A computer is a device which performs calculations. It comprises of several components, including a processing unit, storage, memory and input/output(I/O) devices.
Storage devices may be magnetic tape, disk units, punched cards, paper tape or CD/DVD.
Input/output devices are printers, screen, keyboard, card or paper tape readers.
A magnetic tape is a storage device , its tape reader/writer is an I/O device.
Computers are controlled by computer programs which can be stored in memory and executed by the processing unit.
The most obvious kind of computer is a desktop personal computer. However, most "computers" that fit the above definition are not desktop or laptop computers. For example, a modern automobile, a cell phone, a digital video recorder, a magnetic resonance imaging scanner, each typically contain more than one "computer" according to the above definition.
The vast majority of computer processors are built from CMOS FET transistors.
Early computer processors were built from relays or vacuum tubes. A few highly experimental computer processors have been built from carbon nanotube FET transistors. In principle, it is possible to build computer processors out of a wide variety of other nonlinear components -- nonlinear optics, fludic gates, spool valves, quantum dots, etc.
- An Illustrated History of Computers, Part 1 or a series, with many images
- Extensive list of sources on the history of computers
- How do computers work? Free Presentations in PowerPoint format
- Computers as a Second Language. Part 1 of series. Explanations of how a computer processes and works
- Roger Young, How Computers Work (book). More extensive technical explanations