MOD music is generated by mixing different instrument sounds in realtime, following a sequenced song pattern. The instrument sounds are digitised waveforms, called samples, while the song is split up into pattern blocks, the same way sheet music is divided into bars.
MOD's originated on the good old Amiga, which had a sound chip ("Paula") capable of playing 4 channels of 8-bit digitised sound, independant of the CPU. The poor PC, however, has no such luxury - all the mixing of samples must be done by the CPU.
Recommended Trackers:
ModPlug Tracker
Some of my MOD's (mostly just experiments or background for videogames):
Some of Kline's MOD's:
Go to Kline the ModMeister's Page for more of his groovy music.
Links to Tracker and MOD sites:
Some of my MIDI songs (best played thru GM or AWE32):