Most RTC date problems are limited to older PCs

Practically every real-time clock in-side a PC or server today is ticking away the
years in two digits. But LAN administrators and users running Microsoft Windows NT need
not worry about RTC misbehavior as they make their year 2000 checks and upgrades.

Users running Windows 95 and Windows 98 will enjoy a reprieve until 2001 rolls around.

Any system with an Intel Pentium, Pentium Pro, Pentium II, Xeon or Celeron processor
stands a good chance of being year 2000-ready or of having a fix available.

All versions of NT, including 3.51 and 4.0, correct RTC errors directly in the system
hardware settings, said Charles Cephas, a Microsoft year 2000 technology specialist.
Windows 9x can compensate for an erroneous year date throughout 2000, he said, but when
2001 arrives, Windows 9x may interpret it as 1901.

Many users are just discovering that computers with Intel Corp. processors have
two-digit RTCs [GCN, Nov. 23, Page 48]. Many experts
recommend, however, that users ignore the RTCs and concentrate on fixing their system
BIOSes instead.

The RTC has been a component of the CMOS chip inside almost every PC since IBM Corp.
built its PC AT 15 years ago. The complementary metal-oxide semiconductor chip on the
motherboard contains the century information, located inside memory register 32. Neither
IBM nor the PC makers that followed it ever intended for the RTC to become the source of
century data.

“We haven’t changed the design [of the RTC] from when it was
introduced,” said Doug Steffen of Intel’s PC motherboard team. “We have
remained backward-compatible with the PC industry standard.”

Intel began integrating real-time clocks into motherboards in 1996, beginning with the
430TX chip set for desktop and mobile Pentiums.

Last week, Intel posted more data about RTC issues on the Web at

CMOS memory holds all the data provided by the BIOS, or basic input/output system,
which bridges the computer’s hardware and software. Time information can reside in
three locations:

Software applications have the option of asking either the operating system or the BIOS
for time and date. Operating systems other than the ones mentioned above may skip over the
BIOS to get date information directly from the RTC and CMOS memory.

For example, Novell Inc. OSes consult the RTC but use a windowing technique to set the
date across a network. NetWare 4.x and IntranetWare 4.11 assign to the 21st century all
two-digit year dates from 00 through 79; years from 80 through 99 go to the 20th century.

The RTC counts time like a digital watch. Every motherboard has a flat battery, similar
to a wristwatch battery, to power the RTC and CMOS. The RTC contains, among other time
information, six two-digit fields that depend on one another to tell the seconds, minutes,
hours, days, months and years.

Calling the clock real-time is a misnomer because it merely reflects the time setting
it has been given. A user can change the time just as he can move the hands on a wall

When the RTC’s year field rolls over to 00, the century entry may not update from
19 to 20 because CMOS memory does not depend on the RTC. But a 2000-ready BIOS—or
Windows NT—can make the one-time adjustment regardless of whether the system is
turned on.

Microsoft’s Cephas said NT maintains and writes directly to the CMOS, shielding
the hardware from application software. Versions 3.51 and 4.0 have other date-related
issues, but they deal consistently with the RTC and CMOS, Cephas said. If NT notices that
the RTC shows the year as less than 20 while the CMOS century data lists 19, then NT will
correct the CMOS entry directly.

NT also prevents the RTC and CMOS from being accessed by any application, Cephas said.
If an app tries to access the computer’s hardware, NT intervenes by creating
so-called virtual hardware to report correct century or other information.

Windows 9x handles dates a little differently, getting its information directly from
the BIOS. If the BIOS properly updates the CMOS entry when the clock rolls over, there is
no problem. But if the BIOS is not year 2000-ready and thinks the year is 1900, Windows 9x
compensates by showing 2000, Cephas said.

Most makers provide BIOS details on their Web sites, and several commercial utilities
are available to check BIOS readiness. The GCN Lab will evaluate some of the products
early next year.

If agencies do not plan to replace aging PCs with 486 or earlier chips, they should
search the makers’ Web sites for software drivers to roll over the date correctly at
the end of 1999.

Many older PCs’ BIOSes cannot update the complementary metal-oxide semiconductor
memory register by themselves.

Dell Computer Corp. year 2000 program manager Dave Cunningham said his company has
shipped 2000-ready BIOSes on all systems since Jan. 1, 1997, and many Dell systems built
in 1996 also are ready. Users of older systems can download updated flash BIOSes from
Dell’s Web site, he said.

Cunningham said a Dell BIOS checks the date on powering up, at any operating system
boot, and whenever an application or OS asks for the date and time.

For systems with 486 or older processors, he said, Dell has a small driver that
installs above the CMOS in main memory and keeps polling for time and date. When the
Y2000RTC driver finds that the real-time clock is within 15 minutes of 2000, it jumps into
action, counting the milliseconds until the changeover just after 11:59:59 p.m.

“Y2000RTC never allows 1900 to appear in the real-time clock,” Cunningham
said. The driver, which runs under all versions of Microsoft Windows, MS-DOS, Novell
NetWare and IBM OS/2, prevents any time gap that might otherwise supply an incorrect year
date to the BIOS, OS or applications.

Compaq Computer Corp. expects to post its workaround shortly, said Chuck Mills, year
2000 program manager. Mills said users do not need to download the free fix unless they


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