I knew of a Windows 95 host running virtualized in a corp environment until at least 2014 or so. It was surprisingly sturdy, I only had to remote into it once or twice when the old software it was running hung up on something. It was old medical software and we apparently had a couple clients still interfaced to it.

Win95 is only 30 years old and runs natively on some modern hardware.

Apparently there is important stuff still running in emulated PDP-11s, almost double the age.

It needs quite a few fixes to even run in a VM. But it can be done: https://github.com/JHRobotics/patcher9x

This post doesn't go to to great detail, but seems to run natively:

https://www.reddit.com/r/windows/comments/1n1no1k/august_202...

It might be possible to use the rest of that RAM above the 4GB barrier as a ridiculously fast RAM disk, with an XMS driver like this one:

https://github.com/Baron-von-Riedesel/HimemSX

Huh, so someone actually built this? I was thinking about something similar the other day, in the form of a Windows 9x driver that would use that inaccessible RAM as a "page file".

I did a similar thing on my DOS PC. Lots of DOS software gets confused when there is more than 64MB of XMS/EMS free. So I just gave 64MB of the 128MB to smartdrv. It's more RAM drive I ever had when using DOS for work back in the day.

Win95 complains about needing REAL mode compatibility for a RAM disk though. I wonder how much performance degradation is noticeable with a RAM disk though.

Yes certain software for Canadian made nuclear power plants, comes to mind. Was a post on the VCF forums about a job listing that required PDP-11 knowledge.

The screenshots show the program was made for DOS. Very likely Windows was used just for network file sharing.

Ya, RPG assumed character based IO so probably a safe bet that they just ported stuff that ran on IBM character based terminals and just made it run in DOS. (I worked in RPG in the 80's)

There are subtantial amounts of large industrial processes still in operation using equipment from the late 19th century.

Do you mean 20th? Even current looms, steam engines, stills aren't from the 18 hundreds

No, I do mean the late 1800s. Operations processing "low level" materials like agricultural, steel, and mining.

There are an awful lot of pieces of hardware around still using atoms from when the Big Bang detonated.