Our last episode brought us to the start of
the 20th century, where early, special purpose computing devices, like tabulating machines,
were a huge boon to governments and business – aiding, and sometimes replacing, rote manual
tasks. But the scale of human systems continued to increase at an unprecedented rate.
The first half of the 20th century saw the world’s population almost double. World
War 1 mobilized 70 million people, and World War 2 involved more than 100 million.
Global trade and transit networks became interconnected like never before, and the sophistication
of our engineering and scientific endeavors reached new heights – we even started to
seriously consider visiting other planets. And it was this explosion of complexity, bureaucracy,
and ultimately data, that drove an increasing need for automation and computation. Soon those cabinet-sized electro-mechanical computers grew into room-sized behemoths that
were expensive to maintain and prone to errors. And it was these machines that would set the
stage for future innovation. INTRO One of the largest electro-mechanical computers built was the Harvard Mark I, completed in
1944 by IBM for the Allies during World War 2. It contained 765,000 components, three
million connections, and five hundred miles of wire. To keep its internal mechanics synchronized, it used a 50-foot shaft running right through
the machine driven by a five horsepower motor. One of the earliest uses for this technology
was running simulations for the Manhattan Project. The brains of these huge electro-mechanical beasts were relays: electrically-controlled
mechanical switches. In a relay, there is a control wire that determines whether a circuit
is opened or closed. The control wire connects to a coil of wire inside the relay. When current
flows through the coil, an electromagnetic field is created, which in turn, attracts
a metal arm inside the relay, snapping it shut and completing the circuit. You can think
of a relay like a water faucet. The control wire is like the faucet handle. Open the faucet,
and water flows through the pipe. Close the faucet, and the flow of water stops. Relays are doing the same thing, just with electrons instead of water. The controlled
circuit can then connect to other circuits, or to something like a motor, which might
increment a count on a gear, like in Hollerith’s tabulating machine we talked about last episode.
Unfortunately, the mechanical arm inside of a relay *has mass*, and therefore can’t
move instantly between opened and closed states. A good relay in the 1940’s might be able
to flick back and forth fifty times in a second. That might seem pretty fast, but it’s not
fast enough to be useful at solving large, complex problems.
The Harvard Mark I could do 3 additions or subtractions per second; multiplications took
6 seconds, and divisions took 15. And more complex operations, like a trigonometric function, could take over a minute. In addition to slow switching speed, another
limitation was wear and tear. Anything mechanical that moves will wear over time. Some things
break entirely, and other things start getting sticky, slow, and just plain unreliable. And as the number of relays increases, the probability of a failure increases too. The
Harvard Mark I had roughly 3500 relays. Even if you assume a relay has an operational life
of 10 years, this would mean you’d have to replace, on average, one faulty relay every
day! That’s a big problem when you are in the middle of running some important, multi-day
calculation. And that’s not all engineers had to contend
with. These huge, dark, and warm machines also attracted insects. In September 1947,
operators on the Harvard Mark II pulled a dead moth from a malfunctioning relay. Grace Hopper who we’ll talk more about in a later episode noted, “From then on, when anything went wrong with a computer, we said it had bugs in it.” And that’s where
we get the term computer bug. It was clear that a faster, more reliable
alternative to electro-mechanical relays was needed if computing was going to advance further,
and fortunately that alternative already existed! In 1904, English physicist John Ambrose Fleming
developed a new electrical component called a thermionic valve, which housed two electrodes
inside an airtight glass bulb – this was the first vacuum tube. One of the electrodes could
be heated, which would cause it to emit electrons – a process called thermionic emission.
The other electrode could then attract these electrons to create the flow of our electric
faucet, but only if it was positively charged – if it had a negative or neutral charge,
the electrons would no longer be attracted across the vacuum so no current would flow. An electronic component that permits the one-way flow of current is called a diode, but what
was really needed was a switch to help turn this flow on and off. Luckily, shortly after,
in 1906, American inventor Lee de Forest added a third “control” electrode that sits
between the two electrodes in Fleming’s design. By applying a positive charge to the
control electrode, it would permit the flow of electrons as before. But if the control
electrode was given a negative charge, it would prevent the flow of electrons.
So by manipulating the control wire, one could open or close the circuit. It’s pretty much
the same thing as a relay – but importantly, vacuum tubes have no moving parts. This meant
there was less wear, and more importantly, they could switch thousands of times per second.
These triode vacuum tubes would become the basis of radio, long distance telephone, and
