Int 16 Fn 55FE  CU - Microsoft Qbasic Internal - Microsoft Cooperation Wi  [A]

   AX = 55FEh
   DX = function
       0000h initialize
       ES:BX -> ??? function
       ES:CX -> ??? structure
       FFFFh shutdown/reset

Return: AX = result
       4D4Bh only the INT 1B handler will be installed.
       other: handlers for INT 08, INT 09, INT 16, INT 1B, and INT 1C
         are installed

Notes: The pointer in ES:CX seems to point at a structure defining a callback
     function when new keyboard keys are pressed. If a TSR returns
     AX=4D4Bh, QBASIC will stop (with IRQ's and interrupts enabled).
   these calls are also made by MS-DOS 6.0's DOSSHELL at startup, exit,
     and before/after shelling out
   since EDIT.COM and HELP.COM merely invoke QBASIC, those two programs
     will also cause this interface to be invoked
   K3PLUS v6.07+ supports this function, but will never invoke the
     callback function

See Also: AX=5500h,AX=AF4Dh,INT 1A/AX=3601h