History of Computers



History of Computers

Computers as we know them are relatively new devices. The first electronic computers date back only to the 1940s.

Generation 0: Mechanical Computers (1642-1945)

The earliest prototype of a calculator that has survived is that of Blaise Pascal who built a mechanical calculator in 1642 (he was 19). A person could enter numbers up to eight digits long and add or subtract.

(reading about him in lab)

Programmable Devices: Mechanical calculators were popular in 1800s, but the first programmable machine was not a calculator, but a loom. 1801, Joseph-Marie Jacquard invented a programmable loom in which removable punch cards were used to represent patterns. Before this invention producing tapestries and patterned fabric was complex and tedious work done by people and now was replaced by machine.

Jacquard’s idea of storing information as holes punched into cards resurfaced in the work of Charles Babbage (mathematician). He incorporated punch cards in the 1821 design of his Difference Engine, a steam-powered mechanical calculator for solving mathematical equations (not fully functional). In 1833 Babbage expanded on his plans for the Difference Engine to design a more powerful machine – Analytical Engine – general purpose programmable computer that accepted input via punched cards and printed output on paper. A working model was never completed, but its design was popularized by the writings of Augusta Ada Byron, Countess of Lovelace. Therefore, she is known as the world’s first programmer.

Late 19th Century – Hollerith – used punch cards for a tabulating machine to sort and tabulate data for the 1890 US Census.

1930s - Electromagnetic Relays – mechanical switch used to control the flow of electricity through a wire

Generation 1: Vacuum Tubes (1945 – 1954)

Electromagnetic relays are faster than wheels, still limited by moving parts. Example: (1945 - Grace Murray Hopper, working on the Mark II computer, a computer failure was traced to a moth that had become wedged between relay contacts. She taped the moth into the logbook – that was the first case of a bug being found.) (trick – grasshopper)

Replaced electromagnetic relays with vacuum tubes - small glass tubes from which all or most of the gas has been removed, permitting electrons to move with minimal interference from gas molecules.

Vacuum tubes – capable of controlling the flow of electricity.

Nothing could get stuck – better way to manage electricity.

World War 2 hasted the development of electronic (vacuum tube) computer. Colossus (pronounced culahssus)(first electronic computer) British decrypted Nazi communications

1944- picture of Colossus Mark I

Same time in US – ENIAC –

1946-

Huge – faster and more complex calculator.

The ENIAC represented still a stepping stone towards the true computer – included parallel computation.

Von Neumann – involved with eniac. – von Neumann adopted “stored-program” architecture. A program could be read in and stored in the computer’s memory. At first programs were written in machine language, then assembly language.

1948 - Manchester Mark I - one of first "real" computers with stored programs

Generation 2: transistors (1954 – 1963)

Vacuum tubes – large and needed lots of space for cooling. Vacuum tubes were replaced with transistors. Transistors – smaller, cheaper, more reliable, etc. this produced smaller and faster machines.

Transistor – piece of silicon – conduct electricity faster and smaller and cheaper. Helped with televisions, radios, etc – better electricity.

At the same time, high-level programming languages are being developed. The first language = FORTRAN (1957)

Generation 3: Integrated Circuits: (1963-1973)

Transistors improved over vacuum tubes, but complex with thousands of transistors. Therefore transistors were layered together onto the same disc and connected to form simple circuits. This was known as an integrated circuit or IC chip. This made it possible to build computers that were smaller, faster, and cheaper. Instead of starting with transistors, and engineer could build computers out of prepackaged IC chips, which simplified design and construction tasks.

(In 1971, Intel combined all the control circuitry for a calculator into a single chip called a microprocessor. )

Generation 4: VLSI (1973 – 1985)

Very large scale integration – hundreds of thousands and eventually millions of transistors on an IC chip.

Cost of computers dropped where individuals could afford them. MITS Altair 8800 was the first pc.

1975 - MITS ALTAIR 8800 - first personal computer - cost $375 had only 265 bytes of memory!

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