Q About six months ago I purchased a Compaq Presario 5630. The salesman assured me that it was Y2K compliant, but I decided to test it myself. First I ran NSTL's YMark2000, and the PC passed with flying colours. Then I tried Safetynet's Yes2K, and my Compaq failed the CMOS test. Is my system Y2K compliant?

A Two pieces of PC hardware deal with time and date: BIOS code and the CMOS clock/calendar. The CMOS chip's battery lets it track the time and date even when your system is turned off. When you boot your PC, the BIOS chip's start-up routines make the time and date stored in the CMOS chip available to your software.

Few CMOS chips are smart enough to roll over into the next century on their own. That's why your PC failed Yes2K's CMOS test. But a Y2K-ready BIOS will treat a CMOS date in 1900 as an error and correct it. So the CMOS test is relevant only if you have software that reads the date directly from the CMOS chip.

Luckily, very few programs read the date directly from the CMOS. One of the handful of exceptions is Safetynet's StopLight, and even it consults the BIOS if the CMOS date looks suspect. I have yet to hear of a Windows business application that draws the wrong century from the CMOS when the BIOS presents it with the right one.

So even if your new Presario can't pass every test you give it, it has passed the ones that count. Nonetheless, getting PC hardware to function properly is the easy part of the year 2000 problem. The hard part is dealing with badly entered and transferred data, and handling small-market and custom-built programs.