Retreive The Current Drive Letter
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 Syntax

        GT_CURDRIVE()

 Arguments:

      None

 Returns:

      The Driver Letter Of The Current Drive

 Description:

      Calls function 19h (25) of interupt 21h (33) using GT_INT86()

 Examples:

      cDrive := GT_CURDRIVE()

 Source: GT_CURDR.PRG

 Author:  Allen Bullen