AQA A2 COMP 3 Computing 2015 - Official Thread

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:

O(n^2)

and goes onto say that this is because

n-1

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

O(n^2)

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?

(edited 8 years ago)

Reply 221

BaronK

9

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:

O(n^2)

and goes onto say that this is because

n-1

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

O(n^2)

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.

Reply 222

Async

19

Original post by helloinvader

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 :colone:

.

Reply 223

helloinvader

2

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 :colone:

.

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.

Reply 224

Async

19

Original post by helloinvader

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 :wink:

Subed ages ago..

Tbh I think he knows a bit too much

Reply 225

helloinvader

2

Original post by Async

Waay ahead of you on that one :wink:

Subed ages ago..

Tbh I think he knows a bit too much

Haha yes!! Who knows how he knows so much. :biggrin:

Reply 226

JamGrip

1

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

Reply 227

PancakePIC

1

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?

Reply 228

helloinvader

2

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".

(edited 8 years ago)

Reply 229

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...

(edited 8 years ago)

Reply 230

Shaney96

7

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.

Reply 231

Async

19

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

Reply 232

Robbo54

2

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?

Reply 233

Theman69

Hi guys how are you all revising for this? :smile:

Reply 234

TabbyGuy123

Ah okay thanks guys :smile:

Reply 235

BaronK

9

Original post by Theman69

Hi guys how are you all revising for this? :smile:

Going to go over the spec today and tomorrow. Monday should be just pure past papers.

Reply 236

TabbyGuy123

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

Reply 237

helloinvader

2

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.