Source : Free On-Line Dictionary of Computing

dusty deck
     
        Old software (especially applications) which one is obliged to
        remain compatible with, or to maintain.  {DP} types call this
        "legacy code", a term hackers consider smarmy and excessively
        reverent.  The term implies that the software in question is a
        holdover from card-punch days.  Used especially when referring
        to old scientific and {number crunching} software, much of
        which was written in Fortran and very poorly documented but is
        believed to be too expensive to replace.  See {fossil};
        compare {crawling horror}.
     
        [{Jargon File}]