ntropic - ZX Spectrum beeper music engine
written by utz 01'14
1tracker version by Shiru, 2014


A simple engine that provides two channels of square tone with detune 
support, similar to the Music Box engine, one channel of white noise 
with fixed pitch but variable duration, and one type of interrupting 
click drum. 

The columns are:

T1 d T2 d Ns D
.... .... .. .

T1,T2 : Tone channels
 Tn : Note, F#1..B-7
  d : Detune, 1..9

Ns : Noise duration
 D : Drum
