Not sure why you're posting an OMSI Pascal question here at OpenACS but you've lucked out ...
I'm one of the two principal authors of the old PDP-11 OMSI Pascal compiler you're referring to. I did the work under contract to ESI while in college. No development work has been done on that compiler since the late 1970s.
The compiler uses the standard RT/11 device drivers and the standard API to load and reference them. You should ask Mentec if they've modified the application-OS API. If not, drivers shouldn't be a problem.
A more likely source of the dump to ODT is memory management. Clearly this has changed since 4 MB is being made visible to the operating system and applications. The PDP-11 is a 16-bit computer and the original architecture only allowed direct reference to 64KB total, 32KB in I[nstruction] space and 32KB in D[ata] space. Obviously changes were made to make 512KB available and even more changes to make 4MB available.
