CS3650 - Computer Systems

Fall 2020

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


01SH 42511:45am-1:25pm Mo/Th
03SH 3352:50pm-4:30pm Mo/We

In person class meetings are optional. You can find Zoom links for remote participation on Canvas.

Profs Alden Jackson and Gene Cooperman are also offering sections of the course. These sections will vary somewhat in assignments and topics.

Staff & Office Hours

Nat TuckMS TeamsWe 1pm-2pmntuck ⚓ ccs.neu.edu
Amitesh DeshpandeMS TeamsTh 5pm-6pmdeshpande.am ⚓ northeastern.edu
Samarth ParikhMS TeamsTh 10am-11amparikh.sam ⚓ northeastern.edu
Vikas VeerabathiniMS TeamsTu 5pm-6pmveerabathini.v ⚓ northeastern.edu
Ishani KapoorMS TeamsMo 11:30am-11:30amkapoor.i ⚓ northeastern.edu
  • Office hours run from September 14th to Dec 16th.
  • Cancellations and changes may be posted to Piazza.

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 provided as pre-recorded videos at the beginning of each week.
  • Our scheduled in person meetings are optional, and will consist of live demos of material related to the week's lecture topic as well as live Q&A.
  • In person meetings may end early if we run out of questions.
  • Each student will be expected to attend at most one in person meeting per week.
  • It may be possible to view the in person meetings and ask questions remotely live using video chat software, but they will not be recorded due to privacy concerns.
  • There will not be scheduled in-person office hours. Instead there will be online office hours only.

Make sure you are familar with the university policies for being on campus and attending classes during the COVID-19 pandemic.

Specifically, keep in mind the following for our in-person meetings:

  • Everyone is expected to wear a mask.
  • Everyone is expected to maintain six foot social distancing.
  • Keeping masks on means no food in class.
  • Maintaining six foot distancing will mean that entering and leaving the classroom takes extra time. Make sure to arrive on time.


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, on Canvas, and on Inkfish. Only the assignments and due dates listed on Inkfish matter.

WeekStartsTopicsWork Due
1Sep 07 (α)Intro: Systems & Assembly-
2Sep 14ASM: "Design Recipe"; Large ASM Example;HW01: Linux Setup & Hello Worlds
3Sep 21ASM: Syscalls, I/O, the heap; Processes & MemoryHW02: ASM, Pointers, Funs
4Sep 28C: Arrays & Pointers; C: Data Structures;HW03: ASM Sort
5Oct 05A Simple Tokenizer; Syscalls: fork, exec, waitpid;HW04: C Data Structures
6Oct 12 (β)Building a Shell & pipe; read, write, proc table, vmem;HW05: Shell Tokenizer
7Oct 19shared mem & data races; semaphore locks & deadlock;CH1: Unix Shell
8Oct 26threads and mutexes; cond vars and atomicsHW06: Parallel Sort (Processes)
9Nov 02malloc: free lists; malloc: optimizations & threads;HW07: Parallel Sort (Threads)
10Nov 09 (γ)Garbage Collection; OS KernelsHW08: Simple Memory Allocator
11Nov 16Looking at xv6; Disk HardwareCH2: Advanced Memory Allocator
12Nov 23 (δ)File Systems: FAT; File Systems: extHW09: Examining xv6
13Nov 30The FUSE API; Concurrency solutionsHW10: Simple FS
14Dec 07 (ε)Wrap Up; Last class MondayCH3: Advanced FS
  • (α) No meeting Monday: First week
  • (β) No meeting Monday: Colombus day
  • (γ) No meeting Wednesday/Thursday: Veterans' Day
  • (δ) No meeting Wednesday/Thursday: Thanksgiving
  • (ε) No meeting Wednesday/Thursday: Last Week


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 professor's office hours to discuss how you can catch up.

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

First, go to the office hours of 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.

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.
  • Scores must be contested within two weeks of the grade being posted to Inkfish, and no later than Wednesday of finals week.
  • Leftover tokens give you a small bonus to your final grade.

Special Accomodations

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

If you have been granted special accomodations either through the DRC or as a student athlete, let me 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 Plagarism 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.