Early computing 3.3

 The first half of the 20th century saw the world's population almost double. But the scale of human systems continued to increase at an unprecedented rate. Global trade and transit networks became interconnected. computing devices, like tabulating machines, were a huge boon to governments and business.

Electro-mechanical computers set the stage for future innovation

  • The Harvard Mark I computer was built by IBM for the Allies during World War II
  • It contained 765,000 components, 3 million connections, and 5 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

The brains of these huge electro-mechanical. beasts were relays:

  • Relays were 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, snapping it shut.

The Harvard Mark I could do 3 additions or subtractions per second

  • Multiplications took 6 seconds, and divisions took 15 seconds. More complex operations, like trigonometric functions, could take over a minute.
  • 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. The probability of a failure increases with the number of relays.

The first vacuum tube

  • 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.
  • 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.

Control electrode

  • Third "control" electrode that sits between the two electrodes in Fleming's design

The History of Vacuum Tubes

  • The first large-scale use of vacuum tubes for computing was the Colossus Mk 1 at Bletchley Park, in the UK, which helped to decrypt Nazi communications
  • It is regarded as the first programmable, electronic computer
  • By the 1950's, even vacuum tube-based computing was reaching its limits, so a radical new electronic switch was needed
  • In 1947, Bell Laboratory scientists John Bardeen, Walter Brattain, and William Shockley invented the transistor
  • 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.

Transistors led to dramatically smaller and cheaper computers, leading to the IBM 608 in 1957

  • It contained 3000 transistors and could perform 4,500 additions, or roughly. 100,000 transistors.
  • Today, computers use transistors that are smaller than 50 nanometers in size, which is incredibly small and fast.

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