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CO527 Anonymous Questions and Answers |
This page lists the various questions and answers. To submit a question, use the anonymous questions page. You may find the keyword index and/or top-level index useful for locating past questions and answers.
We have taken the liberty of making some minor typographical corrections to some of the questions as originally put. Although most of the questions here will have been submitted anonymously, this page also serves to answer some questions of general interest to those on the course.
Submission reference: IN1862
What is the average air-speed velocity of an unladen student?
About 145 m/s.
Submission reference: IN3375
I do not have access to the 2012/2013 CO324 powerpoint slideshows because I was not enrolled at this time. My 2013 moodle no longer had any of the slides to this module either. How do we get access to the information to revise the CO324 Operating Systems module?
The link for 2012/2013 was wrong (carried over from last year), so I've pointed this at the 2013/2014 version of CO324. But as you say, this is missing the content..! I'll ask Bob to see if this can be put back.
Submission reference: IN3374
Are the slideshow presentations going to be put up on moodle as Powerpoint files too? So far I only see them in PDFs which is not as useful for printing.
Short answer, no. But that's because they weren't done in Powerpoint (if that wasn't obvious!). I can do n-up printable versions, but they don't always come out nicely given the way the individual frames are assembled (the "print" version is the individual frames dumped atop one another). For the time being though I'll make the 2-up versions available.
Submission reference: IN3377
Will the content covered today (first lecture) be on the exam, as you mentioned it is background content, or is it to help build understanding of things to come?
The material covered today is not directly examinable (rather, won't be directly examined). I.e. you won't encounter any questions such as:
Though these might be good questions! Its inclusion is to allow you to build a better understanding of what comes later, particularly to have an insight into what happens at the physical level and what is feasible/infeasible in terms of building a processor architecture. If you took some knowledge or understanding away from today's lecture, that's great :-), but if not, it's not critical — that said, things learned later on may simply remain as facts (e.g. that increasing the frequency of a processor increases power consumption) rather than having an understanding of why (which is because of, amongst other things, the brief periods of short-circuit that occur when switching totem-pole MOSFET structures, and more switching per unit time means more time spent in short-circuit, thus more current draw and more power consumed).
Keywords: electronics
Submission reference: IN3407
Will the content covered in the second lecture (Logic and Designing a CPU) be on the exam?
The material from the slide titled "Designing Our Processor" and onwards is directly examinable. Last year's exam paper is available to give you some idea of what to expect though!
Submission reference: IN3415
What would you suggest we do if we literally don't understand a thing you've been going on about in lectures?
Apologies for my lack of coherence yesterday (and advance warning for today!) but I'm not well :-(. And rescheduling lectures is not a practical option. In general though, and as I said at the beginning, attending the lectures is not enough: you need to be spending time outside the lectures (around 2 hours per lecture I'd say) doing your own reading and learning. I.e. recommended textbooks, Google, Wikipedia, etc. You should be looking to spend a whole day a week on CO527, given it accounts for 25% of your credits this term :-). The content of CO527 is deeply technical (not surprising given the topics) and staying on-top of it might be a struggle (it is a degree you're heading towards, not a GCSE or A-level, so it being difficult in places is not unexpected, and it's hard to be good at everything). Don't, however, make the mistake of thinking that if you memorise all mine and Bob's lecture slides you'll pass the module: most people will need to do more to effect learning.
If people have specific aspects they don't understand, or want clarification, then I'm happy to talk/explain! (if you can catch me in the office, else email, or anonymous questions!).
Keywords: architecture
Submission reference: IN3417
Regarding your lecture today: For most programs, some general data memory is required (somewhere for the contents of variables to be stored). However, previously in the lecture, the slide covering the register file seemed to do this too. Have I got the wrong idea entirely, or can you sometimes use the the register file for the same thing as the SRAM?
Yes, you can. However, bear in mind that the register file only holds 32x 8-bit values, so as long as your program never needs more than 32 values stored simultaneously (including temporaries during calculations) then the register-file would do just fine! The reality is that most programs need substantially more storage, e.g. the SRAM holds 1024x (or 2048x) 8-bit values [depending on the particular AVR device]. One way of looking at it is the register-file being a "cache" for stuff in SRAM, though that's a slightly naive view (the two, at the architectural level and for instruction encoding, are treated differently). There are more subtle differences perhaps, but we'll see those as we get onto programs that actually need to store stuff (e.g. a string of data received from the serial UART).
