Operating Systems

Basic idea

The software layer between hardware and applications. Manages CPU scheduling, memory, I/O, files, and security; provides processes/threads, an address-space abstraction, and system calls.

Key facts

• Core abstractions: processes, threads, virtual memory, files, sockets.
• Scheduling: preemptive (round-robin, CFS), priority, real-time.
• Memory hierarchy: registers → L1/L2/L3 cache → RAM → disk; each $\sim 10\times$ slower than previous.
• Modes: user / kernel; syscalls cross the boundary.

Resources

• http://littleosbook.github.io/

Siblings

• ai
• compression
• computer algebra
• data structures
• distributed systems
• formal verification
• programming language theory
• search
• theoretical