Changes
/* Writing to a PSG register */
.write_to_psg
ld b,&f4 ;} setup PSG register number on PPI port Aout (c),c ;}
ld bc,&f6c0 ;} Tell PSG to select register from data on PPI port Aout (c),c ;}
ld bc,&f600 ;} Put PSG into inactive state.out (c),c ;}
ld b,&f4 ;} setup register data on PPI port Aout (c),a ;}
ld bc,&f680 ;} Tell PSG to write data on PPI port A into selected registerout (c),c ;}
ld bc,&f600 ;} Put PSG into inactive stateout (c),c ;}
ret
</pre>