Keywords: register-file
Submission reference: IN3418
How much of the content of the lectures is extra knowledge that might be nice to know? I am struggling with the module and have put in considerable extra hours and I am still struggling and stressed.
So far, anything related specifically to electricity and/or electronics is background. The assessed content will be the coverage of processing architectures and operating-systems. That does include some aspects of low-level programming, but I'm not expecting people to be expert assembler programmers; rather, to have an understanding of how programs written at that level execute on the architecture (i.e. instruction decoding and data-path). If there are particular aspects you're struggling to understand then please do seek assistance!
Submission reference: IN3416
I'm making a note here:
HUGE SUCCESS.
:-)
Submission reference: IN3429
In the 2014 past paper, question 1a, should we know enough to be able to answer this yet? I can't quite figure it out.
Not yet, but in a couple more weeks you should be able to! The practical session, in particular, should provide some hands-on experience with programming at this level.
Submission reference: IN3442
This might be a silly question, but if SRAM is only accessible in 8-bit chunks but has a 16-bit address space, how do you access an address beyond 2^8?
The relation here is that SRAM is 16-bit (addresses) times 8-bits (=1 byte, each addressable unit). So, although the address you read-from or write-to is given as a 16-bit value (0x0000 through 0x08ff on the ATMega328) what data is read or written is only 8-bits.
Submission reference: IN3451
Not a question, but in the labfile btncode2.asm, lines 242 and 272 are "andi r16, 0x3f", whereas they should actually be "andi r16, 0x38".
Well spotted — mars-bar for you!
Submission reference: IN3515
I'm having difficulty understanding why the amount of physical memory addressable in a system is the page-size * size of a page table entry. Help?
Close, but not exactly: it's the page-size * 2^(PFN-bits-in-PTE). Physical memory is divided into page-frames, each a page big and referred to by its page-frame-number (PFN). The physical location of any page is given by the PFN in some page-table-entry (PTE). Thus, the range of physical addresses that can be generated (or the biggest PFN) is limited by the number of bits available for the PFN in the PTE, and that quantity is 2 raised to the power of the number of bits for the PFN. That limits how many different page-frames can be identified, and thus, how much physical memory can be addressed.
As an example, consider a (daft) machine that uses 8k (8192-byte) pages, but only has 6 bits available in the PTE for the PFN. That means there can only be 64 (2^6) different page-frames, and since each frame is 8k big, the maximum amount of addressable memory is 64*8k = 512k (half a megabyte).
I realise my explanation is a bit wooly, but diagrams are a great asset here.
Keywords: paging
Submission reference: IN3516
In regards to assessment 1, if I complete a try and for example I get 80% for section 1 and 80% for section 2.
On my second attempt, if i get 90% for section 1 and 80% for section 2, what will be my overall grade?
The best combination, which would be the second attempt in this case. Both sections are of equal weight.
Submission reference: IN3523
Can the slides from Lecture 10 please go online ASAP?
Done — sorry about the delay.
Submission reference: IN3519
Can I try the co324 quiz after my 3 tries just for fun/revision?
I'll re-open the quizzes at the end of term for revision purposes, but will keep them locked after the deadline until then.
Submission reference: IN3529
Is there a rough idea of when the practical sessions will take place yet?
Yes! Scheduled and details on Moodle.
Submission reference: IN3554
In regards of the 4th assessment, what are the marking criteria (if possible for each questions)?
I will add some outline marking criteria to the questions. Just a basic mark split though, or I'd give some of it away!
Submission reference: IN3574
Can dates for assessment 4 be in the future?
They could be. But I don't think they are.
Submission reference: IN3599
I don't really understand two second periods. I understand how to get them, but dont they give 3 possible seconds the file was made in, so for example for the two second period 0, that could be second 0, second 1, or second 2?
No...if the number comes out at 0, then the value is 0. If it comes out at 1, the value is 2. If it comes out as (say) 11, then the value is 22.
You just double the value you get.
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Maintained by Fred Barnes, last modified Wed May 25 15:07:20 2016 |
