$osOperating Systems

Operating Systems · Lectures 1 to 8

Learn OS by doing.Read a lecture, run the idea,get marked on it.

Your eight lectures rewritten as clear notes with every worked example, plus simulators and quizzes so you can check you actually understood before the exam does.

Start with Lecture 1 Browse the labs
8 lectures190 quiz questions6 labsWorks offline, saves in your browser
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Start here

New here? Read Lecture 1, then take its quiz.

Each lecture takes 20 to 75 minutes. Mark it done at the bottom, take the quiz, then open its lab. Your progress is saved in this browser.

Start Lecture 1
  1. L1Intro
  2. L2Syscalls
  3. L3Structures
  4. L4Processes
  5. L5Queues
  6. L6CPU sched
  7. L7Threads
  8. L8Deadlock

The lectures

Eight lectures, in the order they were taught.

Each one has notes, diagrams, worked examples, a quiz, and a lab where there is something to simulate.

System structures

L1

Introduction to Operating Systems

What an operating system is, how the hardware underneath it is organised, why the OS runs in two modes, and the five classic types of OS with their trade-offs.

40 min read · 22 questionsOpen
L2

System Calls and Interrupts

How a user program asks the kernel for help through system calls, the five categories of calls with their Windows and Unix names, and how hardware and software interrupts pull the CPU into the OS.

35 min read · 20 questionsOpen
L3

OS Design, Implementation and Structures

How you decide what an OS should be (user vs system goals, policy vs mechanism), the five ways to arrange a kernel from MS-DOS to loadable modules, and the six kinds of system programs that live on top.

30 min read · 21 questionsOpen

Process management

L4

Processes and Operations on Processes

What turns a program on disk into a running process, how its memory and state are organised, what the PCB stores, and the UNIX lifecycle of fork, exec, wait and exit, including zombies and orphans.

55 min read · 23 questionsOpen
L5

Process Scheduling

How the OS keeps the CPU busy: the queues a process moves through, the three schedulers that move it, and the cost of every context switch.

30 min read · 20 questionsOpen
L6

CPU Scheduling

Every CPU scheduling algorithm on the syllabus, each with the slide's worked example reproduced number by number: FCFS, SJF, SRTF, priority, round robin, multilevel queues, and multiprocessor scheduling.

75 min read · 32 questionsOpen
L7

Threads

What a thread is, what it shares and what it owns, why threads beat processes for many jobs, and how user threads map onto kernel threads in the many-to-one, one-to-one, many-to-many, and two-level models.

35 min read · 20 questionsOpen

Deadlock

L8

Deadlock

Why processes freeze forever waiting on each other, the four conditions that make it possible, resource-allocation graphs, and the three ways out: prevent it, avoid it with the Banker's algorithm, or detect and recover.

60 min read · 32 questionsOpen

Practice

Reading is not enough. Run it.

Every lab starts with a three-step guide and a suggestion for what to try first, so you are never staring at an empty control panel.

Lecture 6

Scheduling simulator

Watch FCFS, SJF, SRTF, priority and round robin build a Gantt chart, then get marked on random problems.

Open
Lecture 4

fork() terminal

Run C programs with fork, exec and wait in the browser. See every process and count them.

Open
Lecture 8

Deadlock lab

Step through the Banker's algorithm and find cycles in a resource-allocation graph.

Open
All lectures

OS shell

Type man deadlock, sched, or quiz. A friendly fake terminal for quick revision.

Open
1

Read

One lecture at a time. Notes, pictures, worked numbers, predict-the-output cards.

2

Run

Open the lab linked from that lecture and play until the behaviour feels obvious.

3

Get marked

Take the lecture quiz, then exam mode across lectures. Wrong answers come with explanations.