Int 21 Fn 2B  - Volkov Commander - Installation Check                      [l]

   AH = 2Bh
   CX = 5643h ('VC')
   DX = 4F4Dh ('OM')
   AL = function number
       00h get left window data address
       01h get right window data address
       02h get address of general variables

Return: AL = 00h if Volkov Commander installed
       AH = version code (27h for v4.00.039)
       ES:BX -> requested data
Program: Volkov Commander is a Norton Commander-like DOS shell