OS/161
OS/161 is a teaching operating system developed at Harvard University. It is intended to "feel like" the BSD operating system, but with most advanced components removed.
I worked alongside another student to implement numerous features into the operating system as a series of assignments for UNSW's COMP3891 "Extended Operating Systems" course.
Features implemented
File handling
We implemented a file table, and used it to implement system calls for
openreadwriteclosedup2
Virtual memory subsystem
We created an externally-chained hashed page table to support virtual memory, including support for copy-on-write. It dynamically allocates frames whenever a page fault occurs.