e. Access Time. The time needed to locate and transfer data or instructions
either to or from storage is called access time. The access speed and the amount of
data handled per access have a direct impact on the cost and efficiency of the entire
system. This is true mainly because the central processor is constantly accessing
storage for instructions and data, as well as replacing new data into storage during the
execution of a program. The access time of many computers is so fast that it is
measured in billionths of a second, or nanoseconds.
access time: the time the computer takes to locate and transfer instructions or
data to or from storage.
nanosecond: one billionth of a second (one thousandth of a microsecond).
Section III. COMPUTER SYSTEM LIMITATIONS
2-9.
A COMPUTER CANNOT THINK
A popular misconception is that computers can think. If, for example, a computer
can play a game of chess, how is it that it cannot do the requisite thinking involved in
planning the strategy of the game? The programmers, the people who design the chess
program, provide the strategy in the form of detailed instructions covering every
possible move. The program for a simple game of checkers, for example, requires
hundreds of detailed instructions. Those knowledgeable in the field are quick to remind
us that a computer is not a brain (some would add--at least, not yet). It is simply
another tool, designed to reduce labor and extend our mastery of the world. For all its
apparent brilliance, a modern computer's only capability is to read with lightning speed
coded bursts of voltage. The true brilliance lies with the genius of men and women who
have found ways to translate information from the real world into the Os and the is of
the binary code, the logical and mathematical language of a computer's electronic
2-10. PEOPLE DO SOME JOBS BETTER THAN COMPUTERS
People can perform small complex jobs as well or better than computers. For
example, the time and effort required to program a computer to prepare a complicated
tax report for one-time use is far greater than the effort involved in using pen, pencil,
and paper.
2-11. A COMPUTER CANNOT PROTECT ITSELF
a. Environmental Influences. For all its seeming power and complexity, a
computer can be adversely affected by a number of simple environmental influences.
As seemingly innocent an event as a coffee spill on the keyboard or CPU can harm the
electronic circuitry. A power surge (also known as a "voltage spike," a sudden increase
in power), or an interruption in the supply of electricity, can affect the floppy disk and its
read and write memory. If an operator uses your word processing file disk as a coffee
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