Int 21 Fn 30FF  - Desq??? - Installation Check                             [-]

   AX = 30FFh
   CX = 4445h ("DE")
   DX = 5351h ("SQ")

Return: BH = 05h if installed
   ???

Note:  called by DUBLDISK.COM v2.6; this function is not supported by
     DESQview, so it may be for DESQview's precursor DESQ.

See Also: AX=4404h"DUBLDISK"