CS 3650 - Computer Systems

Spring 2020

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

Inkfish - View and submit homework assignments.
Piazza - Class discussion & announcements.
Linux / Unix Help
scratch - A git repo of stuff that may have happened in lecture.
Nat’s Notes - Probably confusing, but includes most code shown in class.
Online Lectures - This is where you can find the lectures after the course moved online.

AMD64 ASM resources

Sections

Section	Location	Time
02	SH 105	1:35pm-3:15pm Tu/Fr
03	INV 019	3:25pm-5:05pm Tu/Fr

Prof Alden Jackson is also offering a section of the course. His section will vary somewhat in assignments and topics.

Staff & Office Hours

Name	Location	Hours	Email
Nat Tuck	NI 132 E	We 1:30-2:30pm; Fr 5:30-6:30pm	ntuck ⚓ ccs.neu.edu
Kaylin Devchand	HS 118	Mo 6-8pm	devchand.k ⚓ husky.neu.edu
Alec Ge	RY 153	Su 1-3pm	ge.a ⚓ husky.neu.edu
Sneh Gurdasani	SL 009	Mo 11am-1pm	gurdasani.s ⚓ husky.neu.edu
Madhur Jain**	RY 154*	Sa 10am-noon	jain.madh ⚓ husky.neu.edu

(*) RY154 not available on March 14. Alternate location will be announced on Piazza.
(**) Madhur Jain’s office hours don’t start until January 18.
Office hours run from January 8 to April 14.
Cancellations and changes may be posted to Piazza.

Schedule

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

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

Week	Starts	Topics	Work Due
1	Jan 6	Intro: Systems; Intro: Assembly	-
2	Jan 13	ASM: “Design Recipe”; Large ASM Example;	HW01: Linux Setup & Hello Worlds
3	Jan 20	ASM: Syscalls, I/O, the heap; Processes & Memory	HW02: ASM, Pointers, Funs
4	Jan 27	C: Arrays & Pointers; C: Data Structures;	HW03: ASM Sort
5	Feb 3	A Simple Tokenizer; Syscalls: fork, exec, waitpid;	HW04: C Data Structures
6	Feb 10	Building a Shell & pipe; read, write, proc table, vmem;	HW05: Shell Tokenizer
7	Feb 17	shared mem & data races; semaphore locks & deadlock;	CH1: Unix Shell
8	Feb 24	threads and mutexes; cond vars and atomics	HW06: Parallel Sort (Processes)
-	Mar 2	Spring Break	-
9	Mar 9	malloc: free lists; malloc: optimizations & threads;	HW07: Parallel Sort (Threads)
10	Mar 16	Garbage Collection; OS Kernels	HW08: Simple Memory Allocator
11	Mar 23	Looking at xv6; Disk Hardware	CH2: Advanced Memory Allocator
12	Mar 30	File Systems: FAT; File Systems: ext	HW09: Examining xv6
13	Apr 6	The FUSE API; Concurrency solutions	HW10: Simple FS
14	Apr 13	Wrap Up; Last class Tuesday	CH3: Advanced FS

Textbook

The textbook for this course is online:

Operating Systems, Three Easy Pieces

Grading

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. 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

For all assignments except the last challenge, 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 and the TAs start grading.

Late Registration

If you register for the course late, you will have three days to complete each assignment until you are caught up with the rest of the class.

Policies

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.

Details

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.