CS3650 - Computer Systems

Spring 2021

This is draft. Information subject to change.

Introduces the basic design of computing systems, computer operating systems, and assembly language using a RISC architecture. Describes caches and virtual memory. Covers the interface between assembly language and high-level languages, including call frames and pointers. Covers the use of system calls and systems programming to show the interaction with the operating system. Covers the basic structures of an operating system, including application interfaces, processes, threads, synchronization, interprocess communication, deadlock, memory management, file systems, and input/output control.

Essential Resources

AMD64 ASM resources


01VeselySH 30511:45am-1:25pm Mo/Th
02TuckSH 3051:35pm-3:15pm Tu/Fr
03TuckSH 3053:25pm-5:05pm Tu/Fr

Office Hours

Office hours will be held online using Khoury Office Hours and Microsoft Teams.

Check the office hours calendar when you're planning your work. Use early office hours and don't rely on being able to get extensive help right before the due date.

Course Staff

Nat Tuckntuck ⚓ ccs.neu.edu
Ferd Veselyf.vesely ⚓ northeastern.edu
Grace Dingding.g ⚓ husky.neu.edu
Ethan Lebaleba.e ⚓ husky.neu.edu
Allison Lisciandrolisciandro.a ⚓ husky.neu.edu
Naveen Muralidharmuralidhar.na ⚓ husky.neu.edu
Jennifer Ribeiroribeiro.je ⚓ husky.neu.edu
Akshat Mansukhlal Savaliyasavaliya.a ⚓ husky.neu.edu
Maxwell Sebsosebso.m ⚓ northeastern.edu
Vincent Zhaozhao.v ⚓ husky.neu.edu
Zach Liebermanlieberman.z ⚓ northeastern.edu
  • Office hours run from January 25th to April 21st.

Pandemic Adaptations / Policies

Due to the ongoing pandemic, we'll be using an altered course structure this semester as well as following the Northeastern policies.

Course structure changes:

  • Primary lecture content will be delivered in synchronous class meetings at scheduled lecture times, available both in-person and remotely by video conference. See Canvas for Zoom links.
  • There will not be scheduled in-person office hours. Instead there will be online office hours only.

Make sure you are familiar with the university policies for being on campus and attending classes during the COVID-19 pandemic. Specifically, you must wear a mask and maintain social distancing in the classroom while those policies remain in effect.


This is an initial schedule, subject to revision as the semester progresses.

Assignments will frequently be due at 11:59pm on Tuesday.

Information about assignments and due dates appear here and on Inkfish. Only the assignments and due dates listed on Inkfish matter.

WeekStartsTopicsWork Due
1Jan 18 (α)Intro: Systems & Assembly; {History}-
2Jan 25ASM: "Design Recipe"; Large ASM Example;HW01: Linux Setup & Hello Worlds
3Feb 01ASM: Syscalls, I/O, the heap; Processes & MemoryHW02: ASM, Pointers, Funs
4Feb 08C: Arrays & Pointers; C: Data Structures;HW03: ASM Sort
5Feb 15 (β){C: Trees}; Syscalls: fork, exec, waitpid;HW04: C Data Structures
6Feb 22Building a Shell & pipe; read, write, proc table, vmem;HW05: Shell Tokenizer
7Mar 01shared mem & data races; semaphore locks & deadlock;CH1: Unix Shell
8Mar 08threads and mutexes; cond vars and atomicsHW06: Parallel Sort (Processes)
9Mar 15malloc: free lists; malloc: optimizations & threads;HW07: Parallel Sort (Threads)
10Mar 22Bonus Topic; OS KernelsHW08: Simple Memory Allocator
11Mar 29Looking at xv6; Disk HardwareCH2: Advanced Memory Allocator
12Apr 05File Systems: FAT; File Systems: extHW09: Examining xv6
13Apr 12The FUSE API; Wrap-UpHW10: Simple FS
14Apr 19 (γ){Bonus Topic}CH3: Advanced FS

The following weeks have no Monday lecture for Section 01. Lectures which are planned only for sections 02 and 03 are listed in {brackets}.

  • (α) No meeting Monday: MLK day
  • (β) No meeting Monday: Pres Day
  • (γ) No meeting Monday: Pats Day

Some possible bonus topics:

  • Garbage Collection
  • High Level Solutions for Parallelism and Concurrency


The textbook for this course is online:

Recommended Readings by Week:

  1. Linux Command Line Tutorial
  2. OSTEP 4
  3. OSTEP 13
  4. OSTEP 13
  5. OSTEP 14
  6. OSTEP 5
  7. OSTEP 15, 16, 18, 31
  8. OSTEP 26, 27
  9. OSTEP 28, 30
  10. OSTEP 17
  11. OSTEP 37, 44
  12. OSTEP 39, 40, 41
  13. OSTEP 43
  14. OSTEP 46, 32, 33

We will also be referring to:


  • Homework: 70% (about 7% each)
  • Challenges: 27% (about 9% each)
  • Misc: 3% (participation, grade challenges, rounding errors, etc)

Percentages are approximate.

