23 hrs
volsano
One Y2K remediation I worked on had systems from the 1960s -- crucial systems that ran the whole show.

We easily (for some definitions of the word) fixed their 1980s and 1990s stuff that used 2-digit years.

But we did not touch the 1960s and 1970s stuff that had a specialised date storage format. It was 16-bit dates. 7 bits for year. 9 bits for day of year.

It was too assemblery, too unstructured, too ancient.

And, anyway, 9-bit year counting from 1900 (as they did) was good until the unimaginably far future.

The unimaginably far future is nearly with us: 1900 + 127 = 2027.

I am waiting for the phone to ring so I can apologise, - and quote them an unimaginably large number to finish the job.