CSE 141: Intro to Computer Architecture

Summer Session 2: August 7th – September 9th, 2006 (Section ID 569482)

Vital Info

Announcements

1. Mon Aug 7 14:23:51 PDT 2006
   
   • The course web-board has been activated.
2. Mon Aug 7 23:48:17 PDT 2006
   
   • All registered students should have WebBoard access; use your "UCSD Network User Name" – the user-name name portion of your "@ucsd.edu" e-mail address – as the user name, and your PID number as the password. Please let me know if you have problems logging in, so I can bug the relevant folks to get things fixed. I don't know if they've added the wait-list folks or not.
   • There's some confusion regarding the course textbook. The text is required: on the "schedule" page, you'll find required reading for each lecture, and almost all of the homework is from the book. I'm not going to be checking bookstore receipts or anything, but if you don't have ready access to the text, you may find yourself in a spot of bother.
   • Regarding the wait list: I'll evaluate add requests at the end of this week (or the start of next week), to see if any space has opened up in the roster. Stay tuned.
   • In addition to the assigned reading, printing out the slides and bringing a copy to class is recommended: while I'm scratching through an example on my copy, you can work along. It's more fun than just watching.
3. Wed Aug 9 18:30:12 PDT 2006
   
   • Wait list update: I found out today that waiting-list folks need to have their add cards handed in to the Registrar's office by Friday, which means you'll need them back well before class on Friday. I've asked all wait-listed people who still wish to add the class to give me their add cards in class today, and to pick them up tomorrow, either at my office hour or at the 141L lecture.
4. Fri Aug 11 22:06:09 PDT 2006
   
   • WebBoard / waitlist account update: ACS has manually added the waitlisted students whose add cards I have signed to the WebBoard system. Everyone^(*) should have access now, to the WebBoards, to the basement labs, to LogicWorks, to everything. You can look up your account information, here. If any of these resources don't work for you, please let me know – with details (who, what, where, which computer, etc.) – so I can get the appropriate folks involved.
     (*) Two of you will have to take additional steps for access; I'll e-mail you directly.
   • Homework: please type your homework and staple the pages together before handing them in. No handwritten pages or origami, please. We'll let it slide for homework 1, but will take off points on homework 2.
5. Wed Aug 16 18:48:51 PDT 2006
   
   • I returned Homework 1 at the end of class today. If you haven't already, you may pick yours up from me at my office hour. The average score was 41/50, and nearly everyone turned them in: excellent!
   • Grades: if you're unsure where you went wrong with a homework problem that has been returned, by all means ask a TA, a classmate, or myself. However, the TAs are not able to change your grades; only I can do that. I don't accept appeals for homework regrades, except in the case that a TA made an error while adding up your score. In that case, bring it to my attention so I can fix it.
   • Cheating: I didn't go on and on about this the first day, so here's a final warning: starting with homework two, if someone is found to have cheated on a homework assignment, they will take a zero on that assignment and no further homework will be accepted from them. It takes my time to review the problems, and a lot of TA time and effort to grade them; this is done as a service to you, so don't abuse it. Cheating on exams will be handled more drastically.
6. Mon Aug 21 22:08:41 PDT 2006
   
   • Midterm: the midterm is scheduled for this Friday at 4pm in our usual room. The material covered will come from the assigned ("required") reading, the assigned homeworks, and also anything extra we've covered in lecture by the end of Wednesday. The midterm will be closed-book and closed-notes; we will provide a copy of the MIPS opcode page from the front of your text if it's necessary, so don't waste brain cells memorizing opcodes. (You should be familiar with the MIPS instruction formats and common instructions by now, of course.)
   • Yes, there will be a homework due Friday.
   • Homework 2 has been returned. The average was 46, with 48 of 49 folks turning it in: excellent!
   • Slides: by popular demand, I've posted a "one up" – one slide per page – version of the pre-class slides. See the schedule page. I'm still working on getting an "inked" version exported from the presentation software; apparently that feature isn't built-in. (They didn't expect folks to export?) This is unfortunately low-priority.
   • Free food, and fun with gadgets! This week on campus, the Ubiquitous Presenter team is holding several events experimenting with new modes of classroom interaction. You get to come and play with gadgets, and will be rewarded with free pizza and brownies for your trouble! These are the folks who have generously supplied the tablet PC being used in your CSE 141 and CSE 141L courses, which would be a lot less nice if I spent the time scratching away at the blackboard instead. So, help 'em out. For more info, see the announcements, here(1) and here(2).
7. Mon Aug 28 21:24:35 PDT 2006
   
   • Homework 4 Changed: I've added some more exercises to this homework. Be sure not to leave them out.
   • TA swap: Will and Steve will swap discussion sections this week. Steve will not hold office hours tomorrow, either.
8. Tue Aug 29 12:08:03 PDT 2006
   
   • Homework 4 Bugfix: There's been small change to exercise 5.36, due to a "bug" in the original text; see the homework page. Sorry for the late change.
9. Wed Aug 30 21:13:24 PDT 2006
   • Midterm return: the midterms have been graded. I will have them available at my office hour on Thursday, as well as after class on Friday. The mean was 56.4, population standard deviation 16.0, max 86.
10. Tue Sep 5 18:20:14 PDT 2006
    • Steve will have extended office hours (tomorrow, Wednesday the 6th) from 6pm to 8pm.
11. Fri Sep 8 19:14:24 PDT 2006
    • Caching low-down: Everyone, I'm sorry I didn't manage time well enough for a good treatment of caching at the end. Talking to folks and looking at homeworks, I realize now that the "word address" business from the textbook may have actually done more harm than good. For that reason, and for the folks who missed class trying to finish their labs, here's the low-down on practical, power-of-two cache addressing:
      1. Use byte addresses! I recommend against using "block addresses" and "word addresses" as in the text, it's too confusing.
      2. To get the tag and index bits from an address, you slice the binary value of the address into three pieces, bit-wise: tag bits on the left, index bits in the middle, and block-offset bits on the right.
      3. The data addresses held in a cache block are aligned to the block size; e.g., for a block size of 64 bytes, the first byte address of any block is a multiple of 64. One simple way to take a byte address and calculate the first byte address in its containing block is to set its offset bits to zero.
      4. The index – the value of the index bits – selects the "set" or "row" number to test. The tag bits are used for matching only within that set. There's no need to store the starting address of each block in the cache itself, since the starting address has the value of the tag bits, concatenated with the index bits, concatenated with a block offset of 0; a tag match within the correct set implies can only occur if all of these bits match, which is why we store tags instead of the entire starting address.
      5. # block offset bits = log2(block size in bytes)
         # index bits = log2(number of "sets" or "rows")
         # tag bits = all remaining bits on the left. For MIPS, this would be (32 - (# index bits) - (# block offset bits))
      6. total data size = (block size) * (total #blocks)
         total #blocks = #sets * associativity
         for direct-mapped, associativity = 1
         for fully-associative, associativity = #blocks
         additional storage overhead: tag bits, valid bits, LRU/NMRU/etc. bits
      7. In the examples from lecture, "sets" were shown as rows in a 2D table; every index corresponded to one row. The associative "ways" within each "set" were shown as columns.
12. Fri Sep 8 19:21:38 PDT 2006
    • Homework 5 graded at lightning speed: with the final and the labs, we have no time or people available to grade homework #5. It was also somewhat shady to assign the homework in advance of the corresponding lecture. Really, I just wanted to ensure people spent time thinking about caching, and had practice manipulating caches. So, if you turned in homework #5 with answers for at least four of the seven exercises, your score is 50/50. Best of luck on the final!!