Good times. /s

I had to recover a hard drive for a 'server' (read:ancient desktop with a hard drives long out of production and pre-ebay) running DOS 3.3, that <ta da> ran all the magnetic locks for several buildings. All of a sudden, depending on how the door was setup locally, the doors defaulted open or locked (there were some exceptions, newer models for instance). For a financial institution, in the Windows XP era. Software vendor went bankrupt, 10 years earlier.

It was a textbook SNAFU. But someway, somehow, we cobbled together a working DOS 5.0 system with the oldest of the stock we could rob from someplace including checking with some used pc stores in the area, and got it back to working in about 6 hours.

It turned out to be a big win for our team in the end, but I was literally digging through old manuals to remind myself of long forgotten knowledge from an operating system of my early childhood.