PennOS — UNIX-like Operating System

Background: PennOS is a modular, UNIX-like operating system built from scratch in C for a graduate operating systems course at the University of Pennsylvania. It combines a preemptive priority scheduler, full process lifecycle management, and a FAT-based file system, with an emphasis on how scheduling decisions shape system performance and fairness.

My Contributions:

• Built a custom OS kernel integrated with preemptive priority-aware process scheduling, foreground and background processes throughout the process lifecycle: process creation, execution, backgrounding, foregrounding, and termination, complete with user-level concurrency using the spthread library.
• Designed and implemented a modular FAT-based file system enabling persistent data storage and streamlined I/O handling.
• Integrated between kernel and scheduler, supported multi-process file operations and directory management.