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# AQA A2 COMP 3 Computing 2015 - Official Thread watch

1. Can I just say how much I hate A2 Computing.

I've completed all the past papers (and the specimen), and the mark schemes are giving contradictory answers. One, the specimen mark scheme, states a bubble sort is:

and goes onto say that this is because adjacent pairs are compared and perhaps swapped, and you may have to continue until the end of list.

Although the 2012 mark scheme says that a bubble sort is because there is a nested loop and the basic operation is the if statement (which I agree with).

I just don't understand what they expect us to write?
2. (Original post by Robbo54)
Can I just say how much I hate A2 Computing.

I've completed all the past papers (and the specimen), and the mark schemes are giving contradictory answers. One, the specimen mark scheme, states a bubble sort is:

and goes onto say that this is because adjacent pairs are compared and perhaps swapped, and you may have to continue until the end of list.

Although the 2012 mark scheme says that a bubble sort is because there is a nested loop and the basic operation is the if statement (which I agree with).

I just don't understand what they expect us to write?
Nested loops are n^2.
Yeah, I'll agree with that & thats how it worked for me. Just thought some people might want to watch them because they are of a passing interest.
Yeah yeah sure dw, I find their video pretty interesting to watch. They've taught me so much to do with Computing. Especially Tom Scott .
4. (Original post by Async)
Yeah yeah sure dw, I find their video pretty interesting to watch. They've taught me so much to do with Computing. Especially Tom Scott .
Yeah I really like Tom Scott's videos - have you subscribed to his own YouTube channel, his Things You Might Not Know series is really good.
Yeah I really like Tom Scott's videos - have you subscribed to his own YouTube channel, his Things You Might Not Know series is really good.
Waay ahead of you on that one Subed ages ago..

Tbh I think he knows a bit too much
6. (Original post by Async)
Waay ahead of you on that one Subed ages ago..

Tbh I think he knows a bit too much
Haha yes!! Who knows how he knows so much.
7. Hi everyone, I found this list of questions from the old specification that our still on our spec.
Problem is I can't find the markschemes to the questions, but it should be useful anyway:

COMP 3 Old Spec Questions v2.pdf - 14.0 MB

If anyone find the markschemes please post back.
Thanks
8. Can someone explain what logic levels are in terms of asynchronous data transmission. In the Nelson Thornes textbook it states that "Typically the idle state is high (logic level 1) so that a broken cable can be deleted but be prepared to be asked questions where the idle state is low (logic level 0)".

What are logic levels and what's the difference between levels?
9. (Original post by PancakePIC)
Can someone explain what logic levels are in terms of asynchronous data transmission. In the Nelson Thornes textbook it states that "Typically the idle state is high (logic level 1) so that a broken cable can be deleted but be prepared to be asked questions where the idle state is low (logic level 0)".

What are logic levels and what's the difference between levels?
My version of the textbook simply refers to them as voltage levels - the more logic levels (states), the greater the number of different voltages the wire can be at.

In the specification, for asynchronous data transmission only two states / logic levels - which correspond to the binary 0 and 1 values that you see.

Also: Apparently they still haven't changed the typo in the textbook, "deleted" should be "detected".
10. Do you need to learn the pesudo-code for algorithms like Binary search, Insertion sort and Quicksort?

Cause I don't think i can muster the strength to learn them at this stage...
11. (Original post by TabbyGuy123)
Do you need to learn the pesudo-code for algorithms like Binary search, Insertion sort and Quicksort?

Cause I don't think i can muster the strength to learn them at this stage...
I highly doubt it, any pseudo-code that you have to interpret will be manageable on the day. Don't fret about learning pseudo-code for algorithms.
12. (Original post by TabbyGuy123)
Do you need to learn the pesudo-code for algorithms like Binary search, Insertion sort and Quicksort?

Cause I don't think i can muster the strength to learn them at this stage...
Learn how they work don't memorize them. The often ask you to implement algorithms of some routines or adt, like I've seen a question they asked for us to implement a Queue or Stack and we had to write the pseudo code for it
13. Does anyone ever get full marks on the E-R diagram questions? I always drop at least one because I make a mistake somewhere, does anyone have any resources?
14. Hi guys how are you all revising for this?
15. Ah okay thanks guys
16. (Original post by Theman69)
Hi guys how are you all revising for this?
Going to go over the spec today and tomorrow. Monday should be just pure past papers.
17. (Original post by BaronK)
Going to go over the spec today and tomorrow. Monday should be just pure past papers.
Yeah thats what I'm doing too
18. (Original post by Robbo54)
Does anyone ever get full marks on the E-R diagram questions? I always drop at least one because I make a mistake somewhere, does anyone have any resources?
Is this the questions where you have to draw the degree on the relationship on the diagram (drawing lines between the boxes)?

I find it easiest to look at the foreign key fields in the relations which are normally listed in the stem of the question. If you see a foreign-key in relation (A) that references the primary key in relation (B) draw a line. If you see another foreign key in (B) that references the primary key in (A) (the other way around) then its 1:1 otherwise its 1:many. You will only find many:many relations through a join table where 2 x 1:many relations make a many:many but normally you don't need to draw this one.
but normally you don't need to draw this one.
You should remember though they normally give you the mark for implied relationships i.e. Many:Many, unless the question is very specific.
20. (Original post by BaronK)
Going to go over the spec today and tomorrow. Monday should be just pure past papers.
When you say going over the spec do you have a list or do you mean go through the textbook?

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