I know there are places that still offer support for MPE/ix so I am sure people are relying on it. HP EOL'd in 2006 and stopped all support in 2010. System was around for about 40 years and I spent about 4 years in the mid-90's working on a few of them at a manufacturing company. I was working on a pair of HP-3000 that were bought in the last 70's. I got invited to the last powering off in 2002.

Nice unique little systems. If I remember right, by the mid 80's the CPU was emulated on a PA-RISC chip. Also, at some point the HP-3000 ran MPE XL and the HP-9000 ran HP/UX using the same hardware. SPL (system programming language .. cr native name there) was .. interesting. I still have some of the OS manuals lying around attic.