53279



53279          D01F           CONSOL
     (W/R) Used to see if one of the three yellow console buttons has
     been pressed (not the RESET button!). To clear the register,
     POKE CONSOL with eight. POKEing any number from zero to
     eight will cause a click from the speaker. A FOR-NEXT loop that
     alternately POKEs CONSOL with eight and zero or just zero,
     since the OS put in an 8 every 1/60 second, will produce a buzz.
     Values PEEKed will range from zero to seven according to the
     following table:

     |Key        Value    0    1    2    3    4    5    6    7    |
     |                                                            |
     +------------------------------------------------------------+
     |                                                            |
     |OPTION              X    X    X    X                        |
     |SELECT              X    X              X    X              |
     |START               X         X         X         X         |
     |                                                            |
     +------------------------------------------------------------+
      Bits   2            0    0    0    0    1    1    1    1
             1            0    0    1    1    0    0    1    1
             0            0    1    0    1    0    1    0    1


     Where zero means all keys have been pressed, one means
     OPTION and SELECT have been pressed, etc., to seven, which
     means no keys have been pressed. CONSOL is updated every
     stage two VBLANK procedure with the value eight.

     It is possible to use the console speaker to generate different
     sounds. Here is one idea based on an article in COMPUTE!,
     August 1981:

     10   GOSUB 1000
     20   TEST = USR(1536)
     999  END
     1000 FOR LOOP = 0 TO 26: READ BYTE: P
          OKE 1536 + LOOP, BYTE: NEXT LOOP
          : RETURN
     1010 DATA 104,162,255,169,255,141,31,
          208,169
     1020 DATA 0,160,240,136,208,253,141,3
          1,208,160
     1030 DATA 240,136,208,253,202,208,233
          ,96

     To change the tone, you POKE 1547 and 1555 with a higher or