Int 16 Fn 04  - K3plus V6.22+ - Set Keyclick                               [K]

   AH = 04h
   AL = keyclick state
       00h keyclick off, leave loudness setting unchanged
       01h keyclick on, leave loudness setting unchanged
       else
          bit 0: keyclick enabled if set
          bits 7-1: new keyclick loudness (non-zero)

Return: AH destroyed by many BIOSes

Note:  Applications which try to set a new loudness, but are unsure of the
     results of other INT 16/AH=04h implementations, should set the new
     loudness first, and then call this function again with AL=01h or
     AL=00h

See Also: AH=03h,AH=04h"KEYBOARD",AX=AF4Dh