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The year 2000 problem is a potentially serious bug which will affect many computers over the next three years. The problem is caused by an assumption that two digit year codes (i.e. 1/1/01) refer to the twentieth century (1/1/1901) rather than to the twenty-first (1/1/2001). This may result in significant worldwide disruption when computer systems incorrectly operate on invalid dates. The Macintosh operating system and toolbox routines correctly identify dates up to the year 2040 and also correctly identify the year 2000 as a leap year. Some individual software packages may have problems if the programmers have used their own code to work with dates.
On the 1st of January 2000, many computers will take a trip back 100 years and think they are actually operating on the 1st of January 1900. This means they will also think that Saturday (1/1/2000) is Monday (1/1/1900) and many computers will also miss February 29th, 2000.
Depending on the types of work being done by the computer, this will either be inconvenient or completely disruptive. Many calculations done on computers depend on correctly determining the time elapsed between two dates and this bug will result in many incorrect calculations which could affect the world's financial markets, communications, and many other businesses. As well, many calculations made by computers are projections of future events. If these incorrectly use 19 instead of 20 for the century then the result will be wrong now. As an example, imagine a satellite navigation system which uses the date, time, and orbital information to work out where a staellite should be, and thus where the navigation system is located. It is very unlikely that a satellite will be in the same place in the year 2000 as would be predicted for the year 1900 and thus the system will fail. This becomes rather more serious if it fails on an airliner whilst it is carrying hundreds of people.
While it is unlikely that this will happen, the possiblity that this and other significant disasters will occur has resulted in an increasing concern in the computer industry and more recently government. While disruption of personal computers is inconvenient, disruption of businesses or essential services like air traffic control or hospital systems will cost money or lives. Legislation in place or soon to be enacted means that managers and company directors will be responsible for ensuring that their systems will pass through 1 January, 2000 without a blip. External consultants and insurance companies are already making huge profits from companies and government departments cleaning up their systems and as we get closer to the end of 1999 they will only get more expensive. The cost of fixing systems used by the US Government alone has been estimated at US$3.8 billion and this could easily be an underestimate.
How did this happen? When computers were first used widely in business and essential services they were extremely expensive and the memory used to run software was very precious. Programmers used any trick they could to reduce the size of programs and this included assuming that any two digit year referred to 19xx. This was done in the expectation that as it got closer to the year 2000 all of this old software would be replaced or discarded. Unfortunately many old software packages are still in use in many industries and the cost of replacing them has grown to the extent that in many cases it is cheaper to fix the old software.
The problem is however not limited to old software. Many newer software packages have had the same assumptions built into them. As well, the logic used in microcontrollers or PLC devices, which are widely used in many ordinary objects such as cars and lifts, may also be affected. Many personal computers are currently in use with BIOS chips that are not able to deal correctly with the year 2000. While these can generally be updated, the risk is that because of their ubiquity, many will be forgotten until they fail. Recently tests at the NASA Lewis facility found that 47 percent of the Intel-standard PCs tested failed to cope with dates after 1999.
An additional complication is caused by widespread confusion over whether or not the year 2000 is a leap year - it is. Years divisible by 100 are not leap years unless they are also divisible by 400. Thus, 1900 is not a leap year, but 2000 is.
When the original macintosh 128K computer was released in 1984 it was designed to correctly cope with dates up to 6:28:15 A.M. on February 6, 2040. More modern Macintosh computers running the current operating system have no trouble with dates between 30,081 B.C. and 29,940 A.D., which should be sufficient for calculating most people's mortgages and booking hotel reservations for some time to come. The Macintosh has always correctly identified the year 2000 as a leap year.
Additionally, the Macintosh uses a number of different calendar systems in different parts of the world such as the Arabic astronomical lunar calendar and the Arabic civil lunar calendar, Jewish calendar, and Iranian national calendar and these all correctly identify dates far into the future.
One slight complication is that the Date and Time control panel, for compatability reasons with System 6, will only allow entry of dates between January 1, 1920, and December 31, 2019. Apple assure us that they will update the control panel before then.
Under Rhapsody, dates up to 2039 are dealt with correctly, although two digit dates are assumed to be 19xx if not otherwise specified. The Yellow Box (Rhapsody running on other platforms other than the Macintosh) does not have a year 2000 problem, however the platforms it is running on may have their own problems which would need to be addressed. This is particularly an issue with IBM compatable PCs as many have problems in their hardware BIOS code with the year 2000.
Unfortunately, this does not imply that Macs are completely immune. Any program which is written on the Mac which works with dates and makes calculations based on years can have a problem if the person writing the code makes assumptions. This can include even simple "programs" like spreadsheet formulas. If you have had software written for you especially, its worth checking to make sure that it can operate with dates after 1999.
As well, despite Apples best efforts, some popular Macintosh applications will have some difficulty.
Claris claim that all of their current products are as safe as the operating system they are run on. Generally, their products prefer 4 digit years, but if two digit years are supplied, they always assume 19xx.
Filemaker Pro 3.0 and later specifically expand dates to 4 digits to make the year explicit, however older versions do not which can result in some confusion as entering 1/1/02 will always mean 1/1/1902. The expansion of years is done in as helpful a way as possible, in that if you enter 1/1/02 into Filemaker Pro 3 or later it expands it to 1/1/2002 during the last ten years of this century. Next century, for the first ten years, it will expand 1/1/96 to 1/1/1996. After 2010 it will assume two digit dates are 20xx.
ClarisWorks also uses a similar system and supports dates up to 9999 in spreadsheets. Claris Organiser works in a similar way and copes with dates between 1904 and 2040. Claris Impact will accept dates up to 2040. MacProject Pro accepts dates between January 1, 1973 and December 31, 2039. MacWrite Pro 1.5 gets its dates from the Date and Time control panel and thus copes with dates up to 2019 currently.
