This has two related parts, both to do with the VAX-11 computer’s
operating systems
1. Investigate the structure of the VMS file system
here are two starting points, but follow things up, don’t just stop
here. Question 4 will require a further search.
https://en.wikipedia.org/wiki/Files-11
https://vmssoftware.com/docs/VSI_Gd_to_File_Apps_23Jul19.pdf
The answer these questions:
1. What is an “extent”?
2. Compare the FILES-11 file structure to multi- or variable-level
index structures from class. In what ways is it better or worse?
3. What is the index file, INDEXF.SYS? Is this structure a good or
bad idea, and why?
4. What are “ACL”s? Compare them with the normal Unix way of handling
file protections, -rwxrwxrwx etc. Have we anything to learn from
them? Could they be used with Unix file systems?
2. Investigate the VAX virtual memory implementation
here is a starting point for that:
https://pages.cs.wisc.edu/~remzi/OSTEP/vm-vax.pdf
The answer these questions:
5. They only use 512 byte pages. What problems does this cause? Are
there any benefits to such small pages?
6. Compare the VAX virtual memory implementation with the ones we
have studied (Intel’s and the emulator’s). In what ways is it
better or worse?
7. Why do you suppose operating systems are not like VMS any more,
and virtual memory is only very rarely done the VAX way?
Submit on blackboard as a regular assignment.