The Year 2000 Problem

Hardware Development Tools
Operating System Custom Programs
Overview "Off the Shelf"
Data Exchange




What Is the Problem?

The "Millennium Bug", or Year 2000 ("Y2K") Problem, arises because memory was so limited and expensive on early computers that programmers used every possible technique to save space. One such technique was representing years by only their last two digits, for example, 1967 would be stored as just "67". (This wasn't as silly as it sounds now when you consider that, in the late sixties, 16Mb of memory cost about $15,000,000 and the maximum expected life of any program was about ten years.)

However, if such programs are still in use in the year 2000, they may take the year "00" to be 1900, 0 or something else.

Very many data processing operations rely on dates and date comparisons. For example, a loan taken out in 1995 and paid out in 2005, should attract interest for ten years; but a program with the Millennium Bug might calculate the term as 90 years or minus 90 years. Such problems could effect creditors, debtors, financial forecasting, tax calculation, inventory control, process control and many other aspects of any business.

The Millennium Bug effects your entire business. You need to take action as soon as possible.

The Millennium Bug not only effects what we normally think of as business computer applications. It can occur in any situation involving a computer or microprocessor. These include manufacturing control systems, telecommunications, money transfer and other financial systems, gas, water, and electrical utilities, stock markets, transportation, national defence, office equipment, home computers, security systems and appliances. Not only may your computers reset themselves to 1900 or 1980, a photocopier that records the number of copies made in a day may fail because it does not recognise that "00" is a valid year, a preprogrammed fax machine may fail to send out notices, a voice mail system may wipe messages that it thinks are a hundred years old, a preprogrammed money transfer may fail to take place or an electronic security system may not function properly.

There is a second problem which arises in the year 2000 because (unlike the year 1900), the year 2000 is a leap year. This problem comes about because many programmers, like many other people, have been uncertain of the rules for leap years. The result is that some programs may not accept that "29 February 2000" is a valid date.



The Millennium Bug in PCs

Problems with the Millennium Bug may arise at several levels in a PC system:

operating system
"off the shelf" application
development tools
custom applications
data exchange.

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Very Old PCs
Prior to the IBM AT (late 1984), personal computers did not have real time clocks. So, there is no Millennium Bug issue with very old PCs.


IBM-compatible PCs to 1996
From the introduction of the (80286) AT, IBM-compatible PCs have a battery-backed real time clock which is used to keep track of the time and date. Until 1996, almost all of these clocks stored the year as two digits. This means that most AT-class PCs built before 1996 will not correctly roll over from 1999 to 2000.

For many purposes, the solution is simply to reset the date. In DOS, type DATE 01/01/2000 at the DOS prompt. In Windows, access the Date icon in the Control Panel. (N.B. This will correct the system date but does not mean that programs will work correctly.) However, if you choose to do this, be careful that the new date is retained if the computer is switched off and back on. DOS only reads the real time clock when the computer is booted. It then calculates the time and date from the number of elapsed processor cycles.


IBM-compatible PCs from 1996
From 1996, many manufacturers introduced models which store the year as four digits and, so, do not suffer from the Millennium Bug at this level. However, there is no universal rule. Major brand vendors are able to tell you which models are compliant.
If you have clone PCs, you will have to test each computer individually, even if it was purchased recently. With clones, even two computers which appear to be the same model, made at the same time, may behave differently.

IBM has stated that all of its PCs and servers built after 1 January 1996 will roll over correctly. Full details are on IBM's web site at

Compaq warrants all PCs and servers sold after 7 October 1997 as being year 2000 compliant. A ROM upgrade may be available for older systems. For details see Compaq'a web site at

Digital states that all current models (1998) are "year 2000 ready" for further details see

HP has stated that all Vectra models from late 1995 will roll over correctly. Full details are on HP's web site at

Toshiba states that all models produced after 6 April 1996 are hardware compliant. See for details.

Impact Systems has stated that all of its computers use the Award BIOS and that all Award BIOS systems dated from 7 July 1995 correctly handle dates up to 2079. See


Apple Computers
Apple 11 computers, other than the 11gs, did not have a real time clock and, so, are not susceptible to the Millennium Bug.

Macintosh computers prior to the G3 (and the Apple 11gs) work on a system of assigning numbers to dates beginning on 1 January 1904 and ending on 2 June 2040. All Macs correctly recognise the year 2000 as a leap year.

The G3 Macintosh uses a 64-bit date whch handles dates from 30,081 BC to 29,940 AD.

So, Mac users do not appear to have a problem at the hardware level (yet). NB: This does not mean that Mac users are exempt from the Millennium Bug at other levels.

For further information see:



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Operating Systems

As noted above, the hardware (BIOS) of older PCs stores the year as two digits. This means that the year 2000 is stored as "00".

All of Microsoft's newer operating systems, Windows NT 3.51(sp5), Windows NT 4.0, Windows 98 and Windows NT 5.0 have logic built into them that will recognise "00" as an error case and will automatically compensate by setting the date to 2000. All of Microsoft's older operating systems since MS DOS 3.0 interpret "00" as 1980. (MS DOS 1 and 2 did not read the real time clock.)

