Int 16 Fn 20  O - K3 V1.5x, K3plus V5.xx - Get Extended Buffer State       [K]

   AH = 20h

Return: AX = K3 version
   ES:BX -> extended keyboard buffer start
   ES:DX -> extended keyboard buffer end
   ES:SI -> next keystroke
   ES:DI -> last keystroke in buffer
   CX = number of keystrokes in buffer
Program: K3PLUS is an extended keyboard driver by Matthias Paul and Axel C.
     Frinke, originally based on the K3 extended German keyboard driver
     by Martin Gerdes published in c't magazine in 1988

Note:  this function was normally unsupported under K3PLUS v6.00-v6.22 and
     is no longer supported by v6.30+; use AX=AF20h instead

See Also: AH=25h"K3",AX=AF20h,INT 2F/AX=D44Fh/BX=0000h,INT 2F/AX=ED58h