During the Y2K bug hype, I remember seeing a store announcing some kind of board that one would connect to the motherboard of a PC and the problem would be fixed. Were these devices legit and, if so, how did they work?

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    Well, I wouldn't put it right away like that. With as little information as the question provides, it could as well have been some clock card able to hold a 4 digit year. Without further information what computer(s) this was about, or what exactly the board was supposed to solve, an Answer is almost impossible. And yes, 2K was a great source of BS.
    – Raffzahn
    Commented Jan 1, 2022 at 4:09
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    @another-dave Of course it does not fix the problems you say, but it fixes another problem. If you have an old motherboard and manufacturer does not provide a BIOS update to work properly with the RTC chip after year 1999, the card provides an option ROM to fix that.
    – Justme
    Commented Jan 1, 2022 at 9:22
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    Mine worked by keeping me trapped in 1999. (Anything exciting happening in 2022?) Commented Jan 1, 2022 at 17:38
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    It took me a second to parse that "anti-Y2K-bug boards" meant a hardware device and not some kind of formal committee (as in a "board of directors") that would meet to discuss fixes for Y2K bugs. Commented Jan 2, 2022 at 10:34
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    @ZachLipton ‘Motherboard’ would be a great name for a parents’ council at a school… Commented Jan 2, 2022 at 16:17

1 Answer 1


From a CNN article I found about one such card:

Most pre-1997 PCs had real-time clock chips ticking off six-digit dates (mm-dd-yy) translated by the BIOS into eight-digit dates indicating the proper century. Most BIOSes aren't programmed to calculate the proper century after January 1, 2000, potentially causing system failure.

The Evergreen [Year 2000 Upgrade] card reprograms any PC's BIOS to make the proper translation. It also provides virus protection plus backup and restore functions for the programmable CMOS chip on which the BIOS resides. Because the card fixes hardware Y2K problems at the BIOS level only, the company recommends contacting software vendors separately for software fixes.

Based on this description, it appears those were simply ISA cards carrying an option ROM that patched the BIOS interrupt call that reads off the system date from the RTC (and added some unrelated extra functionality as well, because of course they did). As such, it seems those cards were actually functional, if pretty limited in scope, since they fixed only one aspect of the problem: they fixed programs that (directly or not) relied on the BIOS to obtain the current date. Installing such a card could not possibly fix programs storing two-digit years in internal data structures or on-disk file formats.

Here’s a photo of another such card, the Micro 2000 Centurion:

An 8-bit ISA card labelled ‘© 1997 Micro 2000, Inc.’, with a Dallas 12C887 RTC, a similar-size chip with a sticker labelled U3V2-4 (presumably the ROM), and two narrower chips labelled U1-FX-2 and U2-FX-2, also using stickers.

It’s not a complex device. On the right is an RTC chip. The other ‘big’ chip is likely a ROM, with what looks like a pinout compatible with TMM23256P. The two ‘narrow’ chips look like PLDs from the same series as ATF22LV10C (guessing by the part of the label that isn’t covered by the sticker), which I assume mediate between the ISA bus and the two ‘big’ chips. Any other such card I can find is similarly built: this Millennium BIOS Board, this Year 2000 BIOS Update Card from ‘Digital Research’ (probably unrelated to Gary Kildall), or this Zykon Millenniurm [sic] Pass YK2000 [sic] (this one may be an actual counterfeit, judging by the typos). Just an option ROM, a couple of chips to connect it to the 8-bit ISA bus and some jumpers or DIP switches to configure it, with something extra occasionally thrown in.

As the RBIL entry for the BIOS call notes, such a fix could equally well be applied with a TSR program, and some operating systems contained built-in mitigations that rendered the cards redundant; yet other OSes would bypass the BIOS entirely when maintaining their system clock, also making the cards unnecessary. However, those systems do not include MS-DOS (and by extension Windows 9x), which relies on BIOS services to read the RTC and includes no mitigations, so the cards were not entirely useless after all. Still, the critique in the CNN article (‘an overpriced, labor-intensive alternative to software fixes’) is quite fair.

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    That's odd that it would even be needed... My old PC XT clone up until the day it died a few years back (2015?) had no issue with Y2K with the standard on motherboard chip. Same chip everyone used back in the day... Commented Jan 1, 2022 at 16:48
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    @BrianKnoblauch It’s less about the RTC itself than about the code which handles it. There is not even a single standardised location in the RTC NVRAM where the century is supposed to be stored. It’s not hard to imagine some BIOSes might have just hardcoded the 19XX century. How prevalent that was is another matter… Commented Jan 1, 2022 at 17:13
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    @BrianKnoblauch And yet a component of Microsoft exchange server just stopped working for everyone at UTC 00:00 2022-01-01 because “2201010001 could not be converted to long” (paraphrased event log message). There’s a y2k22 bug in Microsoft Exchange. Commented Jan 2, 2022 at 3:10
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    Anecdata: I was at a bookstore on January 1st 2000, and they were unable to sell me a book because their PC-based cash register didn't work. I helped them set the BIOS date to 1994 (leaving them to deal with the leap year later) and it worked. Maybe this card would have helped.
    – mattdm
    Commented Jan 2, 2022 at 19:01
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    @OrangeDog, if you were lucky, the BIOS was a socketed chip. If you weren't, it was a soldered chip.
    – Mark
    Commented Jan 3, 2022 at 5:06

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