53762



     Bit   7   6   5      4     3   2   1   0
          Distortion   Volume      Volume
            (noise)     only        level
           0   0   0      0     0   0   0   0   Lowest
           0   0   1            0   0   0   1
            etc. to:             etc. to:
           1   1   1      1     1   1   1   1   Highest
                       (forced
                       output)

     The values for the distortion bits are as follows. The first process is
     to divide the clock value by the frequency, then mask the output
     using the polys in the order below. Finally, the result is divided by
     two.

     Bit
     7    6    5
     0    0    0  five bit, then 17 bit, polys
     0    0    1  five bit poly only
     0    1    0  five bit, then four bit, polys
     0    1    1  five bit poly only
     1    0    0  l7 bit poly only
     1    0    1  no poly counters (pure tone)
     1    1    0  four bit poly only
     1    1    1  no poly counters (pure tone)

     In general, the tones become more regular (a recognizable
     droning becomes apparent) with fewer and lower value polys
     masking the output. This is all the more obvious at low frequency
     ranges. POKE with 160 ($A0) or 224 ($E0) plus the volume for pure
     tones.

     See De Re Atari and the Hardware Manual for details.

                              POT1 
     (R) Pot 1 register (625).

53762          D202           AUDF2
     (W) Audio channel two frequency. Also used with AUDF3 to store
     the 19200 baud rate for SIO.

                              POT2
     (R) Pot 2 (626).

53763          D203           AUDC2
     (W) Audio channel two control.

                              POT3
     (R) Pot 3 (627).