PennOS

PennOS is a UNIX-like operating system that runs as a single process on a host machine, using threads to simulate independent processes scheduled by a custom kernel. The kernel tracks each process through a PCB — PID, parent/child relationships, file descriptors, priority, and state — and handles signals with an init-based model for reaping zombies. Scheduling is priority-based round-robin across three weighted queues, firing on a 100ms clock tick. Storage is handled by a custom FAT file system with its own system calls. On top of all of that, we built a fully interactive shell with job control, I/O redirection, and scripting support.