EOPs for access/entry terminals found mostly in office buildings. To be specific, they're the ones that you'd enter a passcode into, tap a keycard or ID against, or something similar. Due to the relative “technical obscurity” of these devices, it is difficult to say what they'll usually run. It can be assumed that many of them will be based off of MIPS or ARM architectures, running some sort of Unix, Windows CE, or custom operating system.

download a mips toolchain

Hard to determine the “Operating System” status of this device, but it does run DOOM, given you cross compile for MIPS. If this does run Linux or something, it’s not stated.

https://www.youtube.com/watch?v=OdEGUXaBN24

https://old.reddit.com/r/itrunsdoom/comments/jdvvtm/doom_on_my_access_terminal/