53764



53764          D204           AUDF3
     (W) Audio channel three frequency. Used with AUDF3 above and
     with AUDF4 to store the 600 baud rate for SIO.

                              POT4
     (R) Pot 4 (628).

53765          D205           AUDC3
     (W) Audio channel three control.

                              POT5
     (R) Pot 5 (629).

53766          D206           AUDF4
     (W) Audio channel four frequency.

                              POT6
     (R) Pot 6 (630).

53767          D207           AUDC4
     (W) Audio channel four control.

                              POT7
     (R) Pot 7 (631).

53768          D208           AUDCTL
     (W) Audio control. To properly initialize the POKEY sound
     capabilities, POKE AUDCTL with zero and POKE 53775,3
     ($D20F). These two are the equivalent of the BASIC statement
     SOUND 0,0,0,0. AUDCTL is the option byte which affects all
     sound channels. This bit assignment is:

     Bit    Description:
     7      Makes the 17 bit poly counter into nine bit poly
            (see below)
     6      Clock channel one with 1.79 MHz
     5      Clock channel three with 1.79 MHz
     4      Join channels two and one (16 bit)
     3      Join channels four and three (16 bit)
     2      Insert high pass filter into channel one, clocked by channel
            two
     1      Insert high pass filter into channel two, clocked by channel
            four
     0      Switch main clock base from 64 KHz to 15 KHz

     Poly (polynomial) counters are used as a source of random pulses
     for noise generation. There are three polys: four, five and 17 bits
     long. The shorter polys create repeatable sound patterns, while the
     longer poly has no apparent repetition. Therefore, setting BIT 7
     above, making the 17-bit into a nine-bit poly will make the pattern