ZX-7 - ZX Spectrum beeper music engine
Original Z80 code by Jan Deak, 1988
Disassembled by XXL, circa 2009
1tracker version by Shiru, 08'15


The first ever 8-channel ZX Spectrum 1-bit music engine, written by Jean 
Deak in 1988, and released along with ZX-7 Music Composer in 1990. It 
has global speed, loop support. No drums, no detune, just eight notes 
per row. The engine is also one of the rare kind that uses pretty large 
RAM buffer to precalculate sound output for current row. This makes it 
not very usable in games or other software because of heavy RAM usage, 
also limiting the slowest tempo, as slower tempos needs larger buffer. 


The columns are:

T1  T2  T3  T4  T5  T6  T7  T8
... ... ... ... ... ... ... ...
| | | | | | | | | | | | | | | | 
ch1 ch2 ch3 ch4 ch5 ch6 ch7 ch8

T1-T8 : Note, D-1..G#5
