AS AQA Computer Science 2016 Revision Help

DibbyDabby

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Does anyone know of any good revision sites for this course ?

I'm struggling to find any resources.

Also if you have any questions or need any help feel free to ask

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Polapod

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I just came here to ask the same thing, I can't find anything useful online and the textbooks at college aren't much help either so I have no idea how to revise

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GarlicBread01

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Im in exactly the same position!!

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Someboady

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err.. OCR... and exactly the same position

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GarlicBread01

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Hey guys I was revising encryption and on the spec it says

So I now what Caeser cipher is, but im not sure why it is easily cracked?

Could anyone help?

Thanks

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DibbyDabby

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(Original post by GarlicBread01)
Hey guys I was revising encryption and on the spec it says

So I now what Caeser cipher is, but im not sure why it is easily cracked?

Could anyone help?

Thanks

I am not sure but i would say because there are only 26 different caesar ciphers (26 letters of the alphabet). It is fairly easy to crack using brute force by trying each of the 26 keys and seeing which one works.

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Hōseki

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(Original post by Someboady)
err.. OCR... and exactly the same position

Check out craigndave.

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MaxWillis99

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Which part of the Course are you struggling to find resources for? Coding or the Theory?

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peterxz

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(Original post by GarlicBread01)
Hey guys I was revising encryption and on the spec it says

So I now what Caeser cipher is, but im not sure why it is easily cracked?

Could anyone help?

Thanks

It's easily cracked because the pattern is incredibly easy to spot, as each letter is shifted +-X characters.

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GarlicBread01

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(Original post by MaxWillis99)
Which part of the Course are you struggling to find resources for? Coding or the Theory?

Theory mainly, coding theres actually pretty good amount of resources to practise and learn

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Someboady

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(Original post by GarlicBread01)
Theory mainly, coding theres actually pretty good amount of resources to practise and learn

Where can I find these resources? By coding you mean writing algorithms/pseudocode, not a specific language right?

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GarlicBread01

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(Original post by Someboady)
Where can I find these resources? By coding you mean writing algorithms/pseudocode, not a specific language right?

Sorry I mean websites where you can practise to program a specific language :/ like codeacademy.com

A-Level Computer Science in general is scarce on any good videos, notes or revision guides which is such a shame

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bakersman110

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(Original post by GarlicBread01)
Theory mainly, coding theres actually pretty good amount of resources to practise and learn

we haven't got long left, im struggling with the coding side

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GarlicBread01

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Hi guys, I was reading through the AQA A Level Computer Science (new) specifcation and in section 3.9.1.2 "Communication Basics" it says

Spoiler:

Show

But I was wondering, the additional information next to baud rate says
"Bit rate can be higher than baud rate if more than one bit is encoded in each signal change"

Should it not be the other way around? Since (according to my book) baud rate usually has 1 signal change per second, but it is possible to encode multiple signal changes in one second and then baud rate can potentially surpass bit rate.

Isn't it then suppose to say "Baud rate can be higher than bit rate if more than one bit is encoded in each signal change."

Im confused?

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username1357713

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(Original post by GarlicBread01)
Hi guys, I was reading through the AQA A Level Computer Science (new) specifcation and in section 3.9.1.2 "Communication Basics" it says

Spoiler:

Show

But I was wondering, the additional information next to baud rate says
"Bit rate can be higher than baud rate if more than one bit is encoded in each signal change"

Should it not be the other way around? Since (according to my book) baud rate usually has 1 signal change per second, but it is possible to encode multiple signal changes in one second and then baud rate can potentially surpass bit rate.

Isn't it then suppose to say "Baud rate can be higher than bit rate if more than one bit is encoded in each signal change."

Im confused?

Bit rate is the number of bits that can be sent per second
Baud rate is the number of signal changes per second

If one bit (a 1 or a 0) is sent per signal then the bit rate and the baud rate are equal. If more than one bit is sent per signal then more bits are being sent each second than the number of signal changes, hence the bit rate would be higher than the baud rate.

Increasing the baud rate would increase the bit rate, having more signals means sending more bits. Baud rate cannot be higher than the bit rate.

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GarlicBread01

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(Original post by CheetahCurtis)
Bit rate is the number of bits that can be sent per second
Baud rate is the number of signal changes per second

If one bit (a 1 or a 0) is sent per signal then the bit rate and the baud rate are equal. If more than one bit is sent per signal then more bits are being sent each second than the number of signal changes, hence the bit rate would be higher than the baud rate.

Increasing the baud rate would increase the bit rate, having more signals means sending more bits. Baud rate cannot be higher than the bit rate.

Oh wow thanks so much for clearing that up, it makes at lot more sense now!

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User1452521

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Has anyone got the full pre-liminary material? All I've received is the skeleton code and was jus wondering if anyone has receive extra for Sections A and B for PAPER 1

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sagederby

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(Original post by brodingoson)
Has anyone got the full pre-liminary material? All I've received is the skeleton code and was jus wondering if anyone has receive extra for Sections A and B for PAPER 1

Extra what?
The only preliminary material produced is the stuff about the skeleton program.
If the exam is like the specimen paper then section A will have some theory questions and an algorithm to convert into code. Section B will have questions about the skeleton program that will not require any coding.
To get an idea of the type of questions asked for section B and the algorithms, you should have a look at the Comp1 papers on the AQA web site.

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sagederby

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(Original post by DibbyDabby)
Does anyone know of any good revision sites for this course ?

I'm struggling to find any resources.

Also if you have any questions or need any help feel free to ask

Try this.
https://en.m.wikibooks.org/wiki/A-level_Computing/AQA

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VivianaC

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Does anyone know where to find additional practice exercises for the Monster Program in Java? Apart from those that AQA have released...

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