What A Computer Is (And Isn't) For

  There seems to be a fundamental misunderstanding among many computers users
about just what a computer is meant to be used for. This list shall set the
record straight.
  Note that it may be more useful for most to start with what computers are
NOT for, and therefore, we'll begin with...

Things A Computer Isn't For

  A computer is not for creating documents. This can be done with a
hard-coded word processor.
  A computer is not for viewing digital photographs. This can be done with a
hard-coded viewing device.
  A computer is not for browsing the Web, or sending and receiving e-mail.
This can be done with hard-coded Internet terminals, and now also with many
cell phones.
  A computer is not for making mathematical calculations. This can be done
with a calculator.
  A computer is not for playing games. This can be done with a video game
console (although not as well).
  A computer is not for storing data. This can be done with paper or
microfilm.
  A computer is not for complementing the decor of a location. This can be
done with flowers, paintings, tablecloths, and the like.
  A computer can do all of the above things. However, these things are all
possible without a computer; these applications are not the purpose for a
computer.

Things A Computer Is For

  A computer is a microprocessor interfaced to some memory and I/O circuits.
A computer with a person using it directly often also has a monitor and
keyboard.
  A computer is for allowing you to change any value in any memory cell at
any point in time, because the user or programmer wants to, regardless of
what might currently be in that memory cell or what it's being used for. The
exception, of course, is ROM, but a computer is also for allowing you to
reprogram the computer's ROM chip(s), because the user or programmer wants
to, regardless of what might currently be in that ROM chip.
  A computer is for allowing you to change the value in any microprocessor
register at any time, because the user or programmer wants to, regardless of
what might currently be in that register or what it's being used for.
  A computer is for sending any data value to any output port at any time,
and reading any data value from any input port at any time, because the user
or programmer wants to.
  A computer is for soldering a wire to any point in the circuit, because the
user or programmer wants to tap into that circuit net.
  If the computer has semi-permenent storage, then the computer is also for
setting any piece of magnetic material on a disk, or any region of an optical
disc, to a 0 or a 1 at any time, because the user or programmer wants to,
regardless of what that piece of media might currently be set to.
  If the computer has a monitor, then the monitor is for allowing you to
change the color and brightness of any pixel on the screen at any time,
because the user or programmer wants to, regardless of what else is currently
on the screen.
  If the computer has a keyboard, then the keyboard is for entering any
numerical digit, letter in the alphabet, or punctuation mark by pressing a
single button, because the user or programmer wants to, without having to
fiddle with piggybacked keys or metakeys.
  If the computer has speakers and a sound controller, then the computer is
also for playing any sound or musical note--digitized, synthesized, or
otherwise--through those speakers at any time, because the user or programmer
wants to.
  A computer is for creating sequences of bits in memory and having the
microprocessor execute those bits as instructions in sequential order.
  A computer must be able to do all these things. If a device is not capable
of all of these, it is not actually a computer.
  The other thing that a computer is for is to be understood. Even if the
computer fulfills no other practical purpose, it has achieved some end by
being a functional, understandable device. In order for a device to be a
computer, it must have all of its memory addresses, all of its interrupt
routines, all of its hardware connections, and all of its I/O addresses made
clear, open, visible, accessible, and understandable to anyone and everyone.
If a device lacks this level of understandability, it does not perform the
basic functions that a computer serves. After all, a computer is by nature an
information device; the purpose of a computer is to receive, store, process,
and present information. If information about the computer itself is
concealed, then the so-called "computer" is not actually a computer,
regardless of what happens when you turn it on.