Here you can find the Oric Atmos ROM 1.1b Disassembly converted to easy-browsable format.
https://iss.sandacite.com/tools/oric-atmos-rom.html
You can click on any instruction argument which is in the range $C000...$FFFF to jump to that address

The provided page is simple static html - you can save it for offline usage.
Happy hacking!
iss