Computers

What is a computer? ¯\(°_o)/¯

You might have heard the word "computer" many times, but have you ever wondered what does it mean, what is a computer? The early use of the word computer dates back to 1613 in a book referring a person as a human computer, a person who carried out calculations or computations. Today we refer devices which can be instructed to carry out sequences of arithmetic or logical operations automatically via computer programming as computers. 

History

Devices have been used to aid computation for thousands of years, mostly using one-to-one correspondence with fingers. Then people started using the abacus for computation works. Many mechanical aids to calculation and measurement were constructed for astronomical and navigation use. The first mechanical computers will not be invented until the 19th century. 

The Abacus

Charles Babbage, an English mechanical engineer and polymath, originated the concept of a programmable computer. He is considered as the "father of the computer", he conceptualized and invented the first mechanical computer in the early 19th century. After working on his revolutionary difference engine, designed to aid in navigational calculations, in 1833 he realized that a much more general design, an Analytical Engine, was possible. The input of programs and data was to be provided to the machine via punched cards, a method being used at the time to direct mechanical looms such as the Jacquard loom. For output, the machine would have a printer, a curve plotter and a bell. The machine would also be able to punch numbers onto cards to be read in later. The Engine incorporated an arithmetic logic unit, control flow in the form of conditional branching and loops, and integrated memory, making it the first design for a general-purpose computer that could be described in modern terms as Turing-complete.

The portion of Babbage's Difference Engine.

During the first half of the 20th century, many scientific computing needs were met by increasingly sophisticated analog computers, which used a direct mechanical or electrical model of the problem as a basis for computation. The art of mechanical analog computing reached its zenith with the differential analyzer, built by H. L. Hazen and Vannevar Bush at MIT starting in 1927. This built on the mechanical integrators of James Thomson and the torque amplifiers invented by H. W. Nieman. A dozen of these devices were built before their obsolescence became obvious. By the 1950s, the success of digital electronic computers had spelled the end for most analog computing machines

The ERA of digital computers

Early digital computers were electromechanical; electric switches drove mechanical relays to perform the calculation. These devices were very slow because of their mechanical components. Then after the invention of vacuum tubes it allowed the creation of purely electrical computers to be created which would greatly increase their computing power and speed.

The world war 2 demanded more sophisticated computers to be made to do numerous tasks like calculate ballistic trajectories, break the German encryptions and many more computing heavy tasks. To crack the more sophisticated German Lorenz SZ 40/42 machine, used for high-level Army communications, Max Newman and his colleagues commissioned Flowers to build the Colossus. He spent eleven months from early February 1943 designing and building the first Colossus. After a functional test in December 1943, Colossus was shipped to Bletchley Park, where it was delivered on 18 January 1944 and attacked its first message on 5 February.

Colossus the first electronic digital computer

The ENIAC (Electronic Numerical Integrator and Computer) was the first electronic programmable computer built in the U.S. Although the ENIAC was similar to the Colossus, it was much faster, more flexible, and it was Turing-complete. Like the Colossus, a "program" on the ENIAC was defined by the states of its patch cables and switches, a far cry from the stored program electronic machines that came later. Once a program was written, it had to be mechanically set into the machine with manual resetting of plugs and switches. The programmers of the ENIAC were six women, often known collectively as the "ENIAC girls". The machine was huge, weighing 30 tons, using 200 kilowatts of electric power and contained over 18,000 vacuum tubes, 1,500 relays, and hundreds of thousands of resistors, capacitors, and inductors.

ENIAC

Now we had computers but they were huge and used too much power(Most of them was wasted as heat from the vacuum tubes) and the vacuum tubes were also not reliable, Several tubes burned out almost every day, leaving ENIAC nonfunctional about half the time. Special high-reliability tubes were not available until 1948. Engineers reduced ENIAC's tube failures to the more acceptable rate of one tube every two days. In an interview in 1989 with Eckert one of the inventors of the ENIAC said, "We had a tube fail about every two days and we could locate the problem within 15 minutes."

There was a need to replace the vacuum tubes with something that was reliable small and used less energy to operate. The concept of a field-effect transistor was proposed by Julius Edgar Lilienfeld in 1925. John Bardeen and Walter Brattain, while working under William Shockley at Bell Labs, built the first working transistor, the point-contact transistor, in 1947, which was followed by Shockley's bipolar junction transistor in 1948.From 1955 onwards, transistors replaced vacuum tubes in computer designs, giving rise to the "second generation" of computers. 

A Bipolar Junction Transistor

The next great advance in computing power came with the advent of the integrated circuit (IC). The idea of the integrated circuit was first conceived by a radar scientist working for the Royal Radar Establishment of the Ministry of Defence, Geoffrey W.A. Dummer. Dummer presented the first public description of an integrated circuit at the Symposium on Progress in Quality Electronic Components in Washington, D.C. on 7 May 1952. The development of the MOS integrated circuit led to the invention of the microprocessor, and heralded an explosion in the commercial and personal use of computers. While the subject of exactly which device was the first microprocessor is contentious, partly due to lack of agreement on the exact definition of the term "microprocessor", it is largely undisputed that the first single-chip microprocessor was the Intel 4004, designed and realized by Federico Faggin with his silicon-gate MOS IC technology, along with Ted Hoff, Masatoshi Shima and Stanley Mazor at Intel. In the early 1970s, MOS IC technology enabled the integration of more than 10,000 transistors on a single chip.

Intel 4004 the first Microprocessor

The advent of first microprocessor led to the creation of the first personal computers which made way for the computers, laptops, mobile devices that we use today.