Msg: 6001 *Conference*

08-31-95 10:04:09

From: TRACY ALLEN

To : RON WIESEN

Subj: REPLY TO MSG #5972 (UNDELETE -- COLD START RECOVERY)

Ron,
  Sometimes out-of-control m/l programs get into a loop where they write just
about any pattern you could think of into RAM, before eventually cold starting.
They don't have to cold start, of course, if they just get caught in a loop
that never disturbs one of the areas that gets tested for memory corruption
during startup. A bad m/l program can write every Nth byte into memory, or it
could write at random locations, or it could put nulls in every location, or it
could write a repeating pattern, or once every million years, it could even
randomly write in the text of Hamlet.  The bad thing is, it is impossible then
to recover what had been in memory before the incident.  The good news is that
ususally bad m/l programs or whatever cold starts don't do anything at all to
the original contents of memory.  I had the code of the cold start test routine
printed out somewhere, but I can't locate the printout at the moment.  Chris
Morgan's book is in error (page 80) when it calls the routine at 6CD6 the cold
start routine.  That is really just INITIO, which clears the i/o buffers in
high memory.
  -- Tracy