many other electronic devices for nearly a half century. I should note here that vacuum
tubes weren’t perfect – they’re kind of fragile, and can burn out like light bulbs,
they were a big improvement over mechanical relays. Also, initially vacuum tubes were expensive – a radio set often used just one, but a
computer might require hundreds or thousands of electrical switches. But by the 1940s,
their cost and reliability had improved to the point where they became feasible for use
in computers…. at least by people with deep pockets, like governments.
This marked the shift from electro-mechanical computing to electronic computing. Let’s
go to the Thought Bubble. The first large-scale use of vacuum tubes
for computing was the Colossus Mk 1 designed by engineer Tommy Flowers and completed in
December of 1943. The Colossus was installed at Bletchley Park, in the UK, and helped to
decrypt Nazi communications. This may sound familiar because two years
prior Alan Turing, often called the father of computer science, had created an electromechanical
device, also at Bletchley Park, called the Bombe. It was an electromechanical machine
designed to break Nazi Enigma codes, but the Bombe wasn’t technically a computer, and
we’ll get to Alan Turing’s contributions later.
Anyway, the first version of Colossus contained 1,600 vacuum tubes, and in total, ten Colossi
were built to help with code-breaking. Colossus is regarded as the first programmable, electronic computer. Programming was done by plugging hundreds
of wires into plugboards, sort of like old school telephone switchboards, in order to
set up the computer to perform the right operations. So while “programmable”, it still had
to be configured to perform a specific computation. Enter the The Electronic Numerical Integrator
and Calculator – or ENIAC – completed a few years later in 1946 at the University
of Pennsylvania. Designed by John Mauchly and J. Presper Eckert, this was the world’s first truly general purpose, programmable, electronic computer. ENIAC could perform 5000 ten-digit additions
or subtractions per second, many, many times faster than any machine that came before it.
It was operational for ten years, and is estimated to have done more arithmetic than the entire
human race up to that point. But with that many vacuum tubes failures were
common, and ENIAC was generally only operational for about half a day at a time before breaking
down. Thanks Thought Bubble. By the 1950’s, even
vacuum-tube-based computing was reaching its limits. The US Air Force’s AN/FSQ-7 computer,
which was completed in 1955, was part of the “SAGE” air defense computer system we’ll
talk more about in a later episode. To reduce cost and size, as well as improve
reliability and speed, a radical new electronic switch would be needed. In 1947, Bell Laboratory
scientists John Bardeen, Walter Brattain, and William Shockley invented the transistor,
and with it, a whole new era of computing was born! The physics behind transistors is
pretty complex, relying on quantum mechanics, so we’re going to stick to the basics. A transistor is just like a relay or vacuum
tube – it’s a switch that can be opened or closed by applying electrical power via
a control wire. Typically, transistors have two electrodes separated by a material that
sometimes can conduct electricity, and other times resist it – a semiconductor.
In this case, the control wire attaches to a “gate” electrode. By changing the electrical
charge of the gate, the conductivity of the semiconducting material can be manipulated,
allowing current to flow or be stopped – like the water faucet analogy we discussed earlier.
Even the very first transistor at Bell Labs showed tremendous promise – it could switch
between on and off states 10,000 times per second. Further, unlike vacuum tubes made
of glass and with carefully suspended, fragile components, transistors were solid material known as a solid state component. Almost immediately, transistors could be made smaller than the smallest possible relays or vacuum tubes. This led to dramatically smaller and cheaper computers, like the IBM 608, released in 1957 – the first fully transistor-powered, commercially-available computer. It contained 3000 transistors and
could perform 4,500 additions, or roughly 80 multiplications or divisions, every second.
IBM soon transitioned all of its computing products to transistors, bringing transistor-based
computers into offices, and eventually, homes. Today, computers use transistors that are
smaller than 50 nanometers in size – for reference, a sheet of paper is roughly 100,000
nanometers thick. And they’re not only incredibly small, they’re super fast – they can switch
states millions of times per second, and can run for decades. A lot of this transistor and semiconductor development happened in the Santa Clara Valley, between San Francisco and San Jose, California. As the most common material used
to create semiconductors is silicon, this region soon became known as Silicon Valley.
Even William Shockley moved there, founding Shockley Semiconductor, whose employees later
founded Fairchild Semiconductors, whose employees
later founded Intel – the world’s largest computer chip
maker today. Ok, so we’ve gone from relays to vacuum
tubes to transistors. We can turn electricity on and off really, really, really fast. But
how do we get from transistors to actually computing something, especially if we don’t
have motors and gears? That’s what we’re going to cover over
the next few episodes. Thanks for watching. See you next week.

