NAME
   ReadUnitID - reread and return the type of drive (V37)
SYNOPSIS
   idtype = ReadUnitID( unitNum ), DRResource
    D0                     D0         A6
    ULONG ReadUnitID(LONG);
FUNCTION
    Rereads the drive id for a specific unit (for handling drives
    that change ID according to what sort of disk is in them.  You
    MUST have done a getunit before calling this function!
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
    getunitid
BUGS