Year 2000 problem

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Year 2000 problem

Year 2000 problem, Y2K problem, or millennium bug, in computer science, a design flaw in the hardware or software of a computer that caused erroneous results when working with dates beyond Dec. 31, 1999. In the 1960s and 70s programmers who designed computer systems dropped the first two digits of a year when storing or processing dates to save what then was expensive and limited memory; such a system recorded the year 2000 as 00 and could not distinguish it from 1900. In sorting, comparison, and arithmetic operations, the year 2000 would be treated as if it were equivalent to 0 rather than 100, causing incorrect results. The algorithm used to calculate leap years was also in some cases invalid, creating an additional problem in calculating the correct date after Feb. 28, 2000. Because the designers of such computer systems expected them to be replaced before the beginning of the year 2000, using a two-digit date was not regarded as a problem. Thousands of older computer systems, called legacy systems, were still in use in the 1990s, however, particularly in the finance and insurance industries, creating a potential operational and financial nightmare, which was termed Doomsday 2000. In the late 1990s business, government, and other computer users spent thousands of hours and millions of dollars to correct the Year 2000 problem, and only minor problems were experienced after Jan. 1, 2000.
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Y2K problem

(Year 2000 problem) The inability of older hardware and software to recognize the date after the year 2000. The reason they could not was because the year was stored with only two digits in many databases; for example, 12-11-03 instead of 12-11-1903. Therefore, after the turn of the century, was this date 1903 or 2003? Every program that dealt with dates could have problems.

Dates Are Critical
Financial transactions often match dates in database records with today's date or with a future date. If the system does not handle dates correctly, bills do not get paid, notices do not get triggered and actions are not taken. After 2000, any system that could not recognize the change would cause erroneous output with applications that dealt with future dates. Although warnings of disaster prevailed, there were only a few incidents when all was said and done.

Fixing It Was a Massive Job
The solution to this "millennium bug" required upgrading hardware to support four-digit years, converting files and databases to four-digit years and converting all the software that referenced dates. Enterprises had a huge amount of legacy data files and thousands of programs that accessed them. With many older applications, the programmers who wrote them were long gone, and documentation was lacking. In many instances, the source code was missing. Even when changes could be made, the time it took to test them was taxing on the IT staff.

Just to Save Two Bytes!

The problem originated with punch cards that go back to the early 1900s. In order to cram an entire order or customer record into a single punch card with 80 or 90 character columns, the year was shortened to two digits. Why waste two columns for "19" when it was going to be "19" for a very long time. When punch card systems were converted to magnetic tape in the 1960s, and there was ample room to convert to four digits, laziness prevailed because 2000 still seemed very distant. Saving two columns (two bytes) in a punch card was appropriate, but not when there was ample storage on tape.

Problems Occurred Even Before 2000
For example, imagine a company wanting to delete customers who had not purchased anything in the previous five years. The program logic would add 5 to the year of the last order and compare the result with the current year. Suppose a customer last ordered in 1995 and the current year were 1996. Add 5 to 95 in a non-Y2K compliant system and the result was 00, not 2000. Since 96 was greater than 00, the customer record would be deleted. See data aging.

Another Date Problem 38 Years Later
Because of the way dates are stored in Unix systems, the year 2038 presents another challenge (see Year 2038 problem).

The Y2K Problem
When data were copied from punch cards to magnetic tape records starting in the 1960s, the two-digit year was generally copied verbatim because the next century seemed very distant. See 3 C's.

About Time
This conference was from the Software Productivity Group, an organization that provided the necessary training to deal with this sticky subject. (Image courtesy of Software Productivity Group)

Making a Strong Point
Year 2000 compliance software from Isogon was used to test IBM mainframe applications running the MVS operating system. (Image courtesy of Isogon Corporation.)

Perhaps Overly Dramatic
There was a lot of concern before the millennium that things could get out of hand. However, had the world not spent hundreds of billions of dollars revamping thousands of applications, there would have been many problems. There were only a few.

Even Before Y2K
Program maintenance is always a problem in this industry. This commentary from PROCASE Corporation was created more than a decade before Y2K. PROCASE provided software that could flow chart a program from its source code in order to make it understandable.
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References in periodicals archive ?
At the time, of course, people were still weary of thinking about the calendar because of anxieties over the much-hyped Y2K computer bug.
North is best known to Internet users for his prolific auguring that a Y2K computer bug would cause the calamitous end of civilization.
December 29 Former Beatle George Harrison is stabbed by Michael Anram, who apparently believed Harrison was the devil December 31 The Queen opens the Millennium Dome at Greenwich, London December 31 The Y2K computer bug fails to cause the predicted mayhem at midnight
Airline officials said the decline was partly due to passenger concerns about the Y2K computer bug.
But neither the Four Horsemen of the Apocalypse nor the much-vaunted Y2K computer bug even bothered to make an appearance.
The tourism decline this past January was about 7% world-wide, according to industry analysts, due to fears of the Y2K computer bug that turned out to be a complete non-event;
EPA chief Taichi Sakaiya has said he expects the GDP data for the October-December period to contract considerably from the previous quarter because of smaller winter bonuses and the negative impact of the Y2K computer bug.
The institute said it may have made mistakes during renewal work for a computer system controlling the Web site when it prepared safeguards against the Y2K computer bug late last year.
South Korea removed its Y2K computer bug alert Tuesday, saying the country's 13 major areas of concern such as banking and telecommunications have resumed normal operations without any computer problems.
Telephones in New Zealand, the first developed country to enter 2000, have become almost unusable but the trouble was not caused by the Y2K computer bug, officials of the Japanese Embassy in New Zealand said Saturday.
and the World Bank, is cooperating with 170 nations, and will offer support to help countries identify Y2K computer bug issues that may affect crucial sectors such as telecommunications, energy, financial and medical systems.
27 Kyodo Private-sector experts will be brought into the Cabinet Security Affairs Office and other government offices over the New Year period to help guard against possible cyber-terrorism involving the Y2K computer bug, government officials said Monday.