Electronic Computing: Crash Course Computer Science #2
Tagged on:                                                                                                                                     

100 thoughts on “Electronic Computing: Crash Course Computer Science #2

  • May 4, 2018 at 6:18 pm
    Permalink

    forgot to mention voltage/current levels in Direct Current (DC) its not as simple as 1 and 0 at this level so, IIRC, we have different voltage output wires which come from the transformer and a high current typically is represented as 1 and a base current is considered 0. the base current is pulled hi to a high current. there are PNP and NPN transistors as well as mosfets.

    Reply
  • May 8, 2018 at 9:38 am
    Permalink

    50 nanometres?! What the actual f#@k?!

    Reply
  • May 13, 2018 at 8:47 pm
    Permalink

    I live in San Jose… I'm so proud…. sheds a tear

    Reply
  • May 23, 2018 at 2:24 am
    Permalink

    Those are some huge computers.

    Reply
  • May 25, 2018 at 5:30 am
    Permalink

    DEEP POCKETS

    Reply
  • May 27, 2018 at 10:10 pm
    Permalink

    The math doesn't work for the Harvard Mach 1 relays example. If an Average relay has an operational life of 10 years with 3500 relays, on average rate of replacement of relays is 140/day???? I did the math and comes out as 0.958 relay/day ≈ 1/day.

    Reply
  • June 1, 2018 at 7:08 pm
    Permalink

    If they hadn't invented the transistors, we could have been in the Fallout universe by now.

    Reply
  • June 22, 2018 at 7:34 pm
    Permalink

    I think I was not looking for this!

    Reply
  • June 22, 2018 at 7:36 pm
    Permalink

    Where is Zuckerberg ranked in this history??

    Reply
  • June 22, 2018 at 8:22 pm
    Permalink

    Fawcett?

    Reply
  • June 22, 2018 at 8:24 pm
    Permalink

    No, Fleming invented the diode and the triode. Lee Forrest was a charlatan as was proved later.

    Reply
  • June 30, 2018 at 4:52 pm
    Permalink

    Thank you so much for putting money where it matters!!

    Reply
  • July 2, 2018 at 9:12 pm
    Permalink

    I expected to learn more than just some names

    Reply
  • July 15, 2018 at 12:10 am
    Permalink

    187 manual extinct calculator professionals dislike this video

    Reply
  • July 24, 2018 at 9:00 am
    Permalink

    Charles Cabbage <3

    Reply
  • August 10, 2018 at 4:50 pm
    Permalink

    so computers are basically just machines that control the flow of electricity/electrons from On and Off? Is this where binary comes in? 0 and 1.

    Reply
  • August 11, 2018 at 5:09 am
    Permalink

    It sounds like if you have already had an electronics course, then this course is a waste of time.

    Reply
  • August 16, 2018 at 3:50 pm
    Permalink

    Who else is procrastinating?

    Reply
  • August 22, 2018 at 5:45 am
    Permalink

    damnit this is so well presented my 2 year old son could understand it.

    Reply
  • August 24, 2018 at 1:05 am
    Permalink

    AMD

    Reply
  • August 30, 2018 at 3:28 am
    Permalink

    Typo in description: But is was these computers that would help usher in a new era of computation – electronic computing.

