Need to save memory space root of problem
Today, we only need around $500 to get 32 megabytes RAM for a computer. However, in the 1960s, the price of 32 gigabytes RAM (one per cent of 32 megabytes) was almost US$1 million (HK$7.8 million).
This was why programmers tried to save as much memory space as possible. If you were born in 1966, this could be represented as 66 by using only the last two digits to record the year.
To calculate your age in 1999, the computer simply subtracted 66 from 99 to give the age of 33.
After midnight on January 1, the date 2000 would have been interpreted as 1900 by the computer, if you had not rectified the problem. Also, the computer system might have stopped working, shut down or refuse to accept instructions.
It would calculate your age as -66. As no one has a negative age, you might not have been eligible to be paid a salary, receive social benefits or interest from your bank.