One of my customer is a world famous cultural institution. Around 2007 IIRC, they asked me if I could devise a way to backup their payroll system, because I was their go-to Unix/Linux expert and "it runs on some Unix thing".
So I went with the CIO to the HR office to check the "thing". The setup was as follows: between the two office windows, there was a small table with on it, a Sun SS20 workstation of 1993 vintage, connected to a bunch of 1 or 2 GB SCSI drives, all covered with a 5 cm, hairy blanket of dust. A tangled nest of serial cables (yep, the RS232 style) were going from a serial expansion MBUS card to all of the HR people's PCs in the room (through USB adapters). They were connecting to the thing using good old HyperTerminal...
The machine also had a modem that was used, eons ago, when it was under some form of support from the supplier of the solution, to monitor the setup. Of course nobody had done any update nor any system maintenance since 1998, so it was still running Solaris 2.x.
Of course I didn't have the root password. The thing was running a database (Informix or Oracle, not sure) that I planned to backup to a Linux server through NFS (keep it simple). So I basically had to write a shell script using a syntax compatible with this antique kit to run through cron... Fortunately they had a spare SS20 that I used for this purpose!
The pay of several hundred people (maybe a thousand) was relying upon this system... several million € of pay checks every month!