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AQA A2 COMP 3 Computing 2015 - Official Thread watch

1. (Original post by EllaR97)
I was doing the Jun11 paper and the question asked "what is the smallest positive that can berepresented using normalised floating point system."
I put 0.0000001 with exponent of 1000, but the markscheme says 0.1000000 with exponent of 1000 - anyone know why?

Wikibooks agrees with me :-S

:-)

I understand why you would arrive at that answer, the reason the mark scheme says its 0.1000000 with exponent of 1000 is because the answer is normalised.

The answer you gave makes logical sense but seeing as your sign bit is 0 and the following bit is also 0 (0.0) the answer isn't normalised. They tend to only accept normalised answers
2. (Original post by EllaR97)
I was doing the Jun11 paper and the question asked "what is the smallest positive that can berepresented using normalised floating point system."
I put 0.0000001 with exponent of 1000, but the markscheme says 0.1000000 with exponent of 1000 - anyone know why?

Wikibooks agrees with me :-S

:-)
A normalised number has too start with 1.0 or 0.1, therefore although the number you are saying is smaller than the one the mark scheme is saying, your number isn't normalised
3. (Original post by StealthyNoodle4)
A Normalised floating point must have a 0(dot)1. It can't be a 0(dot)0.
(I maybe wrong, if so please correct me)
Ahhh yes, I remember that now! Thanks :-)
4. (Original post by EllaR97)
Ahhh yes, I remember that now! Thanks :-)
You're more than welcome! Good Luck for tomorrow!
5. Can anyone explain the operating system on phones. It was a question on the june 2014 paper. Good luck for tomorrow everybody XD x

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6. in case anyone needed the june 2014 paper...
Attached Images
7. AQA-COMP3-QP-Jun14.pdf (488.3 KB, 262 views)
8. (Original post by AnnieFraz)
Can anyone explain the operating system on phones. It was a question on the june 2014 paper. Good luck for tomorrow everybody XD x

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I think it's a case of remembering the points in the mark scheme, perhaps making some colourful flashcards to help you remember the points.

A phone OS may have a sandbox to run guest programs in.
A phone OS is likely to have less RAM/slower processor
Need to support certain set of peripherals like a GPS/gyroscope
Probably going to have sophisticated power management software
9. (Original post by EllaR97)
I was doing the Jun11 paper and the question asked "what is the smallest positive that can berepresented using normalised floating point system."
I put 0.0000001 with exponent of 1000, but the markscheme says 0.1000000 with exponent of 1000 - anyone know why?

Wikibooks agrees with me :-S

:-)
That's just what I put! It made sense in my head
10. June 2011 is a horrible paper!
11. How much do we have to know about how Turing machines work?
All i know is the basic definition of a Turing machine and a UTM.
12. (Original post by aLeXaNdRa08)
How much do we have to know about how Turing machines work?
All i know is the basic definition of a Turing machine and a UTM.
The majority of marks on Turing machines come from interpreting the logic of one, and writing out the movement and actions of the read and write head.

As far as definition and explanation questions go, you also need to know the significance of Turing machines to computing in general (both the standard ones and universal).

I have seen one other question regarding how a UTM can be likened to an interpreter.
13. (Original post by PythonGuy)
The majority of marks on Turing machines come from interpreting the logic of one, and writing out the movement and actions of the read and write head.

As far as definition and explanation questions go, you also need to know the significance of Turing machines to computing in general (both the standard ones and universal).

I have seen one other question regarding how a UTM can be likened to an interpreter.
Ok well thats good then. I'm just hoping that they don't suddenly chuck a six-mark question at us, about exactly how a Turing machine works.
14. Does anyone have a really neat way of remembering how to normalise a database into 3NF?
15. Are the get and post methods response or request?
16. Anyone know the Big O complexity of the insertion sort?
17. (Original post by TabbyGuy123)
Anyone know the Big O complexity of the insertion sort?
Big O is worst case, right? If so, it would be . Because the worst case would be if the list was the wrong way round, and each element had to compare to each element before (so n-1 + n-2 + n-3 + ... + 1), which would sum to .
18. What's a thick-client network please?
19. (Original post by AnnieFraz)
What's a thick-client network please?
In the context of the client-server model, a thick client has sufficient functionality to perform a lot of functions independent of the server whereas in contrast a thin client will rely on a server to perform most tasks.
20. (Original post by The Financier)
Does anyone have a really neat way of remembering how to normalise a database into 3NF?
Just remember 1st = Atomic Data, 2nd = No partial Dependancies, and 3rd = No Non key attributes!

Sort of in order of importance?
For 3NF there's also the court based rhyme of "Each attribute must represent a fact about the key, the whole key, and nothing but the key, so help me Codd!" (Codd was some database computer-y guy, you don't need to know anything about him for the exam but the rhyme might help!
21. (Original post by AlecRobertson)
That's just what I put! It made sense in my head
Normalised requires the radix to have different bits on either side

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