Microsoft states that "Microsoft operating systems all store and manipulate dates in four-digit formats. Additionally, the system clocks have been designed to recognise the year 2000 as a leap year. The File Allocation Table (FAT) 16bit and 32bit versions used by MS-DOS, Windows, Windows 95 and Windows NT recognises dates up to 2108. The File Allocation Table for the Windows CE operating system recognises dates up to 2999. The Windows NT File System (NTFS) recognises dates to 29,601"

Microsoft, however, distinguishes between its operating system and the programs which are shipped with the operating system and which most people think of as part of it. For example, the Windows File Manager (winfile.exe) shipped with Windows 3.1 and Windows 95 does not display dates after 1999 and must be replaced by an updated version. So, Microsoft operating systems will have to be "patched" or replaced with Windows 98 or NT 5 before the year 2000.

For further information see


Novell states that Netware 3.11 and prior products are not being tested for year 2000 compliance and should be upgraded to Netware 3.12 or later.

Netware 3.12 requires patching. Netware 3.2 is "Year 2000 Ready" but a patch is recommended..

Netware 4.10 and prior 4.x versions should be upgraded to version 4.11 which is "Year 2000 Ready"

For further information, see


Apple Macintosh operating systems are year 200 compliant although the Date Control Panel only works between 1920 and 2019.

For the Apple 11gs, operating systems from System 6.0 and Apple ProDOS from release 8 V 2.0 are compliant.

For further information see:


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"Off the Shelf" Applications

This includes products such as word processors and drawing programs which are not date dependent but also accounting programs which may be highly date dependent. (Those products which are used to create applications, such as spreadsheets and database programs, as discussed separately..)

Generally, software manufacturers state that their current (1998) products are year 2000 compliant but older products cannot be guaranteed to comply. They recommend that users concerned about compliance upgrade to the current version.

We recommend that you check with the vendors of all applications programs which you use to identify any Year 2000 issues. Some relevant web sites are:

Microsoft products which are NOT compliant include Word for MS DOS and Access 2. Products which have what Microsoft calls "minor issues" include Internet Explorer v. 3 & 4, Word 95 (v. 7), PowerPoint v. 4, Visual FoxPro v. 2 & 3 and all versions of Visual Basic


Inprise (formerly Borland):

Corel (incorporating Word Perfect):

Intuit (Quicken): pport/year2000.html

Datatech (MYOB):


FileMaker Inc (formerly Claris):




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Development Tools

Programs which are used to create custom applications may have year 2000 problems at two levels. The development tool may have inherent problems and the programs, macros and so on created using the tools nay have problems. In this section, we will deal with problems which may be inherent in the development tools themselves.


All spreadsheet programs that we know of can handle dates beyond 2000 correctly but the way in which they do it varies.

All common spreadsheets can be set up to display years as four digits. This is the safest course of action. Microsoft recommends that Windows 95 users change the "short date format" in the Control Panel - Regional Settings to /9999. MS Excel, and most other spreadsheets, will then display four digit years.

If you decide to display the year as two digits, most spreadsheets use a "date window" to interpret your input. For example, Lotus 1-2-3 97 uses a default date window of 1950 to 2049. This means that a year below 50 is assumed to be in the 2000s but a year above 50 is assumed to be in the 1900s. Different programs, even different versions of the same program, behave differently. You should check your documentation to be sure that you understand what will happen.


The two most commonly used database programs are MS Access and the dBase family.

All MS Access products store years as four digits. However, MS Access 2 is not year 2000 compliant. All two-digit years are assumed to be 1900s.

MS Access 95 and later use the "date windowing" system common in spreadsheet programs. Different versions use different date windows. You should check your documentation to be sure that you understand what will happen.

Microsoft recommends that Windows 95 users change the "short date format" in the Control Panel - Regional Settings to /9999 to make all years four digits.

All dBase family products (since 1983) store dates as YYYYMMDD, although only two year digits may be displayed. dBase, Clipper and FoxPro users are recommended to make the four year digits visible using SET CENTURY ON. (Note: with CENTURY OFF, Foxpro does not accept 29th February 2000 as a valid date.)


For further information see:



Inprise (formerly Borland):




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Custom Applications

Custom applications are any programs, macros or even spreadsheets which you have developed "in house" or which have been developed specifically for you. Obviously, it is your responsibility to check that these applications are year 2000 compliant.

To do this, you may need to engage outside help. We suggest that you act soon because our experience with our own custom programs suggests that the task is likely to be much larger than you expected. And also because the skilled programmers you may need for your project are going to be harder and harder to obtain as the year 2000 approaches.


Some resources which you may find helpful in reviewing your custom applications are at:

The Year 2000 Information Centre:

The Australian Governments' Year 2000 Home Page:







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Data Exchange and Storage

Data Exchange
If you transfer data from one application to another, it is possible for date information to be lost. For example, if you have a spreadsheet with four digit dates and save the data as CSV text, the century digits will be lost.
The safest format for data exchange is dBase file format.

Data transfers to and from non-PC systems may also cause date information to be lost. This will need to be professionally checked.


Data Storage
As a result of concerns about the year 2000 problem, many businesses will be changing their equipment and programs. Tis itself creates another potential problem -
you need to carefully ensure that all of your archived and backup data is compatible with any new software which is introduced.

A further concern related to data storage is the software used with backup tape drives and the like. In many cases, this software will not back up data which seems to be older than data already archived. Some of this software uses a two-digit year and will take data from the year 2000 ("00") as being older than data from 1999 ("99").



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Revised 15 May1998

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