The 20th Century
Global trade and transit networks became more interconnected. Moreover, engineering and scientific endeavours became more sophisticated. The explosion of complexity, bureaucracy, and ultimately data drove an increasing need for automation and computation. The electro-mechanical computers grew into room-sized computers that were prone to errors and expensive to maintain.
Electro-Mechanical
Harvard Mark I and II
One of the largest electro-mechanical computers to be build. Completed in 1944 by IBM for the Allies during World War 2. It’s earliest use was for running simulations for the Manhattan Project. The brains of these huge electro-mechanical machines were relays. Which are electrically-controlled mechanical switches. A control wire in the relay determines whether a cricuit is opened or closed, and it is connected to a coil of wire inside the relay. When current flows through the coil, an electromagnetic field is created, which then attracts a metal arm inside the relay, snapping it shut and completing the circuit. The relay functions like a water faucet. The control wire is like the faucet handle: open the faucet and the water flows through the pipe. Relays do the same thing with electrons instead of water. The controlled circuit can then connect to other circuits or a motor, which might increment a count on a gear. The mechanical arm inside a relay has mass, and can’t move instantly between opened and closed states. It was very slow, and could do 3 additions or subtractions per second. Multiplications took 6 seconds, and divisions took 15. Trigometric functions and other complex operations took over a minute. Wear and tear was another downside. As the number of relays increases, the probability of failure increases too. It had roughly 3500 relays. They also attracted insects, e.g. a bug was discoverd inside the Harvard Mark II in September 1947. Grace Hopper noted, “From then on, when anything went wrong with a computer, we said it had bugs in it.”
Thermionic Valve
The electrical component was developed in 1904 by English physicist John Ambrose Fleming in 1904. It houses 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 through a process called thermionic emission. The other electrode could then attract these electrons to create the flow of the 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. A diode is an electronic component that permits one-way flow of current. A switch is what was needed to help turn this flow on and off.
Triode Vacuum Tube
In 1906, Lee de Forest, an American inventor, added a third control electrode that sits between 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 by manipulating the control wire. The diodes function like relays but without moving parts. Therefore, there was less wear, and they could switch thousands of times per second. The triode vacuum tubes became the basis for radio, long distance telephone, and many other electronic devices. However, they were fragile, and could burn out like light bulbs despite being an improvement to mechanical relays. They were expensive initially, but their cost and reliability had improved by the 1940s.
Electronic Computing
Begun when triode vacuum tubes became cheaper and more feasible for use in computers, which required 1000s of them unlike radios which only required just one. This marked the shift from electro-mechanical to electronic computing.
Colossus MK 1
First large scale use of vacuum tubes for computing designed by Tommy Flowers, and engineer, and completed in December 1943. It was installed at Bletchley Park in the UK, and helped to decrypt Nazi communications. The first version contained 1,600 vacuum tubes, and ten were built for code-breaking. It 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 specific computation.
Electronic Numerical Integrator and Calculator (ENIAC)
Completed in 1947 at the University of Pennsylvania. It was designed by John Mauchly and J. Presper Eckert. It was the world’s trully general purpose, programmable, electronic computer. It could perform 5000, ten-digit additions, subtractions per second many times faster than any machine before it. It was operational for 10 years, and estimated to have done more calculations that the entire human race up to that point. Failures were common because of the numerous vacuum tubes, and was only operational for half a day at a time before breaking down.
Alan Turing
The father of computer science create an electro-mechanical device at Bletchley Park two years before Flowers created the Colossus MK 1. He called it the Bombe.
The Bombe
An electro-mechanical machine designed to break Nazi Enigma codes, but it wasn’t technically a computer.
AN/FSQ-7 Computer
Created by the US Air Force, and was completed in 1955, was part of
Mindmap
Anki Deck
What drove the increasing need for automation and computation in the second half of the 20th century?
Answer
The explosion of complexity, bureaucracy, and ultimately data.
What were the brains of the Harvard Mark I?
Answer
Relays