In message <E1Dyp42-0008Vp-00_at_mta1.cl.cam.ac.uk>, Markus Kuhn writes:
>> And in 2003, a leap-second
>> bug made GPS receivers from Motorola Inc. briefly show customers the
>> time as half past 62 o'clock.
>
>It conveniently omits the minor detail that this long preannounced
>Motorola software bug actually manifested itself on 27 November 2003
>and was not in any way caused by an added leap second, but by an
>unwise design choice in the GPS data format and a resulting counter
>overflow.
Obviously, if leapseconds hadn't existed in the first place, this
bug would not have happened, because Motorola would not have included
the buggy code in the receiver.
And it is a very good example of exactly the kind of computer problem
leap seconds give rise to: code that only gets executed once in a
blue while, but not often enough to allow manufacturers to test it
comprehensively before shipping products.
>and was later only slightly elaborated by Peterson in
>
> http://www.maa.org/mathland/mathland_7_21.html
>
>where he admits that he "never could find out precisely why the
>problem had occurred and who was responsible for it".
Again, another good example of the computer problems leapseconds
causes: If something goes wrong with leapsecond handling, you have
to wait an indeterminate amount of time before you can get to see
if you have managed to fix the problem or to collect more diagnostic
information.
--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
phk_at_FreeBSD.ORG | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
Received on Sat Jul 30 2005 - 07:44:51 PDT