[nijave]

Lots of embedded systems like routers run read only although maybe they're not technically ROM. Usually they mount the root filesystems read only and create some small ram disk/tempfs for logs. Persistent settings go to a small NVRAM area

The root filesystem is only written to when you flash a new OS image

[seba_dos1]

The context of ROM here is "can execute code without putting it in RAM" rather than "code is stored in a read-only memory".