CSE 120: Principles of Computer Operating Systems

Fall 2023

Geoffrey M. Voelker (voelker@cs.ucsd.edu)
Tu/Th 8–9:20am
Mosaic 0113
TAs and Tutors
William Lin Yunxiang Chi
Charlotte Tang Edward Jin
Kaiyuan Wang Jong Hyun Park
Hui Zhi Xiyan Shao
  Timothy Wu
Discussion Sections
Fri 9–9:50am in Mosaic 0114
Office Hours
Voelker: Mon 3–4pm, Wed 4–5pm (CSE 3108)
Lab Hours
TA/tutor calendar
Discussion Board
Lab Hours
Remzi H. Arpaci-Dusseau and Andrea C. Arpaci-Dusseau
Operating Systems: Three Easy Pieces
Version 1.00   (Available free online!)

Course Objectives

This course covers the principles of operating systems. It emphasizes the basic concepts of OS kernel organization and structure, processes and threads, concurrency and synchronization, memory management, file systems, and communication. It is also a project course, providing essential experience in programming with concurrency, implementing and unmasking abstractions, working within an existing complex system, and collaborating with other students in a group effort.

Course Schedule

The following table outlines the schedule for the course. We will update it as the quarter progresses.

Date Lecture Readings Optional Homework Project
9/28 Course Intro CH. 1, CH. 2      
10/3 Architectural Support CH. 6 Hardware events HW 1: Out   PR 0: Out  
10/5 Processes CH. 3, CH. 4, CH. 5 Linux context switch    
10/6 (Friday)       PR 0: Due
10/10 Threads CH. 26, CH. 27     PR 1: Out  
10/12 Synchronization CH. 28, CH. 29   HW 1: Due
HW 2: Out  
10/17 Semaphores and Monitors CH. 30, CH. 31 Languages and CVs    
10/19 Semaphores and Monitors CH. 30, CH. 31 Languages and CVs    
10/24 (No lecture, work on project)        
10/26 Scheduling and Deadlock CH. 7, CH. 8, CH. 32      
10/27 (Friday)       PR 1: Due
10/28 (Saturday)     HW 2: Due    
10/30 Midterm Review        
10/31 Midterm Exam        
11/1 (Wednesday)     HW 3: Out PR 2: Out
11/2 Memory Management CH. 15, CH. 16, CH. 18      
11/7 Paging CH. 19, CH. 20      
11/9 Paging (cont'd) CH. 19, CH. 20      
11/14 Page Replacement CH. 21, CH. 22, CH. 23      
11/16 File Systems CH. 37, CH. 39 Interesting behaviors    
11/18 (Saturday)       PR 2: Due
11/20 (Monday)     HW 3: Due PR 3: Out
11/21 File System Implementation CH. 40 Interesting behaviors    
11/23 Thanksgiving Holiday Thanksgiving   Food. Lots of it. Sleep. Lots of it.
11/28 Protection CH. 53, CH. 55   HW 4: Out    
11/30 Virtual Machines Appendix B      
12/5 Research Talk        
12/6 (Wednesday)     HW 4: Due  
12/7 Summary & Final Review        
12/8 (Friday)       PR 3: Due
12/12 Final Exam 8–11am      

Course Organization

The course is organized as a series of lectures by the instructor, discussion sections by the TAs, reading, homework, and project assignments, and exams:


The course will have four homeworks, and I will post them as the quarter progresses. You may type or handwrite your answers, and we will use gradesource for submitting homeworks. To encourage timeliness, we will reduce homework grades by 20% for each day that they are late. But if you run into a difficult situation, let me know.

Due to extensive copying on homeworks in the past, I have changed how homeworks are graded. As long as you submit a technical answer related to the question, you will get full credit for the question. The goal of the homeworks is to give you practice learning the material. The homework questions both supplement and complement the material from lecture and in the project, and you will also find the homework questions to be useful for practicing for the exams. We will post solutions to all homeworks after they are submitted, and you can use them for studying as well. But, even with the solutions, the amount you learn from the homeworks will be directly correlated with your effort working on them.

I encourage you to collaborate on the homeworks: You can learn a lot from your fellow students. Collaboration consists of discussing problems with other students and independently writing your own answers to the problems based upon those discussions. As a rule of thumb, you should be able to discuss a homework problem in the hall with others, go home, and then write up your answer to the problem on your own.


The course has one tutorial project and three programming projects using the Nachos instructional operating system.


The course has two exams, a midterm and a final. The midterm will cover the first half of the class, and the final will cover the material for the entire quarter. Below are sample exams to help you study.

Discussion Sections

Discussion sections answer questions about the lectures, homeworks, projects, and programming environment. They may also supplement the lectures with additional material.


Your grade for the course will be based on your performance on the homeworks, midterm and final exams, and the three projects using the following weights:

The academic honesty guidelines outlined by Charles Elkan apply to this course. I urge you to resist any temptation to cheat, no matter how desperate the situation may seem. If you are in circumstances that you feel compel you to cheat, come to me first before you do so. Examples of cheating include copying code or answers from someone else, copying code or answers from online sources, or using generative AI or LLMs.

Supplemental Reading

The supplemental readings include primary sources and in-depth supplements for concepts in the class. Supplemental reading is for your own interest — the readings are not required, nor will you be tested on the material. Note that some of the links to the documents point to the ACM Digital Library. UCSD has a subscription to the ACM Digital Library, so you will need to use a web browser on campus to access them.