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AQA COMP3 June 2012 Exam Thread

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Yeh, you'd need override for adding a new device. I didn't put NewDevice in the laptop class definition. I don't know if it needed it, but I didn't see any relevance, I just had function GetBluetoothInstalled or whatever it was

On the note of class definitions, was the RAM and HDD capacity a string datatype????

Reply 521

Darkphilosopher

Original post by mfmdanny

I used GetBluetoothInstalled and SetBluetoothInstalled.

Reply 522

_VJ

Original post by ms607

I thought it was 1.000000 0111

ah yes, that's what the book says ¬¬ don't get why though

Reply 523

Edwin Okli

Original post by exam2k10

On the note of class definitions, was the RAM and HDD capacity a string datatype????

Definitely not string. It gave you the units so you only needed to store numbers, I put float (after putting real). I imagine any number type will probably be accepted.

Reply 524

exam2k10

Original post by Edwin Okli

Definitely not string. It gave you the units so you only needed to store numbers, I put float (after putting real). I imagine any number type will probably be accepted.

Damn! How many marks gone out of 4?

Reply 525

rugito

Original post by mfmdanny

damn it makes sense :tongue:

it should be in the second one.... duno why i put it in

Reply 526

gowans07

For the real number section I put overflow, cancellation and then rounding. The last two I am unsure of but they definatly weren't underflow.

With regards to the rest I was quite happy with it all. Sneaky recursive trace at the end with a poor diagram which was the opposite way round but none the less not a bad paper.

This was posted from The Student Room's iPhone/iPad App

Reply 527

ngnav

got around 70-80 marks, what grade do you think that'll be?

Reply 528

drumdrum

Original post by ngnav

got around 70-80 marks, what grade do you think that'll be?

At least an A, its gotta be. How do you know you have 70-80 marks?

Reply 529

ngnav

Original post by drumdrum

At least an A, its gotta be. How do you know you have 70-80 marks?

Looking back at my answers due the huge surplus we had in time. The pseudocode in this question was absolute bull!!!

Reply 530

mfmdanny

Original post by Darkphilosopher

I used GetBluetoothInstalled and SetBluetoothInstalled.

Would that not be the same?...

Reply 531

Edwin Okli

Original post by gowans07

I'm pretty sure that when you multiply two small numbers you get an underflow error (a number too small to be represented within a certain number of bits). I wrote overflow, underflow and cancellation. Couldn't tell you what order.

Adding a large number and a small number is certainly a cancellation error anyway (I read it in the textbook this morning).

Reply 532

drumdrum

Original post by ngnav

Looking back at my answers due the huge surplus we had in time. The pseudocode in this question was absolute bull!!!

It was, i sat there staring at the algorithm for like 15 minutes, trying to figure it out, i got it in the end though i reckon. Little annoyed there weren't any turing machines, they would have been easy marks :tongue:

Reply 533

Jarred

I mispelt Backus Naur form :colondollar:

. I spelt it as Backaus Naur form. Do you think I'll get the mark? It hardly really matters since it's just one mark, but those one markers add up, and I could do with every mark I can get tbh. Dunno how I did it, my spelling is usually pretty good, think it was pretty much me doing a "typo" with my writing :tongue:

. Only noticed it as my paper was collected. QWC is only marked on the big questions, so is there a chance I'll get the mark since it's clear what I meant?

Reply 534

Darkphilosopher

Original post by mfmdanny

Would that not be the same?...

get = function that retrieves the variable
set = procedure that sets the variable

Reply 535

Edwin Okli

Original post by exam2k10

Damn! How many marks gone out of 4?

Probably just one lost for your fields.

Reply 536

mfmdanny

Original post by Darkphilosopher

get = function that retrieves the variable
set = procedure that sets the variable

Right, yeh, I just saw it in the textbook. Get it now. Damn, lost at least a mark there then :unimpressed:

Reply 537

Prings21

I got these answers. I can't remember the exact questions but hopefully you'll know which ones I mean.

First question: Allocating CPU time, allocating memory, I/O devices

BNF question: Backus Naur Form then No & Yes for the table.

Real numbers question: 1.000000 01111 for most negative number, -44 for the first one and in the table: overflow, underflow & cancellation error.

Algorithm: two outputs (when rope was recognised to clash), n^2 because the there are two loops meaning that there would be n loops that would loop n times and n*n = n^2 or something like that. Then I got space complexity as the alternative to time complexity.

SQL: 1. Composite key 2. no repeating non-key attributes & no non-key dependancies. The two statements were pretty simple although on the 'Insert Into' one it gave the new attributes in a sort of square so you had to be careful to put the attributes in order (I nearly put author before title). The next one I said create another relation like this: Copy(CopyID, BookID) so that each copy was different but you could still get the details of it because it was linked to Book. For the third mark I think you had to say that in loans the foreign key would be changed to CopyID but I said something that the new relation would ensure it passes the referential integrity test so I've probably lost a mark there!

Digital Signatures: 1. Encryption was "the transformation of readable code into cipher code" 2. I put you can't encrypt using A's public key because then no-one can decrypt it so no-one else can read it 3. I put you can't encrypt using A's private key because then everyone can read it because everyone has access to A's public key.

OOP: 1. Diagram was pretty simple. Laptop, desktop, server pointing to computer. Computer and printer pointing to device. My computer definition was:

Computer = Class
Inherits Device
Public
Function GetProcessorName
Function GetHDDCapacity
Function GetRAMCapacity
Private
ProcessorName : String
HDDCapacity : Bytes
RAMCapacity : Bytes
End

For Laptop I got:

Laptop = Class
Inherits Computer
Public
Function GetBluetoothInstalled
Private
BluetoothInstalled : Boolean
End

Not sure about that polymorphism/over-riding you guys were discussing but don't quote me on it! For Bluetooth I put, 'A wireless form of devices communicating with each other, but it has a short range' and the example as 'A laptop sending files to a mobile phone that has bluetooth and is in range'.

Hashing: Can't remember exactly what was said but something like these 1. To ensure the data was secure from hackers. 2. Hashing the data and using the value as a location to store the data in. The actual hashing of the data is the hashing function. 3. When data is hashed to a location that is taken up. Open hashing could be used so the data is stored in the next available location or closed hashing could be used and a pointer field could be created in the hash table and a linked list created starting with that pointer.

The graph question: 1. The property that made it a tree I put down was that there were no unconnected nodes. 2. Mazes could have loops in. 3. Adjacency matrix was quite simple, I got a diagonal line of symmetry which I think you needed for it to be correct. 4. Recursive routine was a routine that has a call to it inside itself. 5. Stack was required to store variables & local parameters, and a stack is suitable because it works on a first in last out method which means the calls would be stored in the correct order.

Halting problem: 1st blank, 'create a program'. 2nd blank, 'without getting stuck in an infinite loop' although I think that was wrong and should have been something along the lines of 'without executing the program'. 3. The importance was that it is an unsolvable problem.

Regex: 1. A(B)+C, don't know whether I needed the brackets or not I put them in just in case. 2. (0|1)1*

That's all I can remember!

Reply 538

rugito

for the class definitions
was the data type for the bluetooth, boolean
and was the other data type for the functions that retrieve in Gigabytes
integer? (i thought of putting bytes but wasn't sure) will i get the mark