資料來源 : Free On-Line Dictionary of Computing

casters-up mode
     
        [IBM, probably from slang belly up] Yet another synonym for
        "broken" or "down".  Usually connotes a major failure.  A
        system (hardware or software) which is "down" may be already
        being restarted before the failure is noticed, whereas one
        which is "casters up" is usually a good excuse to take the
        rest of the day off (as long as you're not responsible for
        fixing it).
     
        [{Jargon File}]