SOUNDMACHINE ST by Richard Karsmakers
Introduction; the principles of digitized music
Back in 1987, right in the beginning of the ST's era, a hackin'
group called 'The Desaster Area' made a couple of sound demos
("Oxygene", "Matt's Mood" and another one of which the title
slipped my mind) that excelled by their good quality and their
These demos consisted of massive datafiles containing digitized
sound data. For about 2 minutes of good quality music, 600 Kb of
memory had to be used - hence the reason that these demos only
worked on 1 Mb machines with a double-sided disk drive.
What exactly is 'digitized music'?
As you all know, sound consists of waves. These can vary from
pure sinuses to rather complex waves that e.g. belong to the
human voice or belong to explosions. There is a way to create
these waves on the ST as well, but therefore the analog sound
information has to be transformed into digital sound information.
This process is called 'digitizing' and the device you need to do
that is a 'digitizer' that usually contains an AD converter
(Analog-digital converter). This digital format is needed because
a computer only 'understands' numbers.
A piece of digitized music is called a 'sample'. Nowadays, the
technique of using samples in music is very common. Drum
computers use sampled drum sounds, and some groups ONLY use
samples (e.g. the Art of Noise and a lot of that current hip hop-
, Acid-and New Beat trash).
It is possible to digitize a piece of music and play it back
through the soundchip. The only register that is used here is the
volume register; playing back digitized sound is in fact just a
controlled version of the noise that would appear if you would
turn the volume of the soundchip to maximum and minimum in a very
But if a piece of music consists of several parts that sound the
same, it is possible to record these separately and play them
back in a specific order. This kind of mixing makes the music
appear to be longer, or allows the programmer to use less memory
This kind of 'mixed' music often appeared in games or demos.
Except for the fact that it takes a lot of processor time to play
digitized music (especially at a high frequency) and other tasks
of a program running the music will be harder to program, using
digitized sound is very easy. That's why I usually dislike
digital music when used in games; it just consumes a lot of space
and is very easy to program (even yours truly could do it).
But there is, as you could have guessed, an even more advanced
way of playing back sampled sounds. This method is sometimes used
by professional sound programmers and was first tried out by
Jochen of The Exceptions in the "B.I.G. Demo".
This way consists of single samples sounds (e.g. a guitar chord,
a bass drum, a flute note, etc.) and storing them in a much more
compact file. When playing them back, you can perform some
complex calculations that play the instrument sample on different
heights, thus obtaining different notes. When you want to make a
song with just a solo guitar, a bass guitar and a single drum,
for example, you would just have to sample ONE guitar note, ONE
bass guitar note and ONE drum sound.
This saves a LOT of memory space, since now you only need three
sounds instead of much larger segments of a song. And if you want
to use different sounds, you simply sample them, too. The program
will then play them back.
But what if you want a DRUM sound and a GUITAR sound to be
audible simultaneously? All the previous methods only played
'with one voice'. Since the ST has three voices, Jochen found out
that it is possible to play back three voices as well, by using
the individual channels.
Now we're getting somewhere. Not only can we now use digitized
music while consuming a great deal less memory, but we can also
use three channels together (in the "Amiga Demo" - March 1988 -
Jochen even uses FOUR channels by adding an extra one to the
third voice's data). Even advanced sound options (transpose and
portamento) are possible using this technique!
The only disadvantage of using three separate voices and
digiti