Gregory's Server
I'm surprised you had a 486 PC without a battery-backed hardware real-time clock. I was under the impression they all did. Mine did. It knew quite well what time it is when powered on (unless the battery died).
Indeed, a lot of 486 motherboards today are inoperable because the battery leaked and its corrosive electrolyte has damaged the board.
The original IBM PC didn't have a battery-backed RTC, though. That one did require you to type in the current time at power on.
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@leeloo
Anyway, some RTCs had a century register and some didn't. https://wiki.osdev.org/CMOS#Century_Register
Some RTCs with a century register suffered from a bug where it wouldn't actually be incremented. https://www.dell.com/community/en/conversations/windows-general/y2k-timedate/647e65b4f4ccf8a8dec10c7b?commentId=647e666bf4ccf8a8decf8ca7 🤦♂️
Not sure about my 486. It was powered on and running Linux when the century rolled over. If the RTC did have an incrementation bug, it would've been corrected automatically; resetting the RTC was part of the shutdown sequence.
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@fatsam
@leeloo
Anyway, some RTCs had a century register and some didn't. https://wiki.osdev.org/CMOS#Century_Register
Some RTCs with a century register suffered from a bug where it wouldn't actually be incremented. https://www.dell.com/community/en/conversations/windows-general/y2k-timedate/647e65b4f4ccf8a8dec10c7b?commentId=647e666bf4ccf8a8decf8ca7 🤦♂️