The real-time clocks used in today's personal computers do not track centuries only years

The year 2000 poses one of the most significant challenges ever faced by the information technology industry and will have an enormous impact on business applications, package solutions, systems software and any other piece of equipment or instrumentation controlled by a computer chip. Wall Street analysts and others are predicting as many as 20 percent of businesses and governments will shut down because their systems were not adapted in time.

What exactly is this crisis? Put simply, it is the absence of the two-digit century value within the date that distinguishes dates as either 19xx or 20xx. The problem was created because of the limitations of earlier technology and the historically higher cost of storing information. Traditionally, the strategy was to save space and store as few digits as possible. This meant we saved 2 bytes per date by not storing the century value resulting in significant savings at the time.

If you brushed off the year 2000 as a mainframe problem, consider this: Microsoft says 32-bit Windows (Win95 and NT) will correctly process the years 1980 to 2099. However, most PC's with 16-bit Windows (Win 3.1) will have a problem. On January 1, 2000, an estimated four out of five of the PC's using 16-bit Windows will reboot to the year 1980 or 1984. This particular problem is fairly easily resolved (by resetting the date on your machine), but there are other problems lurking within the PC environment.

Shrink-wrapped software (that software which you purchase off-the-shelf at your local discount store) may cause you problems. This is true even if the manufacturer is one which is considered a highly reputable company. For example, most Windows applications have date limitations hard-wired into them. In some cases, the date limit is the year 9999 and we consider this to be an acceptable limitation. In others, such as Microsoft Access 95, the limit is 1999, after which you must always enter a 4-character year. Excel versions 4, 5, and 7, crumple after 2019.

The Y2K Leap Year Bug

Another date-related problem will occur on February 28, 2000. The initial release of Lotus 1-2-3 did not account for the turn-of-the-millennium leap year. The program does not know there is a February 29 in the year 2000. To make matters worse, competing spreadsheets Excel and Quattro Pro, duplicated the problem, presumably for compatibility.

Embedded Chips

In addition to the potential year 2000 problems with PC's and computer mainframes, a problem exists with "embedded" chips controlling everything from power plants to washing machines to building elevators. Embedded systems are written in low-level code and then burned into a chip's read-only memory. Except for some of the newer programmable memory chips, most chips cannot be altered. If the chip accepts time and date input, it may behave unexpectedly or even completely fail. These chips are found in products and/or systems that do not readily fit in the universally defined area of information technology, but in many cases, have more potential negative impact if they are not year 2000 compliant.

By definition, systems, equipment and instrumentation with embedded chips will require persons with expertise in the product (the vendor or manufacturer) to test for and fix year 2000 problems. Each embedded system must be treated as if it were a different program. Without an "expert" to help, your system is at risk.

Some additional Y2K resources found at the Team 2000 web site:

Every personal computer contains two clocks: a built-in hardware clock and a virtual clock. The hardware clock (real-time clock) runs whether the system is on or off. The virtual clock (system clock) is set to the real-time clock when the computer is turned on and exists only while the computer is operating. While the computer is up and running, the two clocks run independent of each other.

The system clock is a 24-hour timer and has no real concept of days, whereas the real-time clock tracks the time and date. In fact, the system clock has no concept of traditional hours, minutes, and seconds. It merely increments a counter 18.2 times per second. The operating system, which is dependent upon the system clock for the time, converts the counter into hours, minutes and seconds. As for the date, the operating system reads the real-time clock via the basic input/output system (BIOS) during initialization, then tracks the date independently based on the system clock rolling over at midnight.

The real-time clocks used in today's personal computers do not track centuries only years, e.g. "96." After December 31, 1999, the real-time clock merely indicates year "00." It is the responsibility of the BIOS to track the century and preserve that information in the real-time clock's memory. The BIOS assumes that the years 1900 through 1979 cannot occur, so when the year is within 00 - 79 and the century information is 19, the BIOS sets the century information to 20. If the BIOS does not track the century correctly, the operating system will be given an invalid year and most likely will assume 1980. (Microsoft operating systems do not support dates earlier than 1980.)

Caveats

Since the two clocks run independently, the real-time clock can be set to any nonsensical value and the operating system will not notice. Such will occur January 1, 2000 if your system does not support the year 2000. As long as the system is running, the operating system will correctly support the occurrence of the year 2000. Problems will occur, however, when the system is rebooted or powered off, then powered back on. This is the first caveat: setting the date and time just prior to the year 2000 and just letting the new year occur is not a valid test. The real-time clock may be invalid, but the date according to the operating system will be correct. The system must be powered off, then powered back on to complete this type of test.

The second caveat applies when the operating system is used to set the date and time. The system clock will always be set by the operating system. However, not all operating systems will concurrently set the real-time clock with the system clock. In this scenario, the above methodology may cause a system that correctly supports the year 2000 to fail if the operating system does not set the real-time clock as well.

Y2K Campus Web Sites