AMSTRAD CPC464 User Manual page 196

Q Why, for instance, can' t a computer animate a picture of someone walking across the
screen in a natural fashion - why do all computers represent movement with ' matchstick'
figures?
The answer is simple yet complex. The simple answer is that you must not beguiled into believing
that the screen of your computer has anything of the subtlety of the screen of a TV set. A television
set operates using linear information that can de-scribe a virtually infinite range of resolution
between the extremes of light and dark across all the colours of the spectrum. This process means
that in computer terms, the display ' memory' of a full TV picture is some 20 times more than the
converted equivalent of a home computer video display.
That' s only part of the problem, since to animate this picture requires that this enormous amount of
memory must be processed at high speed (around 50 times each second). It can be done - but only by
machines that cost a few thousand times more than a home computer at least, for the time being!
Until the cost of high speed memory falls dramatically (it will eventually), small computers have to
make do with a relatively small amount of memory available to control the screen display - which
results in lower resolution, and jerkier movements. Thoughtful hardware design and good
programming can go a long way to making the best of this situation, but we are still a way from
cheap computers that can reproduce flowing motion and lifelike pictures in the same way that even a
moderate animated cartoon can produce.
Q Why can' t you simply walk up to the computer and type a page of simple text into the
machine?
Don' t be mislead by the fact that the computer looks like a typewriter with an electronic display. The
screen is not a piece of electronic paper - it' s a command console - jargon which means that it simply
provides you with the means of communicating with the programming language (and the programs)
in the machine memory.