Click here to see a PREVIEW of important rules that was posted before the semester started.

This is an undergraduate course on computer operating systems. (But only graduate students are permitted to be in this class. USC undergraduate students must take CS 350 in order to get credit for OS. If you are an undergraduate student, you cannnot be in this class and you cannot get credit for Operating System if you take this class. Please check with your adviser to see which Operating System class you need to take!) In addition to exploring concepts such as synchronization, virtual memory, processes, file systems and virtualization, students will develop elements of a fairly complete operating system during the course of the semester.

Instructor Bill Cheng (click to see office hours)
E-mail: <>.  (Please do not send HTML-only e-mails. They will not be read.)
  DEN Section (29945D+29946D) AM Section (30203D) PM Section (30243D)
Time MW 10:00am - 11:50am  TT 9:30am - 10:50am  TT 12:30pm - 1:50pm 
Location (online)  (online)  (online) 
TA Ben Yan, E-mail: <>
Office Hours: Thu 7:00pm - 9:00pm on Zoom
Zhuojin Li, E-mail: <>
Office Hours: Mon 3:00pm - 5:00pm on Zoom
Zhuojin Li, E-mail: <>
Office Hours: Mon 3:00pm - 5:00pm on Zoom
Aditya Chandupatla, E-mail: <>
Vinitha Raj, E-mail: <>
(If needed, the grader will hold office hours the week after the announcement of each assignment's grades.)
Midterm Exam during class time, Wed, 10/7/2020 (firm) during class time, Thu, 10/8/2020 (firm) during class time, Thu, 10/8/2020 (firm)
Final Exam 8am-10am, Mon, 11/23/2020 (firm). 8am-10am, Thu, 11/19/2020 (firm). 11am-1pm, Thu, 11/19/2020 (firm).
Class Resources
Description   :   textbooks, topics covered, grading policies, additional resources, etc.
Lectures   :   information about lectures (and lectures slides in PDF format).
Videos   :   information about DEN lectures and discussion sections videos.
Discussions   :   information about discussion sections.
Projects   :   programming assignments (please also see important information about the class projects below.)
Forum   :   Google Group online forum for discussing course materials and programming assignments. All important announcements will be made using this online forum. Therefore, you are required to be a member of this group. (This group is by invitation only and you need to make sure that you are a member.) Please do not send request to join this group until after Lecture 1.
(in reversed chronological order)
  • 9/6/2020:
    • Below is the grade normalization information for warmup1. Please note that this only applies to the grader-dependent part of your grade. If you are graded by Aditya Chandupatla <>, his warmup1 average was 88.70 with a standard deviation of 20.90. If you are graded by Vinitha Raj <>, her warmup1 average was 88.68 with a standard deviation of 20.47. The overall class average for warmup1 was 88.69 with a standard deviation of 20.70.

      To figure out your normalized score for warmup1, here's what you can do. If your grader-dependent part of your grade is X and your grader's average is A with a standard deviation of D, then Y=(X-A)/D is the number of standard deviations away your score is from your grader's average. Therefore, your normalized grader-dependent part of your grade would be 88.69+Y*20.70 (i.e., same number of standard deviation away from the overall class average). Your minimum score is still one point if you have submitted something for grading.

      As I have mentioned in Lecture 1, although we assume that we have a bell-shaped curve, when your score is normalized, linear interpolation is used. It's clearly not perfect since the actual curve will never be bell-shaped and linear interpolation is not the same as bell-shaped-curve interpolation. But this is what was announced at the beginning of the semester, and therefore, we will stick to this particular way of normailzation for all the programming assignments for the rest of the semester, knowing that it's not perfect.

  • 8/31/2020:
    • I have to cancel tomorrow's office hour (9/1/2020) because I have to be at a meeting. Sorry about the inconvenience. If you have questions about warmup2, please send me e-mail.

  • 8/25/2020:
    • I have always known that Android runs on top of the Linux operating system, but I have never "seen" that Linux system until today! You can download an Android app called Termux from the Google App Store. If you install it and run it on your Android phone, you can get a "bash" shell and it looks just like the Ubuntu Terminal program (without the fancy graphical user interface)! Try a few Linux commands (e.g., "ls -a", "ps", "pwd", "whoami", "cat .bash_history"). They all work!