    Reply
  • September 7, 2018 at 1:04 am
    Permalink

    I think sand was being mined from Scotts Valley or somewhere in Santa Cruz County to make the silicon for the computers and many companies came to Santa Clara creating the Silicon Valley. Yup! We're not just a surfer hippie town. 🙂

    Reply
  • September 9, 2018 at 12:20 pm
    Permalink

    Is this crash course for ocr or aqa? I'm trying to teach myself computer science at home but I'm not sure what exam board this covers.

    Reply
  • September 19, 2018 at 11:05 am
    Permalink

    Such a Bad Video

    Reply
  • September 25, 2018 at 9:56 am
    Permalink

    anyone in class i am lol so boring

    Reply
  • October 10, 2018 at 5:49 pm
    Permalink

    why is the puny title on spanish

    Reply
  • October 13, 2018 at 7:03 am
    Permalink

    Great video, but it was John Bardeen (long "e") not Barden. John Bardeen is one of my friend's great uncle so I have heard his name pronounced by a blood relative.

    Reply
  • October 17, 2018 at 2:59 pm
    Permalink

    Love this very much thank you very much

    Reply
  • October 18, 2018 at 11:47 pm
    Permalink

    insert moth meme here

    Reply
  • October 21, 2018 at 9:24 am
    Permalink

    That is absolutely NOT where we get the term computer bug from. Very poor researching indeed.

    Reply
  • October 23, 2018 at 3:53 am
    Permalink

    This series is amazing!!

    Reply
  • October 31, 2018 at 1:19 pm
    Permalink

    I never knew where "bugs" came from. That's so cool!

    Reply
  • November 4, 2018 at 3:09 pm
    Permalink

    This is an interesting crash course in computer technology, but has very little to do with computer science. The analogy would be to focus on the history of calculators when talking about the field of mathematics. Computer science is all about the science of computation. The field of computer science predates mechanical and electronic computers because people needed algorithms for computing data quickly. A computer scientist rarely needs a computer to do their R&D. BTW the term "bug" pre-dates the famous case of the Mark II moth. The term was frequently used by engineers and scientists before the 20th century and you can tell by the notes on the Mark II log "First actual case of bug being found.", which wouldn't make sense unless the term bug was previously used to describe a problem.

    Reply
  • November 11, 2018 at 10:17 am
    Permalink

    What about Konrad Zuse????…

    Reply
  • November 11, 2018 at 10:19 am
    Permalink

    Z1 is faster than its contemporaries!!! And Jackard?

    Reply
  • November 29, 2018 at 8:32 pm
    Permalink

    I JUST WATCHED THIS AND OH MY GOD!! … I still don't get it

    Reply
  • December 2, 2018 at 5:48 am
    Permalink

    So making a computer has a lot to do with making smaller, more durable, and faster switches… Very fascinating.

    Reply
  • December 3, 2018 at 10:02 am
    Permalink

    who that guy with the cig in his hand at 0:53 ??

    Reply
  • December 4, 2018 at 9:17 pm
    Permalink

    Thanks Austin Powers' sister.

    Reply
  • December 13, 2018 at 1:59 am
    Permalink

    BUT HOW DO IT KNOW?

    Reply
  • December 13, 2018 at 2:20 pm
    Permalink

    Now where do I find out how transistors work?

    Reply
  • December 16, 2018 at 5:05 pm
    Permalink

    What about the Zuse Z1 and Z3??? The Z1 was a mechanical 24 bit FPU CPU made in 1936. The Z3 was like the Z1 but this one used relays entirely and could extract square roots too. The Z3 was completed in 1941.

    Reply
  • December 19, 2018 at 4:54 pm
    Permalink

    When was exactly the binary arithmatic started to be used in computers

    Reply
  • December 23, 2018 at 10:51 pm
    Permalink

    The Colossus had to be programmed by moving wires but not the ENIAC. Does this mean that ENIAC supported a programming language like for example Python, C or Java?

    Reply
  • December 25, 2018 at 5:36 pm
    Permalink

    Expected some more details on Turning's contribution. But anyway, superb video

    Reply
  • December 25, 2018 at 5:38 pm
    Permalink

    Indianapolis? Is Carrie Anne American or British ?

