| Microsoft Year 2000 Readiness Disclosure
& Resource Center |
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| Windows Operating System Interactions
with BIOS and Real Time Clock |
| 9. Windows
98, Windows 95, Windows 3.x and MS-DOS Overview
Logic
built into the Microsoft Windows« 98 operating system will recognize
1900 as an error case and at boot up time will automatically set the
date forward to 2000.
Users of Windows« 95, Windows 3.x, and MS-DOS version 5.x or
later can address this rollover error by resetting the date in
Control Panel or by using the DATE command in MS-DOS.
The BIOS code that updates the RTC during run time may not
rollover from 1999 to 2000 right away, so to Year 2000 test
applications that directly access the RTC, it could look like a
rollover error. However, Microsoft is not aware of any non-test
programs that access the RTC and believes that most users will not
see rollover issues associated with the RTC not being updated at run
time.
How Windows 98 handles the error cases
In Case 1, the BIOS program does not update the century during
the POST routine. The Windows 98 operating system addresses this
error case by updating the century value from 1900 to 2000 at boot
time. Once the century register has been changed from "19" to "20"
the machine's BIOS and operating system should maintain the proper
date. However the 1900 trigger is not invoked beyond the year 2000,
so if the machine is left off for over a year, 1901 is stored in RTC
memory. In this case, you can reset the date in Control Panel or use
the DATE command in MS-DOS.
In Case 2, the BIOS software allows years only within a specified
range; for example, one type of BIOS does not accept the years 1980
û 1993 or 2000 û 2094. Windows 98 does not address Case 2. Microsoft
suggests that after 12/31/1999, you use a text editor such as
Notepad to add the date command to C:\Autoexec.bat.
Then each time the machine is turned on, you will be prompted to set
the correct date.
In Case 3, BIOS Setup does not recognize the year 2000 as a valid
date.
To update the century register, reset the date in Windows Control
Panel. The machine's BIOS and operating system should then maintain
the date properly.
How Windows 95, Windows 3.x and MS-DOS handle the error
cases
In Case 1, the machine's BIOS program does not automatically
update the century during the POST routine. When the system is
turned on, the date will read 1900. Windows 95 and Windows
3.x/MS-DOS will set the date to January 4, 1980, the first valid
date for the operating system. To update the century register, reset
the date in Control Panel or use the DATE command in MS-DOS.
The machine's BIOS and operating system should then maintain the
date properly.
In Case 2, the BIOS code that handles the year will allow only
years within a specified range. Unless you reset the date every time
the machine is turned on after 12/31/1999, the date on the system
will be invalid. For machines with this problem, Microsoft suggests
that after 12/31/1999, you use a text editor such as Notepad to
place the date command in C:\Autoexec.bat. Then each
time the machine is turned on, you will be prompted to set the
correct date.
In Case 3, BIOS Setup does not recognize the year 2000 as a valid
date. To update the century register, reset the date in Windows
Control Panel or use the DATE command in MS-DOS. The
machine's BIOS and operating system should then maintain the date
properly.
The following section provides detailed instructions for Year
2000 rollover tests in the Windows 9.x, Windows 3.x, and MS-DOS
version 5.x and later operating environments.
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