Audio info continued

Just a quick run down of the top two bits of $804. A small part of a large audio doc.


0x804
  -----
  
    D7
    --
        value=1
          
              A)  Allows audio output to the DAC.
              B)  Writes to data port and waveform buffer playback 
                  output to the DAC.
              C)  Allow underflow from period counter to clock the waveform
                  pointer.
              D)  Data port writes output to the DAC *and* transfer/replace
                  the waveform memory at the current pointer position.
              E)  Waveform memory pointer is not clocked by data port
                  writes.
        
        value=0
        
              A)  Stops all audio from outputting to the DAC.
              B)  Writes to the data port store in the waveform memory and
                  clock the waveform memory pointer.
              C)  Period counter is paused and does not clock the waveform
                  memory pointer. The counter is *not* reset/re-initialized.
                  
    D6
    --
        value=1
                  
              A)  Waveform memory pointer is reset to $00.
              B)  Period counter is reset and halted/turned off.
              C)  Waveform memory pointer is locked and not clockable.
              D)  Writes to the data port do not transfer to the waveform
                  memory.
              
        value=0
                  
              A)  Waveform memory pointer is clockable.
              B)  Data port writes trasnfer to the waveform memory.
              C)  Period counter is not halted/off.
              
    D7-6
    ----
      
        00b:  Audio output is disabled. Period counter is paused. Data port
              writes transfer to waveform memory. Waveform memory pointer
              is clocked only by data port writes.

        01b:  Audio output is disabled. Period counter is halted and reset.
              Data port writes do not transfer to waveform memory. 
              Waveform memory is not clocked by either data port writes or
              period counter.
              
        10b:  Audio output is enabled. Period counter underflow clocks 
              waveform memory pointer. Data port writes output to the DAC
              and trasnfer into waveform memory. Data port writes do not 
              clock the waveform memory pointer.
              
        11b:  Audio output is enabled. Period counter is halted and reset.
              Data port writes do not transfer to waveform memory. Waveform
              memory pointer is not clocked by data port writes or period
              counter.
              
              
     Note: Transition from 10b to 00b clocks the waveform memory pointer.
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