  • 8/20/2020:
    • When you log into D2L and try to access a lecture video, if you get an error message saying, "You do not have access to this session", here's the solution posted on the D2L web site today.
      Encounteirng Panopto Video Error: You do not have access to view this session

      [ Posted Aug 20, 2020 10:40 AM to USC Viterbi School of Engineering ]

      Hello fall 2020 students! If you encounter this error below while attempting to stream or download a lecture video (the highlighted red box), please DO NOT select the "request access" link (because that's not the problem).

      Instead, please log out of Panopto (clicking your name, ex: the highlighted green box on the top right). Then, clear your cache, ensure cookies are permitted for Panopto/D2L, and log back in.

      If you are running any ad-blocker browser extensions, please ensure that Panopto & D2L are whitelisted.

      If the problem persists, please screenshot the error and send an email to <>.

  • 8/17/2020:
    • During today's live DEN section lecture, I had to admit some student manually and I didn't have time to verify if these students are registered students or even if they are USC students! Due to security concerns, I cannot do things like that in the future. Starting tomorrow, if you want to join a Zoom lecture or office hour, you must sign on to Zoom using USC SSO (i.e., just like you log into USC e-mail through the shibboleth authentication page). If you sign in that way, you will go directly to the Zoom meeting (and bypass the waiting room). If you do not sign in this way, I will not admit you into the Zoom meeting because I have no way to authenticate you during a live Zoom meeting and I cannot violate our security policy.

      Also, I changed the setup for live lectures so that students cannot join the Zoom meeting before I start the meeting. Starting with tomorrow's live lectures, I will start the Zoom meeting a couple of minutes before the scheduled start time. Therefore, you will not be able to join the meeting more than 2 minutes before the scheduled start time.

  • 8/9/2020:
    • Watch this area for important announcements.

    • To get user ID and password for accessing protected area of this web site, please visit the request access page after semester starts and submit the requested information. (You do not have to be registered for the course to get the password. You just need to have an USC e-mail address.)

    • Please do not send request to join the class Google Group until after the Lecture 1.
Some people mistakenly think that this is an introductory CS class! This class has CS prerequisites! In the official syllabus, it is listed that the prerequisites are:
(CSCI 201L or CSCI 455x) and (EE 357 or EE 352L)

Please see:

Apparently, they are the prerequisites for undergraduate students only. The CS department would waive these prerequisites for graduate students. Since undergraduate students are required to take CS 350 for OS credit, there should only be graduate students enrolled in CS 402. Therefore, these prerequisites are really not prerequisites. They should be considered recommended preparation for graduate students. The basic idea behind these prerequisites is that you are expected to know how to program and you are expected to know something about computer architecture (such as what a CPU does).
The programming assignments of this class will be very demanding. You will be required to write C code. Since C is a proper subset of C++, knowing C++ well would give you enough background. However, some of the things that available in C++, such as strings and streams, are not be available in C. So, you need to know how to do things such as manipulating null-terminated array of characters (using functions such as strchr, strrchr, strlen, strcmp, strncpy, etc.) and performing console and file I/O (using functions such as printf/snprintf, fread/fwrite, read/write, fgets, etc.) in C. No other programming language will be accepted. We will not teach C in this class. You are expected to pick up C on your own if you are not familiar with it.

You should also get familiar with the Unix/Linux development environment (vi/pico/emacs, cc/gcc, make, etc.) You are expected to know how to use Unix/Linux. If you are not familiar with Unix/Linux, please read Unix for the Beginning Mage, a tutorial written by Joe Topjian. You can also visit UNIX Tutorial for Beginners or Learn tcsh in Y Minutes. If you knew how to use Unix/Linux before and just need a refresher, please review a summary of some commonly used Unix/Linux commands.

All programming assignments must run on 32-bit Ubuntu 16.04. The kernel programming assignments will only work on a 32-bit Ubuntu 16.04 system. Therefore, you should install a 32-bit Ubuntu 16.04 on your laptop or desktop as soon as possible and start using it right away. If you do not have a personal laptop or desktop that runs Windows or Mac OS X, please contact the instructor as soon as possible. If you are considering buying a laptop, please buy an Intel-based laptop that runs Windows or Mac OS X.

If a student registered late for this class or could not be present at the beginning of the semester, the student is still required to turn all projects and homeworks on time or the student will receive a score of 0 for these assignments. No exceptions!