vi core dumping on Sun 2 (fixed, but would like explanations)

[William P. Malloy]

We ran into a rather odd little problem here a few days ago.  And would like
someone elses opinion.

SYSTEM description:
	Sun 2/170  running Sun release 1.2 (4.2bsd binary)
	4 Meg memory
	1 Xylogics 450 SMD disk controller
	1 Eagle (Fujitsu M 2351A) disk drive
	1 SKY FPA
	1 3COM Ethernet board
	1 Systech Terminal Mux (16 ports) 
In short a small 16 user computer with virtual memory and a big disk.

Problem Description:
	vi dumps core, repeatedly and reliably.  I.e. it doesn't work.

How it started:
Someone here had just ignored the old saying about not trying to fix that
which is not broken,  and had just rebooted all our Sun 2/170's (in order to
force fsck to check the disks) when the problem started (vi core dumping).

NOTE the following:
1) Binary hadn't been modified at all since pulled off the Sun release tape.
2) Rcp-ed vi from another Sun over ethernet and did a ``cmp'' on the two
   binarys and noted they were EXACTLY the same.
3) Tried running the vi binary from the other Sun, noted it works FINE.
4) Tried copying the vi binary to another file, works FINE.
5) Get clever.  Notice vi has 6 links, make 5 links to the other Suns vi and
   run it.  Works FINE.
6) Get cleverer still.  Notice vi has sticky bit turned on, so turn on the
   sticky bit of the other vi, try that.  Works FINE.
7) Rebooted system, problem goes away.      <************* NOTE *************

Needless to say we were ANNOYED.  The only thing worse then a bug, is a non-
repeatable bug.  And the only thing worse than that is a repeatable, but
incomprehensible one.  The only thing I can think of is that vi (perhaps
because of the sticky bit) had been loaded into memory and retained there
by UNIX.  And some location in memory where vi had been put was BAD.  Sun is
well known for having memory problems.  However we had no Memory errors in
our /usr/adm/messages file (at least none recently).

Anybody out there want to guess at another explanation.  It's not to important
so long is it doesn't repeat itself, but it is ODD.

BTW To people who have Suns. In section 8 of the manual Sun has a standalone
command called ``imemtest'' which is supposed to run a memory testing routine.
The man page says it's interactive and self-explanatory.  Well it doesn't work
for me.  Anyone ever get this to work (or is it just some nonsense from Sun
that is best deleted?)
-- 
Address: William P. Malloy, ITT Telecom, B & CC Engineering Group, Raleigh NC
         {ihnp4!mcnc, burl, ncsu, decvax!ittvax}!ittral!malloy