    Reply
  • December 29, 2018 at 6:19 pm
    Permalink

    2:54 . – .- – .- – .- – .- . ..- ?

    Reply
  • December 31, 2018 at 2:40 am
    Permalink

    "sticky, slow, and just plain unreliable" – sounds like me Lol

    Reply
  • January 4, 2019 at 12:44 am
    Permalink

    I'm pretty late to seeing this series, and a new watcher of Crash Course, but I'm hoping to eventually get a degree in computer engineering and this is some of the most fascinating material I've ever watched, presented in a manner that my dumb brain can understand it. Thank you very much!

    Reply
  • January 4, 2019 at 8:53 pm
    Permalink

    Konrad Zuse

    Reply
  • January 6, 2019 at 1:54 am
    Permalink

    Bloody brilliant videos

    Reply
  • January 14, 2019 at 4:09 am
    Permalink

    6:22 …so I pressed F10 to "Save", but it just muted the audio.

    Reply
  • January 22, 2019 at 2:30 pm
    Permalink

    this is trash

    Reply
  • January 22, 2019 at 2:35 pm
    Permalink

    this is trash too

    Reply
  • January 22, 2019 at 2:35 pm
    Permalink

    she is an oger

    Reply
  • January 22, 2019 at 2:37 pm
    Permalink

    shes shrek

    Reply
  • January 22, 2019 at 2:37 pm
    Permalink

    i smell penies

    Reply
  • January 22, 2019 at 2:39 pm
    Permalink

    i smell pennies

    Reply
  • January 22, 2019 at 2:41 pm
    Permalink

    why you so mean to me

    Reply
  • January 25, 2019 at 9:20 pm
    Permalink

    Great channel

    Reply
  • January 29, 2019 at 11:29 am
    Permalink

    أين نجدها مترجمة أو مدبلجة للعربية .

    Reply
  • February 3, 2019 at 3:27 am
    Permalink

    From a guitar guy's view
    Very appreciate that you have a valve in your hand.
    I can't get focused on anything with these fantastic looking bulbs!

    Reply
  • February 10, 2019 at 6:42 am
    Permalink

    Question: You said Harvard Mark 1 had 3500 relays and if each relay has 10 years of life. Then how you came up on the conclusion that you have to replace 140 relays every day. I didn't understand math behind this. Could you/anyone help me?

    Reply
  • February 10, 2019 at 7:32 am
    Permalink

    Omg this chick so ugly I can't even use this 😒. The guys at least wear decent clothes and try to be funny. She in a ratty t and not funny at all

    Reply
  • February 18, 2019 at 10:18 am
    Permalink

    7:07 it sounds like she's blaming thought bubble

    Reply
  • February 26, 2019 at 5:56 am
    Permalink

    please subtitle indonesia bro

    Reply
  • March 18, 2019 at 6:25 pm
    Permalink

    good

    Reply
  • March 18, 2019 at 10:12 pm
    Permalink

    8:42 that's showing a vacuum tube and a film capacitor side by side as they're talking about the size of a transistor to a vacuum tube am I wrong? Maybe I just don't know what early transistors looked like

    Reply
  • March 31, 2019 at 4:39 am
    Permalink

    literally computer bug! 😁 awesome

    Reply
  • April 3, 2019 at 2:50 pm
    Permalink

    These videos are immensely informative thanks so much

    Reply
  • April 14, 2019 at 9:37 pm
    Permalink

    If it wasn’t for quantum mechanics

    Reply
  • April 16, 2019 at 9:52 pm
    Permalink

    Wow this course is GOD DAMN HELPFUL and REALLY AMAZING 😍😍😍😍 Thank you so much 🤗

    Reply
  • April 20, 2019 at 8:08 am
    Permalink

    no offense to the lady doing the talking on the video,but Im gonna suggest that your should speak a bit slower for the sake of learning,again no offense,just an observation,you talk way to fast for a video that is meant to teach people,content is awesome but way to fast paced. we know it will drive the video to get heavier and longer but it will be nice to learn on a slower rithm

