JOYSTICKS

The ports assigned to joysticks are:

#7F    Fuller Box  (FxxxRLDU, active low)
#1F    Kempston    (000FUDLR, active high)
#EFFE  Sinclair1   (000LRDUF, active low, corresponds to keys '6' to '0')
#F7FE  Sinclair2   (000FUDRL, active low, corresponds to keys '1' to '5')

The TS2068 is slightly more complicated, as the joysticks attached to R14
of sound chip; the following code is typical for reading the joysticks:

  LD A,7
  OUT (#F5),A   ;set R7
  IN A,(#F6)
  AND #BF       ;clear bit 6 to read from i/o port a - R14
  OUT (#F6),A
  LD A,14
  OUT (#F5),A   ;set R14
  LD A,3        ;(3=both joysticks, 2=left only, 1=right only)
  IN A,(#F6)    ;(FxxxRLDU, active low)

This method ensures other sound chip functions aren't messed with.