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Fundamental OS Concepts

Source: UC Berkeley CS162, Fall 2020/2021 - Prof. John Kubiatowicz, Lectures 2-5

Before you can reason about locks and race conditions, you need the objects the operating system actually manages. This topic follows the CS162 arc from the four ideas the whole course is built on - the thread, the address space, the process, and dual-mode operation - up through the three abstractions a program touches every day: how processes are created and run, how files and I/O present one uniform interface, and how processes talk to each other through pipes and sockets.

Each page embeds the original lecture and captures the key slides inline, so you can read the notes and jump to the moment in the video where a diagram is drawn.

#LectureWhat it covers
1Four Fundamental OS ConceptsThe OS as an illusionist, and the four ideas everything else rests on: the thread, the address space, the process, and dual-mode (user/kernel) operation with hardware protection.
2Abstractions 1: Threads and ProcessesThe process API - fork, exec, wait, exit - the fork/exec split, and the system-call mechanics that create and run a process.
3Abstractions 2: Files and I/OThe file abstraction, file descriptors and the descriptor table, open/read/write/close, and the single uniform interface behind files, devices, pipes and sockets.
4Abstractions 3: IPC, Pipes and SocketsInter-process communication: pipes, dup2 and redirection, how a shell is built, and the client/server socket API.

How to read these pages

Each page uses a small set of labelled cards, and the label tells you what kind of thing is inside before you read a word:

The card vocabulary
  • Facts - named terms with short definitions.
  • Numbers - the constants and timings worth memorising.
  • Decision - a question with a "pick this when" answer, for choosing between primitives.
  • Gotcha - a trap that causes a real, hard-to-find bug.

The slide images are captured directly from the lecture video and are the work of Prof. Kubiatowicz and UC Berkeley; they are reproduced here for study.

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