This instruction is available in MSX-AUDIO Basic and MSX-MUSIC Basic.
Transposes in units of half tones the FM sounds (melody and rhythme) generated by the FM generator(s). It can be set independently of the pitch parameter.
This instruction is without effect on PCM and PSG.
CALL TRANSPOSE(<transpose generator 1>[,<transpose generator 2])
<transpose generator 1> and <transpose generator 2> specify a value between -12799 tot 12799. The unit is 1/100. The extreme values are approximative due to hardware limitations.
After initialization with CALL AUDIO or CALL MUSIC, the value is 0. To increase one octave, specify +1200. To decrease one octave, specify -1200.
When using MSX-MUSIC, <transpose generator 2> is ignored even if there are two MSX-MUSIC chips (internal and external for example), because all the MSX-MUSIC chips use only the Z80/R800 ports 7C-7D without possibility of alternative ports.
When using MSX-AUDIO, both parameters are taken in account when two MSX-AUDIO chips are used simultaneously by the MSX computer (using different Z80/R800 ports: C0-C1 for the first FM generator, C2-C3 for the second FM generator). If only the first parameter is specified in such situation, it will be applied to both FM generators.
10 CALL AUDIO 20 CALL TRANSPOSE(0,700)