Sound: BDlab6

       Name: BDlab6                                                  [Show more]
       Type: Subroutine
   Category: Sound
    Summary: Set the voice control register for voice 2 to value2
    Context: See this subroutine in context in the source code
 References: This subroutine is called as follows:
             * BDRO2 calls BDlab6
             * BDRO4 calls BDlab6
             * BDRO5 calls BDlab6


.BDlab6

 LDA value2             ; Set A to value2, to use as the new value of the voice
                        ; control register for voice 2

 STY SID+$B             ; Zero SID register $B (the voice control register for
                        ; voice 2), to reset the voice control

 STA SID+$B             ; Set SID register $B (the voice control register for
                        ; voice 2) to the music data byte that we just fetched
                        ; in A, so control the voice as follows:
                        ;
                        ;   * Bit 0: 0 = voice off, release cycle
                        ;            1 = voice on, attack-decay-sustain cycle
                        ;
                        ;   * Bit 1 set = synchronization enabled
                        ;
                        ;   * Bit 2 set = ring modulation enabled
                        ;
                        ;   * Bit 3 set = disable voice, reset noise generator
                        ;
                        ;   * Bit 4 set = triangle waveform enabled
                        ;
                        ;   * Bit 5 set = saw waveform enabled
                        ;
                        ;   * Bit 6 set = square waveform enabled
                        ;
                        ;   * Bit 7 set = noise waveform enabled

 RTS                    ; Return from the subroutine