Y2K and immortal executables

From: John Ruschmeyer <jruschme_at_exit109.com>
Date: Thu Oct 22 15:51:25 1998

> But aren't there many machines that keep track of time and date? I've
> heard that credit cards are starting to fail if their expiration date
> is 2000. I don't know why all the fuss about the control tower
> computers or power plants (all scheduling should be doublechecked by
> humans anyway), but I'm sure there may be problems with checks/bills.

The problem, as I understand it, is that there are a lot of embedded
computers which do date-related calculations that you'd never think of.

An example was given on one of the Usenet news groups of an embedded
system which controlled the outflow valve of a sewer pipe. It apparently
operated by calculating high tide times based on an internal clock/
calendar. It failed Y2K testing.

Now think of the results, had this happened "live". Raw sewage dumped at
(potentially) low tide. A mess, if not a health hazard.

More on-topic is the so-called "Time Dilation Effect" or "Echelin-Crouse
Effect" which has been documented on older (and some not-so-old) PCs.
Basically, it shows itself as a clock which seemingly jumps ahead on
some post-1/1/2000 reboots. Over a few weeks, the clock appears to gain
several months of time. In some cases, the system may then stop booting
or lose track of ports until the clock is set back to before 1/1/2000.

The root cause has been traced to unbuffered real-time clock chips. On
a system with such a chip, the BIOS may attempt to read some data during
a time when it is being updated and during which a flag value is present,
instead of a real date. It only seems to occur post-1/1/2000 because the
longer code path taken to calculate the Y2K date may take longer than the
grace period the clock chip provides prior to an update.

Messy stuff...
<<<John>>>
Received on Thu Oct 22 1998 - 15:51:25 BST