|
Most everyone knows, by now, about the Year 2000 bug and how it will
affect PC’s. We all know that we must prepare our PC’s for the year 2000,
and once that problem is fixed we’ll all be just fine right? Wrong! Researchers
have discovered a new glitch that won’t rear it’s ugly head until after
the turn of the century. Like all the most notorious glitches it’s appearances
will be sporadic, unpredictable, and accompanied by selective chaos and
mayhem. The glitch is called the Crouch-Echlin Effect, after it’s discoverers
Jace Crouch and Mike Echlin. If you want to look up their story a search
of "Crouch-Echlin" on the web will keep you busy for quite a while. This
glitch will affect new machines and old, big systems as well as desk tops.
An equal opportunity problem, you might say.
In a nutshell, Crouch-Echlin causes the computer, every once in a while, to power up with a bogus date, but it will only do this if the computer’s date is greater than 1999. To explain why, we must get just a little bit technical. The problem involves the master clock chip on the computer’s motherboard, called the Real Time Clock (RTC). It also involves the BIOS (Basic Input-Output System), those hard wired instructions the computer uses when it first boots up (turns on), that give it enough wits to go fetch it’s Operating System from the hard disk. One of the things the BIOS does on start-up is to read the current date and time from the RTC, and store it in a certain memory location where the Operating System can retrieve it. Back in 1980 when the Personal Computer was invented, the BIOS programmers apparently realized we were at the beginning of a new era. Just as our calendar is measured in the number of years BC (Before Christ), the BIOS figures it’s dates by the number of years since 1980. We can call this "BB", for Before Bill (Gates) if you like. So far, this has been an easy calculation for the BIOS to make; just subtract 80 from the last two digits of the date. The BIOS manufacturers were among the first to realize they had a Y2K problem, because this calculation obviously doesn’t work for dates 2000 and higher. They’ve had to add a little detour to the start-up routine, which says "If the date is less than 2000, subtract 80 but if greater than 2000 go to the new 4 digit date routine." Which brings us to the second part of the Y2K problem. The RTC updates itself once every second, and while it’s updating, the date and time output from the chip is changing, and therefore is in an undetermined state. This is not a good time for the BIOS to sample the date and time. Fortunately, the RTC has a little flag signal that says "I’m changing. Don’t read me yet." The flag actually comes on 244 microseconds before the outputs change, so the BIOS has a little cushion of time to decide whether to take the sample right then, or to wait and try again. Now, when the BIOS only had to subtract 80 to calculate the date, the whole operation took less than 244 microseconds, which is why the Crouch-Echlin effect didn’t show up in this century. When the BIOS must go into its ‘new 4 digit date routine’ it takes a little longer than 244 microseconds, which is usually OK. Every once in a while though, the BIOS will happen to check the RTC’s flag just a few microseconds before it changes. It thinks everything is fine, but by the time it gets done calculating, the RTC outputs are in a state of flux, and the BIOS comes away with garbage. Voila, the Operating System starts up with a phony date and time. Should you be losing sleep over this? Well, there are cures for the problem. The most basic would be to change the way the BIOS calculates dates (don’t hold your breath on this one). A much better, and more accurate cure would be to use an RTC chip that has a double-buffered output. With a double-buffered output there is no danger of the outputs changing state while they are being sampled. Unfortunately, Crouch-Echlin is a recent discovery, and most motherboards are still being designed with un-buffered RTC’s. If you thought your new Pentium system with Windows 98 was immune to Y2K problems, guess again. Another solution is to manually check your system date every time you power up. You can change the date if needed, and it will stay accurate as long as the computer stays on, because Crouch-Echlin only occurs on boot-up. A bit of a nuisance, but it will work in most applications. You only need to do it for the next hundred years (just kidding). The easiest solution for a PC owner is to install a Centurion card into the system. This 8 bit card fits into any vacant ISA or EISA slot on the motherboard, and its own double-buffered RTC takes over from the motherboard’s clock. This not only handles the normal Y2K hardware problems, it cures Crouch-Echlin almost as an afterthought. And it couldn’t be easier. Just plug it in and forget it for the next ten to thirty years. Although there are several Y2K solution cards on the market, only Centurion uses a double-buffered RTC. The irony is that by installing one of the other cards, you could actually introduce Crouch-Echlin into a system that didn’t originally have it. So, now you know. If you would like to find out if your system is prone to the Crouch-Echlin Effect or other Y2K problems, you can download free testing software by clicking on the "test" button. You can find more information on the Crouch-Echlin Effect on our Y2K Links page. We have links to the most up to date information on all Y2K problems including links to Jace Crouch and Mike Echlin's web sites. For other information about the Centurion or the Y2K problem click on the contact button to find out how to reach us. |
