioned EDSAC 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 [that] 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 Teletypes [with]
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 [instructions and data] 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 over-write 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
Turing and von Neumann know each other? Oh yes they did! They were both, basically,
trained as mathematicians. Von Neumann - 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, Neumann Janos. His father was very, very wealthy and
when one was quite young the family became ennobled in Hungary. [They] became
basically at the level of Baron - hereditary Baron I think
over here. Janos 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 Godel and Hilbert.
I'm talking, of course, about Gottingen University in Germany. So Neumann Janos
makes the journey, via a PhD, to becoming effectively the research assistant
to the superstar David Hilbert at Gottingen. But because his family
had been ennobled he's not Janos Neumann any more - Neumann
Janos sorry - he's Johann von Neumann - impossibly talented. Hilbert his
supervisor, at a seminar given by Johnny,
John, Johann (!) asked who his tailor was. Because his 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 he became impatient, waiting for it to happen at
any German university. So, in the late thirties - '37-'38? Somewhere around there anyway -
Anyway he got an offer from Princeton, in New Jersey. And that was, I don't know,
very timely. It 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 Turing in the
mid-thirties in Cambridge. Because he gave seminars there
and I think a lot of mutual respect grew up. I mean, obviously, Turing being in awe of
von Neumann wouldn't be so exceptional. But after that 1936 paper of Turing's,
about decidability, following on from Godel and all that, von Neumann rated
Turing - there was no question about that. This was evidenced by the fact, you will
recall - those of you who have 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. Von Neumann was such a superstar, they not only
made him [full] Professor of Mathematics at Princeton, at an absurdly early age -
probably about 30, something like that. But some of you will recall, right next
door to Princeton - about a mile and a half across the meadows - is the Institute
for Advanced Study which had 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 Weyl one of the founders of quantum mechanics; Godel - we know about
Godel. Godel was invited to just come to IAS - Institute for Advanced Study at
Princeton - stay as long as you like. Yes, you're a Professor; everything found: food
accommodation; the 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 at Princeton 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 at 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 at seminars with von Neumann 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 Turing,
Turing's father was all for Turing staying in Princeton, you know: "Keep out
of the war; get a prestigious mathematics job". And that was underlined by the fact
that von Neumann offered Turing a job. He basically said: "Turing, would you like to
be my research assistant at the Institute for Advanced Study?" Now
Turing could see, straight away, that would just make you as a mathematician.
You were invited, by the great von Neumann, to be his research assistant, at IAS!
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 that
at that time von Neumann 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 loves. And I don't think Turing 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 thanks, 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 Gottingen to Princeton,
wanted to become the all-American genius. So he was ... on more formal occasions he
was just John von Neumann but to his friends he was "Johnny". You can't
exaggerate 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
shy mathematician. He was all- encompassing and everybody who met him
was just stunned 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 Study, 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 and 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 fact 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 in direct strategic use in gunnery, Actually Johnny,
who by this time *of course* was a consultant to the Moore School, devised a
way, I think, to turn ENIAC into 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 rumours - that
computers are being developed all over the place and you've always got to say:
Are they special-purpose? Are 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 of
computing?", they'll say "Konrad Zuse", He developed electromechanical
machines that were Turing-complete and calculated things. But they never got
beyond electromechanical. You get on to electronic ones - you get Atanasoff
and Berry's electronic, valve driven, thing - special purpose though! Could solve
certain differential equations. And even Tommy Flowers, and Colossus, we know,
special purpose: could decrypt Tunny traffic - Lorenz cipher as 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-based
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, than uncle Johnny of course!
And the Moore School at Pennsylvania, to their great credit, did this. They decided that
the successor to ENIAC would be a thing called EDVAC. They said, yeah, it's
going to 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 ... we'll hold a Summer School in the Moore School of Engineering, 1946,
welcome everybody. Did Turing go to it? He was, I believe, at that time at the
National Physical Laboratory in the UK No he didn't.
Hated conferences did Turing. He wasn't a clubbable character. He couldn't stand
small-talk. Classic shy mathematician not at all like
von Neumann, right? So Turing wasn't, if you like, the UK representative there. And one
wonders whether he would also been held back by Bletchley Park and the Official
Secrets Act because he'd only just left a few years before. The representative from
the UK was somebody who was Turing's exact 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 - Maurice Vincent Wilkes - and by the vagaries of job allocations
around about World War II, he didn't end up at Bletchley Park, did Maurice, he ended
up in radar. But he knew enough about mathematics and electronics to be in a
good position to do, or make, a von Neumann machine in the UK in the period
from about 1946 onwards. But we'd better stop there because Maurice and his EDSAC
is an extra story.