    Reply
  • April 23, 2019 at 4:16 pm
    Permalink

    My teacher is making me watch this it’s pretty stupid if you ask me lol Dislike this video

    Reply
  • April 23, 2019 at 10:41 pm
    Permalink

    1:04 Harvard Mark I
    2:33 Additions, Subtractions, Multiplications, Divisions. Computer Bugs
    3:34 John Ambrose Fleming, Thermionic Valve.
    Lee de Forest
    4:55 Triode Vacuum Tubes
    5:31 Electronic Computing. Colossus MK1. Alan Turing
    6:35 ENIAC
    7:40 A Transistor. Computers get smaller, Computers get cheaper
    9:35 Silicon Valley

    Reply
  • April 28, 2019 at 8:47 am
    Permalink

    In the future I will share these presentations with my kids, not school.

    Reply
  • May 9, 2019 at 10:20 am
    Permalink

    grace hopper said there was a bug in it?
    thats where you got the term computer bugs?
    when you say grace hopper, i say grass hopper!!!

    Reply
  • May 12, 2019 at 9:21 pm
    Permalink

    Watching day before computer science exam 😢😢😢

    Reply
  • May 13, 2019 at 10:45 pm
    Permalink

    Who else is watching this on their tabulating device

    Reply
  • May 25, 2019 at 8:19 pm
    Permalink

    You forgot Konrad Zuse…

    Reply
  • May 31, 2019 at 10:03 am
    Permalink

    I used this for my homework, and it’s a very good source👌

    Reply
  • June 2, 2019 at 10:16 pm
    Permalink

    Why cant i find girl friends like this one?

    Reply
  • June 4, 2019 at 2:47 pm
    Permalink

    Увольняйте того, кто писал субтитры на русском

    Reply
  • June 17, 2019 at 12:53 pm
    Permalink

    mam, u told that 140 relays need to be changed every day… please tell me how u, calculated the no of relay

    Reply
  • June 17, 2019 at 6:30 pm
    Permalink

    When you realise that for the first time, most people here are actually professionals and not desperate kids grabbing at a last minute oppurtunity to cram stuff

    Unlike me. Sigh.

    Reply
  • June 19, 2019 at 8:20 am
    Permalink

    Solid-State Drives and both types of Random Access Memory use transistors.

    Reply
  • June 22, 2019 at 4:56 pm
    Permalink

    My goal is to spend the most time on the computer than anyone in history.

    Reply
  • June 26, 2019 at 8:39 pm
    Permalink

    6:35 The C in ENIAC stands for “computer” and not “calculator”.

    Reply
  • June 27, 2019 at 12:18 pm
    Permalink

    Why is she speaking so quickly? Love it tho

    Reply
  • July 3, 2019 at 8:59 am
    Permalink

    3:29 "grace hopper" HAHAHAHAHAHAHAHA

    Reply
  • July 16, 2019 at 7:40 am
    Permalink

    영상만들어주신분과 자막만들어 주신분께 감사합니다.

    Reply
  • July 25, 2019 at 4:16 am
    Permalink

    Thank you mam

    Reply
  • July 28, 2019 at 5:49 am
    Permalink

    What is a thought bubble?

    Reply
  • August 6, 2019 at 9:01 pm
    Permalink

    3:18 Did anyone else think of the smashed bug in the printer which sets events in motion in the movie "Brazil?"

    Reply
  • August 31, 2019 at 6:52 pm
    Permalink

    Next video: “How to overclock a vacuum tube”

    Reply
  • September 13, 2019 at 12:41 pm
    Permalink

    Fascinating that "bugs" comes from this, had no idea and never thought about looking it up for some reason.

    Reply
  • September 19, 2019 at 1:49 am
    Permalink

    9/10
    Too much computer.
    – ign

    Reply
  • September 21, 2019 at 6:04 pm
    Permalink

    nice vid

    Reply
  • October 3, 2019 at 12:10 am
    Permalink

    did some one get the nerd joke? (the glasses) it's a reference to Grace Hopper 😉

    Reply

Leave a Reply

Your email address will not be published. Required fields are marked *