Cruiser:
<<Can someone give a plausible technical explanation why valve controllers and other embedded devices have any use for the year in controlling the device?>>
This is from a conversation I had in 1997 with John Hiles, CEO of Thinking Tools. It still holds.
Virtually any embedded chip that measures a process (heat, temperature, pressure) by taking a measurement at a given interval has a potential (potential!) Y2k problem.
Let's say that you have an analog thermostat which uses mercury to indicate a change in temperature. Remember, a thermostat does not care about absolute temperature - just change over time. The mercury is a perfect analog of the change itself - it expands and contracts over time.
In a digital thermostat, you need two measurements - the absolute temperature and a given interval. Let's say that the temperature was 72 degrees at 99/12/29/11/03/59 and then is 71 degrees at 99/12/29/11/04/19. The chip does a comparison and notes the change.
If the manufacturer has used the unfortunate strategy of using a two digit year in this measurement, and has put it first, the equation can give a negative result, cause the chip to blow up at midnight on January 1 and essentially indicate no change for a pretty darn long period of time. Long enough for blood gas measurements to put patient's lives at risks, long enough for heat measurements to turn off air conditioning systems in coal generated power plants, long enough for pipelines to blow, etc.
Do all digital interval processing control chips use dates? - pretty much. Do they all take the dates out to the year? - no. Do the ones that take it out to the year all use a two digit year? - no. Do the ones that use a two digit year all put the year first? - no.
But there are billions, perhaps trillions of these chips out there. And there is precious little standardization. And many of them are inaccessible.
Christine |
