What is a
Computer ?
A
computer is a electronic machine capable of solving problems by processing
or manipulating information according to instructions that have been given
to it.
When we say processing or
manipulating, we mean that information is changed in some way. If we have
typed in a list of employees into the computer, and we want to alphabetize
the list, the act of placing the names in alphabetical sequence is
considered as processing.
Electronically all computers
work pretty much the same way. Even though there are several
categories of computers, we will concentrate only on the Microcomputers in
this tutorial (commonly known as " Personal
Computers").
There are four basic categories of
computers:
Microcomputer (PC) A small desktop or laptop. Common
desktop PCs are Gateway 2000, IBM Dell, Micronics, etc. Common LAPTOPs are
Toshiba, IBM ThinkPad, etc. Their cost as new devices may range from
$600.00 to around $5000.00.
 Minicomputers. Mid-size computers,
non-portable types. Common minicomputers are DEC Vax/750 models. They
often appear as mainframes. They are gradually disappearing from the
marketplace.
Mainframe Computers. These are
large computers, often occupying a large room. They are generally used by
banks, universities, and some government functions such as IRS, etc. They
lost sales during the 1980-1991 era, but were predicted to regain some
leverage in 1993 and 1994. They may continue to lose ground with the
advent of some smaller computers such as the Zenith Z-Server, DEC
AlphaServer, and other multi-CPU products housed in small cabinets.
 Supercomputers. The most powerful
computers. They are very fast, and have extremely high storage capacity,
probably in the terra byte range. Used in research, weather forecasting,
modeling or simulations, etc.
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