uwloo

CS 251Computer Organization and Design

Units
0.50
Faculty
Mathematics
Subject
Computer Science

When it runs

  1. F24
  2. W25
  3. S25
  4. F25
  5. W26
  6. S26
  7. F26
  8. W27
  9. S27

Ran in 7 of the last 7 terms. Winter 2027: scheduled, 3 lecture sections. Spring 2027: schedule not out yet.

Overview of computer organization and performance. Basics of digital logic design. Combinational and sequential elements. Data representation and manipulation. Basics of processor design. Pipelining. Memory hierarchies. Multiprocessors.

Prerequisites

Antirequisites

  • Complete all of the following
    • Not completed nor concurrently enrolled in any of the following:
      • BME393 - Digital Systems (0.50)
      • CS251E - Computer Organization and Design (Enriched) (0.50)
      • ECE222 - Digital Computers (0.50)
      • ME262 - Digital Logic, Microcontrollers, and Programmable Logic Controllers (0.50)
      • MTE262 - Introduction to Digital Logic (0.50)
    • Not completed any of the following:

Leads to

Fall 2026 sections

Enrolment from UW Open Data, which can trail Quest by up to two days. Instructors and rooms: Schedule of Classes.
SectionClassEnrolledMeets
LEC 001600071 / 90TTh 10:00–11:20
LEC 002621472 / 90TTh 13:00–14:20
TUT 101658874 / 90W 13:30–14:20
TUT 102658969 / 90W 15:30–16:20
TST 2016545143 / 180Nov 12 16:30–18:20

Winter 2027 sections

Enrolment from UW Open Data, which can trail Quest by up to two days. Instructors and rooms: Schedule of Classes.
SectionClassEnrolledMeets
LEC 00156040 / 100TTh 11:30–12:50
LEC 00257990 / 100TTh 13:00–14:20
LEC 7012182158 / 9999Online or by arrangement
TUT 10161100 / 100W 13:30–14:20
TUT 10261110 / 100W 14:30–15:20
TST 20156820 / 200Mar 11 16:30–18:20

Resources

Around the web

Found by uwloo’s link finder, which checks that each page names CS 251.

Suggest a resource.

Reviewed on UW Flow

63% liked it78% easy66% useful

From 518 ratings and 127 comments on UW Flow. The most helpful comments, quoted as written, without names. Read them all on UW Flow.

  • Tl;dr the assessments suck in this course.
    A lot of the concepts themselves are pretty cool, but the course is designed quite poorly in the way they assess your understanding of the concepts. Lots of assignments are fill in the blank and they simply do exact matching to check your answer, so if you made a small mistake near the start, say goodbye to your marks for the entire question! You would think that with humans grading the midterm rather than a computer script, it would be better, but no. Even on the midterm, they mark for exact correctness, and reward very few part marks even if you make the tiniest mistake possible. For reference, one of the multistep questions had us filling in a…

    Apr 2026 · didn’t like it · 5 found this helpfulOn UW FlowRemove this

  • The content itself is okay but the lectures make me want to blow my brains out. Hooooly shit before this course if you told me that it would be possible to inflict Geneva Convention-level psychological warfare on students by talking to them in a singsong kindergarten teacher voice I would not have believed you but now I know better. Ever wondered why, despite Dr. K offering this course for four years straight, there is not a single GOAT who has uploaded detailed lecture notes online for you to read? It's because it is literally IMPOSSIBLE to sit in one of these lectures and translate Dr. K's speech into notes without your brain frying out of your skull. Praise be to that one Flow reviewer…

    Apr 2026 · didn’t like it · 4 found this helpfulOn UW FlowRemove this

  • The content is super interesting, but the delivery is not there man, they should teach this course through simulations or labs, not written assignments

    Apr 2026 · didn’t like it · 3 found this helpfulOn UW FlowRemove this

  • Content: This is one of those courses that starts off easy and gets harder as you go through because the content builds up. Even though the first half is easy, make sure you know the content well. Starts with intro to ARM, moves on to logic gates and transistors, building up to low level circuits. Second half is Single Cycle Processors, Pipelined Processors, and Virtual Memory.
    Exams: Only had 1 this term due to COVID, but it was quite similar to the assignments. Doing the practice problems at the end of the assignments should prepare you thoroughly.
    Assignments: Simple assignments. Each one should take you no more than 2 hours to complete, and a lot of the content is in the slides.…

    Apr 2020 · liked it · 2 found this helpfulOn UW FlowRemove this

  • Boring, the basic routine is spending one class to talk about new stuff , but two more to repeat.

    Jul 2017 · didn’t like it · 2 found this helpfulOn UW FlowRemove this

Discussed on r/uwaterloo

1,039 posts and comments in 701 threads mention CS 251, December 2011 to December 2024. Quoted word for word, newest first; each reply sits under the post and the comment that started its branch. Search r/uwaterloo for newer posts.

Fall 2024

2B CS course selection 2 points, 3 comments

u/Standard-Lecture-950: “… Option 1: CS 246, 245, 251, math 239 in 2B and then CS 240, 241, Stat 231, CS 3xx in 3A 2. …”

u/iamanaybaid555: “Your best combination would be: • CS 246 (pre-requisite for CS 241 and CS 240) • CS 251 (pre-requisite for CS 350) • MATH 239 (pre-requisite for CS 341) • CS 245 (pre-requisite for CS 240) • One elective Two reasons for not taking 231 with this would be a heavier workload and no …”

u/Standard-Lecture-950: “cheers thanks for the really insightful answer - if i was to take cs 251 in place of stat 231, my only concern is that i would have about 4 weekly deadlines for assignments for all of my courses + keeping up with the course content would also need to be done... …”

View on RedditRemove this

CS 246: 85+ Doable 2 points, 5 comments

“Basically what the title says? Is an 85+ doable if I transferred from software eng (took cs 138 which has the same slides as cs246 in the beginning and finished the course with a 93)”

u/Acrobatic_Bite6842: “idk its a pretty hard course. Its realistic to get 90+ on all the assignments if you put the appropriate time and effort into them (its alot) but the exams are pretty hard. …”

u/Professional-Sun4686: “would you say cs 251 or 246 is easier? worried about people's averages dropping for 251 post final”

View on RedditRemove this

Check it elsewhere for Fall 2026

Calendar versions

Undergraduate Calendar