Source : Free On-Line Dictionary of Computing

high moby
     
        /hi:' mohb'ee/ The high half of a 512K {PDP-10}'s physical
        address space; the other half was of course the low moby.
        This usage has been generalised in a way that has outlasted
        the {PDP-10}; for example, at the 1990 Washington D.C.  Area
        Science Fiction Conclave (Disclave), when a miscommunication
        resulted in two separate wakes being held in commemoration of
        the shutdown of MIT's last {ITS} machines, the one on the
        upper floor was dubbed the "high moby" and the other the "low
        moby".  All parties involved {grok}ked this instantly.  See
        {moby}.
     
        [{Jargon File}]