Int 2F Fn DF00  U - Quarterdeck Teltsr.com - Installation Check            [Q]

   AX = DF00h
   BX = 5445h ('TE')
   CX = 4C54h ('LT')
   DX = 5352h ('SR')

Return: BX = 5454h ('TT') if installed
   CX = 494Eh ('IN') if installed
   DX = 5454h ('ST') if installed
Program: TELTSR is a Telnet TSR included with Quarterdeck's DESQview/X v2.00
     which provides an INT 14h interface to the network
Range: AH=DEh to AH=FFh and AH=C0h to AH=DDh, selected by scanning

See Also: AX=DF01h"TELTSR",AX=DF02h"TELTSR",INT 14/AH=56h