1. What is the year 2000
problem?
The year 2000 problem, commonly known as
Y2K, is a computing issue related to the way computers handle and
store date information. A date-related computing issue in any one of
three areas of your PC system (hardware, software and
personal data files)
can potentially cause problems.
The year 2000 issue stems
from three principal causes. Personal computers, even if new, are
not immune to these risks. Because the year 2000 issue has multiple
causes and is varied in its impact, there is no one-size-fits-all
solution to address it.
The three major contributing causes
to the year 2000 issue are:
The use of two digits to represent a four-digit calendar
year.
This is the most common source of year 2000
problems. Errors may occur because of the way that software or
hardware handles dates that are represented by only the last two
digits of the year, excluding specific information about the
century. Interpretation of two-digit
years always requires an assumption or
interpretation about the intended century.
As we enter the
next century, a computer system that incorrectly interprets the new
century as 1900, instead of 2000, will be at risk; calculations
based on dates in the "new" century will be calculated from the year
1900 instead of the year 2000. For example: 2000 - 1998 = 2 but 1900
- 1998 = -98 (or 98 if the software program does not permit negative
numbers).
The
year 2000 is a special-case leap year.
Because a
special-case leap year occurs once only every 400 years, some
software may not recognize the year 2000 as a leap year. (Years
ending in 00 are not leap yearsùunless they are divisible by 400.)
If the formula for determining a leap year does not include
special-case occurrences, dates following February 28, 2000 will be
offset by one day.
Programmers' use of dates for special
meanings.
Older software programs, particularly custom software
programs, may contain dates that have special
program-related meanings. The most well-known example is the date
9/9/99, which may have been used by a programmer to indicate such
meanings as "save this data item forever," "remove this data item
automatically after 30 days," or "sort this data item to the top of
the report." Different "special dates" may have been assigned
different "special meanings," depending on the programmer and the
program. This is why it is so difficult to track down potential
problems within older or custom programs.
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