COMPUTERS. The Machines That Solve Problems.
The first computers were expensive room-sized machines
that only business and government offices could afford. Today most computers
are smaller, and many people have one in their own home or school. These
'personal computers' (PCs) first appeared in the mid-1970s.
Computers can find the answers to many math’s problems
and can simplify work that has many steps and would otherwise take lots of
time. They can do this because they can remember, in order, the individual
steps of even long and complicated instructions.
The sets of instructions for computers are called
'programs' or 'software'. A computer's brain is its microprocessor - a tiny
electronic device that reads and carries out the program's instructions.
Because they are programmed in advance, you can use
computers to solve math’s problems, remember facts, and play games. Computers
can also help you draw, write essays, and make your own greeting cards.
Computers need two kinds of memory. 'Main memory' is
what handles the information that the computer is using as it is doing its
work. Main memory operates amazingly fast and powerfully to speed up a
computer's work. The second kind of computer memory is storage for its programs
and for the results of its operations. The most important storage space is on
the computer's hard drive, or hard disk. CD-ROMs, DVDs, and flash drives are
removable storage devices.
Since 1990 very small computers have been developed.
Today there are laptop or notebook computers, as well as handheld computers.
Handheld computers weigh only a few grams, but they can handle more data more
quickly than most of the first giant computers.
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