In the end of the 8 bit generation, musics started using audio samples. Before that music often used generated sounds, like sinus or triangle waves. These songs are also called « chip tunes ». When 16 bits computers arrived, they had enough memory for audio samples to be used. The system of « Tracker » from 8 bits computers was reused and software like « SoundTracker » were created. Not sure it was the first one on Amiga, but it was the first I discovered. Over time, the principle also stayed the same.
Amiga have 4 audio channels (2 left, 2 right).
Here is a video taken from internet, showing how SoundTracker run.
In fact, it is a step sequencer. For each step, you can specify a note played by one sample, and/or effect to be applied. There was volume effect, vibratos, speed, and lot of others. Effect have been really used a bit later.
The first version of SoundTracker also came with sample disk. They where called « ST-XX ». ST-00 was the first. The music you are earing on the video surely use samples from the ST-00 disk.
The big advantage of using trackers is that software also came with Assembly « replay » routine. To play a music from your game/intro/demo you only had to include the source code of the player and call it from your program. It was magic!
Waveforms trackers (chiptune music) also existed on Amiga. I was using « Futur composer ». It looks the same as a wave tracker, but use synthetic sounds.
Here is a video taken from net showing how futur composer runs:
You can listen to FC music on windows, using for example one software done by a friend of mine: ST-SOUND by Leonard/Oxygen. Web site here : http://leonard.oxg.free.fr/ You can also use winamp plugin « Oldsk00l MOD player ».
The big advantage of these musics is that they were very small (in bytes size).