Java Reference
In-Depth Information
Programs are sequences of instructions and decisions that the computer carries out to
achieve a task. One program balances checkbooks; a different program, perhaps
designed and constructed by a different company, processes words; and a third
program, probably from yet another company, plays a game.
A computer must be programmed to perform tasks. Different tasks require different
programs.
Today's computer programs are so sophisticated that it is hard to believe that they are
all composed of extremely primitive operations.
A computer program executes a sequence of very basic operations in rapid
succession.
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A typical operation may be one of the following:
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Put a red dot onto this screen position.
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Send the letter
A
to the printer.
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Get a number from this location in memory.
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Add up two numbers.
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If this value is negative, continue the program at that instruction.
A computer program tells a computer, in minute detail, the sequence of steps that are
needed to complete a task. A program contains a huge number of simple operations,
and the computer executes them at great speed. The computer has no intelligenceȌit
simply executes instruction sequences that have been prepared in advance.
A computer program contains the instruction sequences for all tasks that it can
execute.
To use a computer, no knowledge of programming is required. When you write a term
paper with a word processor, that software package has been programmed by the
manufacturer and is ready for you to use. That is only to be expectedȌyou can drive a
car without being a mechanic and toast bread without being an electrician.
