1.1. Halfword overflow (continued) – Brian Randell's initial post to Risks

posted Sep 14, 2010, 11:47 AM by Jeff Ogden   [ updated Dec 25, 2011, 9:17 PM ]
I found the following.  I think it is Brian Randell's initial post to Risks about this event. It is still hard to figure out what, if anything, crashed and if the crash or other problem actually occurred on both sides of the Atlantic or if the warning from the UK came soon enough to save the rest of us some embarrassment. The post talks about an "unexpected system shutdown" and a "bug", but doesn't use the word "crash".

From the Risks Digest, Volume 9, Number 45, 20 November 1989:

Another foretaste of the Millenium

Brian Randell <Brian.Randell@newcastle.ac.uk>
Fri, 17 Nov 89 9:17:33 BST
We apologise for the unexpected system shutdown today (Thursday).  This was
caused by a bug in the MTS system that was a "time-bomb" in all senses of the
word. It was triggered by today's date, 16th November 1989.

This date is specially significant. Dates within the file system are stored as
half-word (16 bit) values which are the number of days since the 1st March
1900. The value of today's date is 32,768 decimal (X'8000' hexadecimal). This
number is exactly 1 more than the largest positive integer that can be stored
in a half-word (the left-most bit is the sign bit). As a result, various range
checks that are performed on these dates began to fail when the date reached
this value.

The problem has a particular interest because all the MTS sites world-wide are
similarly affected. Durham and Newcastle were the first to experience the bug
because of time zone differences and we were the first to fix it.  The American
and Canadian MTS installations are some 4 to 8 hours behind us so the
opportunity to be the first MTS site to fix such a serious problem has been
some consolation.  The work was done by our MTS specialist who struggled in
from his sick bed to have just that satisfaction!
Does anyone remember who the "MTS specialist" was?

And a little more from the next Risks digest, Volume 9, Number 46, 22 November 1986. PNG is the risks moderator Peter G. Neumann.

Another Foretaste of the Millenium? (RISKS-9.45, corrigenda)

Brian Randell <Brian.Randell@newcastle.ac.uk>
Tue, 21 Nov 89 10:12:20 BST
   [Brian sent me two versions of the MTS saga, part of one of which ran in
   RISKS-9.45 -- but without the explanation indicating that the MTS message
   was not from Brian but rather from someone else.  The surrounding text is
   given below, in case anyone thought that the "We apologise ..." message
   was originally Brian's.  I apology to Brian in case anyone was misled.  PGN]

The university computing service here runs MTS (the Michigan Terminal System)
on an Amdahl mainframe, which crashed mysteriously today, as did various other
MTS sites in North America, some time later. The explanation is given in the
following message which I have just received from one of the systems
programmers here.

> We apologise for the unexpected system shutdown ... [see RISKS.9-45 for text.]

I hadn't realised that there was this disadvantage to living on this side of
the Atlantic! Ah, well, it makes up for various advantages :-)

Brian Randell

This note does use the word "crash" and says that there were problems on both sides of the Atlantic.

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