    CORE(V)                      2/11/75                      CORE(V)

    NAME
         core - format of core image file

    DESCRIPTION
         UNIX  writes  out  a core image of a terminated process when
         any of various errors occur.  See signal(II) for  the  list
         of  reasons;  the most common are memory violations, illegal
         instructions, bus errors, and user-generated  quit  signals.
         The core image is called ``core'' and is written in the pro-
         cess's working directory (provided it can be; normal  access
         controls apply).

         The  first  1024  bytes  of the core image are a copy of the
         system's per-user data for the process, including the regis-
         ters  as  they were at the time of the fault.  The remainder
         represents the actual contents of the user's core area  when
         the  core  image was written.  If the text segment is write-
         protected and shared, it is not dumped; otherwise the entire
         address space is dumped.

         The format of the information in the first 1024 bytes is de-
         scribed by the user structure of the system.  The  important
         stuff  not  detailed  therein is the locations of the regis-
         ters.  Here are their offsets.   The  parenthesized  numbers
         for  the  floating  registers are used if the floating-point
         hardware is in single precision mode, as  indicated  in  the
         status register.

            fpsr   0004
            fr0    0006  (0006)
            fr1    0036  (0022)
            fr2    0046  (0026)
            fr3    0056  (0032)
            fr4    0016  (0012)
            fr5    0026  (0016)
            r0     1772
            r1     1766
            r2     1750
            r3     1752
            r4     1754
            r5     1756
            sp     1764
            pc     1774
            ps     1776

         In  general  the debuggers db(I) and cdb(I) are sufficient
         to deal with core images.

    SEE ALSO
         cdb(I), db(I), signal(II)

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