NAME
       GetUnitID - find out what type of disk is out there

   SYNOPSIS
       idtype = GetUnitID( unitNum ), DRResource
        D0                  D0         A6

        long getunitid(long);

   FUNCTION
        Gets the drive ID for a given unit.  Note that this value may
        change if someone calls readunitid, and the drive id changes.

   INPUTS
        unitNum -- a legal unit number (zero through three)

   RESULTS
        idtype -- the type of the disk drive.  Standard types are
                defined in the resource include file.

   EXCEPTIONS

   SEE ALSO
        readunitid()

   BUGS