Excel copes with dates in the range from January 1, 1900 (1/1/1900) to December 31, 2078 (12/31/2078) at least, with more recent versions coping with a much wider range of dates. As with the Claris products, Excel generally expands two digit date entrys depending on the year in which the software is run although the exact details depend on the version (Excel version 2.x always assumes 19xx). However, this will only happen if cells are formatted as dates, If you have custom spreadsheets which work with dates formatted as numbers then it is very likely they will fail after 1999.
Word generally has no problems but the Word 6 find file command only use the last two digits of the year supplied and assumes that the first two are 19 which means that it will assume that requests to find documents created after 1/1/2001 are for documents created after 1/1/1901. Word 6 will also believe that files created on 1/1/1901 and 1/1/2001 were created on the same day.
Works versions 1 and 2 believe that any any year divisible by 4 is a leap year, which means that 1900 and 2100 are incorrectly identified, whilst 2000 is correctly identified for the wrong reason.
The following explanation of our calendar works was written by Brian Bechtel of Apple Developer Technical Support and is quoted from his article "The Year 2000: No Big Deal, or Apocalypse Never" http://devworld.apple.com/mkt/informed/appledirections/sep96/year2000.html
"The Gregorian calendar is a refinement of the Julian calendar, established in ancient Rome. The Julian calendar assumed a year of 365.25 days. The actual length of the solar year, however, is 365.2422 days, which produces an error of one day every 128 years. In 1582, Pope Gregory XIII adjusted the error that had accumulated over the centuries by canceling the ten days between October 5 and October 15. He further ordained that years divisible by 100 would not be leap years unless they were also divisible by 400. (From this rule, you can see that 1800 and 1900 are not leap years, but 2000 is.) This adjusted the Gregorian calendar to 365.2425 days and reduced its error to one day in 3,323 years. Many non-Catholic cultures adopted the Gregorian calendar over the succeeding centuries, calling Julian dates Old Style and Gregorian dates New Style. This change occurred in the United Kingdom and its colonies in 1752."
If you wish to confirm for yourself the compatability of your Macintosh with the year 2000, Apple Computer suggest the following three tests:
As an aside, earlier Apple computers vary in their support of dates beyond the year 1999:
 | http://www.year2000.com |
| http://www.aiia.com.au/Year2000information.html |
| http://www.uwinnipeg.ca/~leung/y2k.html |
| http://devworld.apple.com/dev/techsupport/insidemac/OSUtilities/OSUtilities-93.html |
| http://www.apple.com/macos/info/2000.html |
| http://product.info.apple.com/pr/letters/1997/961210.pr.ltrs.macos2000.html |
| http://devworld.apple.com/ngs/lpp/adrpub/docs/dev/technotes/tn/tn1049.html |
| http://www.claris.com/press/company/news/year2000.html |
| http://www.microsoft.com/cio/articles/related_y2k_links.htm |
| http://www.microsoft.com/cio/year.asp |
| http://support.microsoft.com/support/kb/articles/Q164/4/06.asp "How Microsoft Excel Works with Two-DigitYear Numbers" |
| http://support.microsoft.com/support/kb/articles/Q171/2/86.asp "WD6x: Find File Fails with Dates Beyond Year 2000" |
| http://support.microsoft.com/support/kb/articles/Q50/6/79.asp "Works Recognizes Incorrect Leap Year" |
| http://www.zdnet.com/macweek/mw_1136/nw_2000.html |
| http://es.rice.edu/ES/humsoc/Galileo/Things/gregorian_calendar.html |
| http://www.ast.cam.ac.uk/pubinfo/leaflets/leapyear/leapyear.html |
Internet mailing list for discussing year 2000 issues. To subscribe, send e-mail to listmanager@hookup.net with the text "SUBSCRIBE YEAR2000" in the body of the message.
Pope Gregory XIII
Inter Gravissimus, 1582.
Apple Computer, Inc.
Inside Macintosh: Operating System Utilities
Chapter 4, "Date, Time, and Measurement Utilities"
Apple Computer, Inc.
Guide to Macintosh Software Localization
Chapter 9, "Localized Macintosh System Software" and Chapter 11, "Calendars and Dates"
Coyne, G.V. , M.A. Hoskin, and O. Pedersen, eds.
Gregorian Reform of the Calendar: Proceedings of the Vatican Conference to Commemorate its 400th Anniversary. Vatican City: Pontifical Academy of Sciences, Specolo Vaticano
Erbshloe, Michael
Solving the Year 2000 Problem
Fairchild, Alea
Year 2000 Compliance : A Guide to Successful Implementation
Hayes, Ian and Ulrich, William
The Year 2000 Software Systems Crisis: Challenge of the Century
de Jager, Peter and Bergeon, Richard
Managing 00 : Surviving the Year 2000 Computing Crisis
Jennings, Kathryn
Year 2000; Best Practices for Y2K Millenium Computing
Kappelman, Leon
Year 2000 Problem: Strategies and Solutions from the Fortune 100
Murray, Jerome T
The Year 2000 Computing Crisis : A Millennium Date Conversion Plan
Miller, Stewart S
Year 2000 Solutions : A Manager's Guide to the Impending Collapse of Every IT System
United Kingdom. Parliament.
An Act for Regulating the Commencement of the Year; and for Correcting the Calendar Now in Use. 24 Geo. 2. c. 23, A.D. 1751. Anno vicesimo quarto GEORGII II. CAP. XXIII.
Yourdon, Edward and Yourdon, Jennifer
Time Bomb 2000; What the Year 2000 Computer Crisis Means to You!
This page created and maintained by Stephen Marshall
last modified 13th February, 1998