[loph]

Some businesses are still using DEC PDP-11s, first released in the 1970s. Those are even more "ancient." Many of these are used for industrial controls, among other applications.

see: https://news.ycombinator.com/item?id=30505421

The article does not mention what OS is being used, but RT-11 was designed for "real-time" applications. That was released in 1973, so over 50 years ago.

[estimator7292]

IBM is still producing mainframe systems to this day. More modern for sure, but still fundamentally an ancient system and architecture

[tim333]

Gosh - I'm surprised those still run. That the first computer I used back in 1978 or so. I see there's an emulator, SIMH, that will let you run PDP-11 stuff on Linux.