Letter Grades

The number to letter mapping will be as follows:

95+ = A, 90+ = A-, 85+ = B+, 80+ = B, 75+ = B-, 70+ = C+, 65+ = C, 60+ = C-, 50+ = D, else = F

There may be a curve or scale applied to any assignment or the final grades, in either direction.

Homework and Challenges

There's a homework or challenge assignment due nearly every week. These assignments will be posted and submitted on Inkfish - make sure to check there for accurate assignment info and due dates.

Assignments in this class is difficult and you are expected to get stuck. Start early so you have time to get unstuck.

Challenges are just like homework, except they're harder, worth more points, and they are graded more harshly. You'll want to start early and plan to spend a lot of time on them.

In order to learn the material in this class you must submit the assignments. If at any point you have three unexcused zero grades for assignments that have been graded you will fail the course.

If you fall behind on the course work for any reason, please come to the instructor's office hours to discuss how you can catch up.

Automatic Grading Script

The Inkfish server will automatically run a test script each time you submit an attempt at an assignment. The output from this script is usually displayed immediately after you upload your code, and your score is displayed at the end of this script output.

Except in the case of a clear mistake by the course staff, this automatically generated grade is your grade for that component of the assignment. You are responsible for waiting for your score to display and making a corrected submission if you want a higher score.

Late Work

Late submissions will be penalized by 1% for each hour late.

For the final assignment, late submissions will not be accepted after the sun comes up in Boston and the TAs start grading.

Late Registration

If you register late for the course please contact the professor for extended homework due dates as soon as possible. In general you will be expected to complete all of your assignments in order, and you will receive an extension on at most one assignment due after your registration date.

Late submissions will be penalized per the normal policy without an explicit written extension from the instructor.


Contesting Grades

Homework and challenge grades will be posted on Inkfish. If you think your work was graded incorrectly, you can challenge your grade through the following process:

First, visit office hours or email the course staff member who graded your work. If you can convince them that they made a concrete error in grading, they will fix it for you.

If the grader doesn't agree that the grade was wrong, you can formally contest your grade with the professor. This follows a variant of the "coaches challenge" procedure used in the NFL.

For automated scripts the staff member responsible is Nat Tuck. Bugfixes to the script can happen whenever, but adjustments to script-generated scores will only happen after the manual component of the grade is posted.

Here's the formal challenge procedure:

  • You start with two tokens.
  • You can spend a token to contest your grade on any assignment.
  • If you have no tokens left, you can't formally contest grades.
  • When you contest a grade, the instructor will regrade your assignment from scratch.
  • The new grade is applied to your assignment.
  • If your new score is higher than the old score, you get your token back.
  • Leftover tokens give you a small bonus to your final grade.
  • Formal challenges must be submitted within two weeks of the grade being posted to Inkfish, and no later than Tuesday of finals week.

Special Accomodations

Students needing disability accommodations should visit the Disability Resource Center (DRC).

If you have been granted special accommodations either through the DRC or as a student athlete, let your instructor know as soon as possible.

Code Copying & Collabaration Policy

Copying code and submitting it without proper attribution is strictly prohibited in this class. This is plagiarism, which is a serious violation of academic integrity.

Providing solution code to other students is also strictly prohibited.


  • For solo assignments, you should personally write your code either from scratch or using only the starter code provided in the assignment.
  • For team assignments, your team should do the same.

Lecture Notes

Lecture notes are not starter code, and should not be copied without attribution. As long as attribution is provided, there is no penalty for using code from the lecture notes.

Collaboration and Attribution

Since it's not plagiarism if you provide attribution, as a special exception to these rules, any code sharing with attribution will not be treated as a major offense.

There is no penalty for copying small snippets of code (a couple of lines) with attribution as long as this code doesn't significantly impact the intended challenge of the assignment. This should be in a comment above these lines clearly indicating the source (including author name and URL, if any).

If you copy a large amount of code with attribution, you won't recieve credit for having completed that portion of the assignment, but there will be no further penalty. The attribution must be obvious and clearly indicate both which code it applies to and where it came from.

Posting Code on the Web

  • You may not post solutions to Homework assignments on the public internet. This will be treated as "Providing Solution Code".
  • Solutions to Challenge assignments in this class can be interesting enough that there's a benefit to posting them publicly (e.g. on Github). You may post solutions to the Challenge assignments on the public internet after your solution has been graded.
  • Some Challenge assignments are also solutions to earlier Homework assignments. Posting solutions to those challenges is OK as long as your code implements a significant portion of the challenge functionality.

Penalty for Plagiarism or Providing Solution Code

First offense:

  • You get an F in the course.
  • You will be reported to OSCCR and CCIS.

Avoid copying code if you can. If you're looking at an example, understand what it does, type something similar that is appropriate to your program, and provide attribution. If you must copy code, put in the attribution immediately, every time or you will fail the course over what feels like a minor mistake.