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Note to Consultants and Resellers TD and Y2K TD Technical Paper

Time Dilation

The thorny issue also known as the Crouch Echlin Effect.

by

Jace Crouch

General information about the current state of TD research is available at:

http://www.nethawk.com/~jcrouch/#TDTools-info

TD, Time Dilation, the Crouch-Echlin Effect or CE/TD is an elusive but serious aspect of the larger Year 2000 issue that was discovered by Jace Crouch and Mike Echlin and first reported on the newsgroup comp.software.year-2000. Specifically, TD refers to the time and date instabilities that will occur in the year 2000 and beyond on some personal computers and some embedded systems.

These time and date instabilities occur when BIOS time and date routines improperly access a non-buffered RTC during startup, resulting in a personal computer or an embedded system that has difficulty calculating or retaining the correct time and/or date in the year 2000 and beyond.

On these systems the time and/or date will intermittently and abruptly "leap" forward (or occasionally backward) when the system is powered up, not only causing the system to display and store an incorrect time and date, but also leading in certain instances to the failure of com

ports and hard drives, cmos scrambling, the OS ceasing to function properly because it is suddenly operating at a date beyond its original design parameters, and occasionally resulting in a system that will not boot up, or even make it out of POST.

These time and date instabilities can occur after the year 1999 because the BIOS then takes longer to access and process data obtained from the RTC, and on systems with a non-buffered RTC the BIOS may do this while the data is incorrect.

In the era 20xx, a non-buffered RTC accessed shortly before the update flag is set may return bad data because the time and date calculations take longer than 244 microseconds in the era 20xx and the calculations may extend into the period when the RTC is in update status.

If this occurs when the RTC is accessed during POST, Time and Date instabilities can occur not because this incorrect data used to calculate time and date for the software clock, but also because the incorrect time and date may get written back to the RTC/CMOS, thereby sustaining the time and date errors until the RTC/CMOS is reset by the user or by remediative software.

Occasionally (but devastatingly), the events that result in TD also result in CMOS corruption and/or hard drive boot sector corruption. For a detailed description of how this works, see

Mike Echlin's long promised software suite, TD Tools, is available. A detailed description of TD Tools is available at <http://www.nethawk.com/~jcrouch/#TDTools-info>. Simply put, the

presence of a non-buffered RTC and susceptibility to TD can be detected and evaluated using Mike Echlin's tdtest.exe and tdfind.exe. The time and date instabilities associated with this phenomenon can be corrected with Mike Echlin's tdfix.exe.