For example, the year 1968 was recorded as 68. The two digit savings may not seem significant today, but it was then. This practice was continued well into the 1990's by many software companies. The year 2000 problem is that computer software using only two digits will record the year 2000 as the year 00, which may cause problems with date dependent calculations. To make matters worse, this practice was imbedded in hardware via BIOS software and computer chips that will not recognize the new century.
Computers do what they are programmed to do.
If the programming is not well thought out, the results may be in error. As a part of testing for year 2000 compliance, many companies are simulating turn of the century transactions and calculations. The problem isn't so much with computers that shut down entirely because those should be caught before the year 2000 arrives. The main problem is with computers that work and give answers that are believable, but inaccurate. These are the problems that will be difficult to detect.