The company I work at does industrial process engineering, and a few of our customers have plants for which we do automation (PLC programming, visualization, ..

The company I work at does industrial process engineering, and a few of our customers have plants for which we do automation (PLC programming, visualization, ...) that are fairly ancient (1980s - mid-1990s) and. Some of these PLCs were made by a company that since has gone out of business, and the software for programming them runs on DOS. MS-DOS, in fact. We tried setting it up on FreeDOS, but apparently only the real thing will do. One and a half years ago, I had the pleasure to install MS-DOS 6.22 on two programming computers. Finding 3.5" floppy disks was ... interesting. But it was fun to see how a freshly installed DOS will boot within seconds, even on fairly dated hardware. Fun times! ;-) (Some of the visualization workstations at one of those plants seem to run DOS VMs on top of QNX so a single computer can run several displays, but I don't know about the details...)