A Brief* History of Computers. *I\'m leaving out a lot , believe me. First, what is a computer?. During WWII, people who performed calculations (sometimes with adding machines or slide rules) were known as computers.
*I\'m leaving out a lot, believe me. . .
A loom controlled by punched cards, rather than by a master weaver
Led to the Luddite rebellion in England (1811-1816 )
Even now, people who are hostile to technology are sometimes called Luddites
Charles Babbage (1792-1871) is known as the father of the computer. The analytical engine (a part of which is shown above) anticipated many of the features of a modern computer. He worked on it from 1837 to 1871, but it was never completed. Nothing equivalent came along again until the 1940s.
(information on the Analytical Engine is mostly from "The Cartoon Guide to the Computer" by Larry Gonick.)
The Analytical Engine had 4 major components:
The Mill was basically an adding machine. It could add, subtract, multiply and divide, accurate to 50 decimal places.
Input was via punch cards, like Jacquard\'s loom. The cards specified not only the numbers to be used, but also the instructions – what the mill should to with the numbers.
The Store: a set of 1000 "registers", each able to hold a single 50 digit number. The registers could be loaded from punch cards, or from results produced by the mill.
Output: the results of computations would be printed through an automated typesetter
She wrote out sequences of instructions for the analytical engine – the first computer programs. She developed some fundamental concepts which are the basis for computer programs to this day:
Subroutines: sequences of instructions that can be reused in different contexts.
Looping: an instruction should exist to back up the card reader to a specific card, so that the sequence of instructions can be executed over and over
Conditional jump: the card reader should be able to skip forward or backward to another card IF some condition is satisfied – say, if two numbers in the store are equal.
If Charles Babbage is the father of the computer, it\'s fair to say that Ada Lovelace is the mother.
These were created for the 1890 census. They led to the first commercial data processing machines. . . And this was the beginning of IBM.
Relays are mechanical switches controlled by electromagnets. They are very reliable, cheap, and use little power, but are slow compared to electronic devices. Invented in 1835.
Vacuum tubes are electronic devices that can also be used to to switch electrical currents on and off. They are about 1000 times faster than relays, but use lots of energy, generate lots of heat, and can burn out. Originated in early 1900s.
A SAGE building
Part of one of the computers
Magnetic core memory
Transistors can serve as switches in digital circuits, much like vaccuum tubes. But they are smaller, cheaper, require less power, and are more reliable. The transistor was invented in 1947, at Bell Labs. The first transistorized computer was TRADIC, in 1954.
The integrated circuit (IC) was invented by Jack Kilby of Texas Instruments in 1958. Using photographic methods, many transistors and other components can be built up on a chip, layer by layer. The components on the chip are connected to one another by conductors within the chip itself, rather than external wires. Current state-of-the-art chips have transistors so tiny that 2000 of them fit in the width of a human hair, and 30 million on the head of a pin. IBM’s new Power6 chip has 700 million transistors.
Doug Engelbart was one of the first people to realize that computers could augment people – help them do their work – rather than replace people by automating tasks. He gave a live demo of his online system, NLS, at the Joint Computer Conference in 1968 in San Francisco. That day he demonstrated:
Xerox Alto, 1973 – an early minicomputer, the first to use a GUI and desktop metaphor
The Altair 8800 is commonly regarded as the beginning of the personal computer era, in 1975. It was sold as a kit for $595, with an 8080 processor running at 2 Mhz, and 256 bytes of memory. As sold, It had no keyboard – programs and data were input through switches on the front, and output was via blinking lights. Additional memory and devices could be added.
Bill Gates and Paul Allen started Microsoft to write software for the Altair.
IBM Personal Computer, 1981
$3000 with 16K memory, 4.77 Mhz 8088 processor,
No hard drive
Apple II – 1977
$1298 with 4K RAM, $2638 with 48K RAM. 1 Mhz 6502 processor.
Compaq Portable, 1983 $3500. 4.77 Mhz 8088 processor, 128K of RAM. Weighed 28 pounds – no battery, you had to plug it in.
Apple Macintosh, 1984
$2495 with 128K RAM, 7.83 Mhz 68000 processor
Apple Macintosh Portable: 1989 $7300 w/ hard drive. 16 Mhz 68000 processor, 1 Meg memory. Weighed 16 pounds, including battery
IBM Personal Computer, 1981
$3000 with 4.77 Mhz Intel 8088 processor, 16K memory,
monochrome monitor (no graphics), no hard drive
Dell XPS 720 Red Computer, 2007
$2949 with 3 Ghz Intel Core Duo processor, 2 GB memory, 160 GB hard drive