GCSE computer science 17th may exam
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An iterative loop uses variables - which contains values as a parameter; take the variable for example and iterate through X to the variable i.e X = 10 [FOR i in X (do this) else terminate. It is quite simple once you think about it as the program just looks at every value and compares its value using the parameter. Make you understand that iteration is NOT the same as sequencing
No... They are not called "algorithms" it is simply programming. An algorithm by its very meaning is a set of instructions with specific functions. Whereas programming is used as being generic.
It is like comparing a variable to a value... They are NOT the same.
Paper 2 is literally algorithm based questions. It also includes binary addition, and binary/denary/hex conversions. There's a select few other things too. Everything you just listed is in paper 1.
You missed out 7 other topics... Arrays, Table handling, Validation santilisation, SQL, Logic...
Is it? check the specification...
http://filestore.aqa.org.uk/resources/computing/specifications/AQA-8520-SP-2016.PDF
Sos, can't get a link... it says chapters 3-7 are paper 2.... it does have the conversions though. But Algorithms is chapter 1.... but I think they will probably include a couple algorithm questions because you need assumed knowledge of the first few chapters in it too.
http://filestore.aqa.org.uk/resources/computing/specifications/AQA-8520-SP-2016.PDF
Sos, can't get a link... it says chapters 3-7 are paper 2.... it does have the conversions though. But Algorithms is chapter 1.... but I think they will probably include a couple algorithm questions because you need assumed knowledge of the first few chapters in it too.
I think they're talking about OCR because that's how it's set out for that board.
I also said "there's a few other things too". I don't have that good of a memory. Plus, the topics I mentioned are the main ones in the papers that I've taken, hence I remember them. I was just using them as an example, considering he listed the *wrong* ones.
I'd be surprised if some of those even come up in any detail. Logic only shows up in the form of one true/false table at the end.
http://filestore.aqa.org.uk/resources/computing/specifications/AQA-8520-SP-2016.PDF
Sos, can't get a link... it says chapters 3-7 are paper 2.... it does have the conversions though. But Algorithms is chapter 1.... but I think they will probably include a couple algorithm questions because you need assumed knowledge of the first few chapters in it too.
Thats a 2016 one but paper 1 was a lot of "theory" but what im revising is algorithms, Programming techniques, Producing Robus programs, Computational logic, Translators and Data representations (which is hexadecimal parts), Btw thats aqa
http://filestore.aqa.org.uk/resources/computing/specifications/AQA-8520-SP-2016.PDF
I take OCR papers. Is there an AQA paper 2 tomorrow as well?
I'd be surprised if some of those even come up in any detail. Logic only shows up in the form of one true/false table at the end.
Yes hopefully but sometimes exam boards can be the contrary and add a few things that will catch people out.
I hope not lol! SQL and table handling is easy atleast.
A loop always compries of at least two things:
•
One or more instructions (the "body" of the loop) - i.e. the instructions which are executed at each pass or iteration
•
A conditional expression - i.e. a boolean expression which evaluates to true or false at each pass or iteration. The conditional expression decides whether the computer will 'break out' of the loop, or whether there will be another iteration.
Just to illustrate the concept, while loop is possibly the simplest to understand - e.g.
WHILE ( Something is true )
Do instructions
END WHILE
•
The first thing a 'while' loop does is evaluate its expression for true or false.
•
In nearly all loops, the expression involves a variable whose value could change inside the loop body.
•
If the expression is true, it executes the body of the loop through a single pass.
•
When the loop has finished, the expression is evaluated again for true or false.
•
If the expression is still true, it executes the body of the loop through another single pass
•
When the loop has finished, the expression is evaluated again for true or false.
•
This keeps repeating until the expression finally evaluates to false - the program will 'break out' of the loop and carry on with the rest of the program.
Another way to express the while loop above would look like this:
LABEL "start"
IF ( Something is false )
GOTO LABEL "end"
ELSE
Do instructions
GOTO LABEL "start"
LABEL "end"
In a real programming language, a compiler would do something very similar to this. If you've studied CPU architecture, you might be familiar with a CPU register known as the Program Counter. The program counter keeps track of which line the CPU is going to execute next. CPUs have a "GOTO" instruction which allows a program to override the Program Counter. (Sometimes "GOTO" is known as "JUMP" or "BRANCH" - it's all the same thing though)
Compilers translate a while loop into machine code using "Goto" instructions to allow the CPU to keep repeating the same code - so when a while loop evaluates its condition as false, the CPU sees a GOTO instruction which move the program counter past the end of the loop to prevent it from being executed.
So that's how loops work in programming. Pseudocode is the same - you just need to imagine that there's a program counter somewhere, and remember that the loop is just modifying the program counter..
An iterative loop uses variables - which contains values as a parameter; take the variable for example and iterate through X to the variable i.e X = 10 [FOR i in X (do this) else terminate. It is quite simple once you think about it as the program just looks at every value and compares its value using the parameter. Make you understand that iteration is NOT the same as sequencing
Thank you so much!
A loop always compries of at least two things:
•
One or more instructions (the "body" of the loop) - i.e. the instructions which are executed at each pass or iteration
•
A conditional expression - i.e. a boolean expression which evaluates to true or false at each pass or iteration. The conditional expression decides whether the computer will 'break out' of the loop, or whether there will be another iteration.
Just to illustrate the concept, while loop is possibly the simplest to understand - e.g.
WHILE ( Something is true )
Do instructions
END WHILE
•
The first thing a 'while' loop does is evaluate its expression for true or false.
•
In nearly all loops, the expression involves a variable whose value could change inside the loop body.
•
If the expression is true, it executes the body of the loop through a single pass.
•
When the loop has finished, the expression is evaluated again for true or false.
•
If the expression is still true, it executes the body of the loop through another single pass
•
When the loop has finished, the expression is evaluated again for true or false.
•
This keeps repeating until the expression finally evaluates to false - the program will 'break out' of the loop and carry on with the rest of the program.
Another way to express the while loop above would look like this:
LABEL "start"
IF ( Something is false )
GOTO LABEL "end"
ELSE
Do instructions
GOTO LABEL "start"
LABEL "end"
In a real programming language, a compiler would do something very similar to this. If you've studied CPU architecture, you might be familiar with a CPU register known as the Program Counter. The program counter keeps track of which line the CPU is going to execute next. CPUs have a "GOTO" instruction which allows a program to override the Program Counter. (Sometimes "GOTO" is known as "JUMP" or "BRANCH" - it's all the same thing though)Programming languages use a "Goto" statement in machine code to allow the CPU to keep repeating the same code - so when a while loop evaluates its condition as false, it uses a GOTO statement to move the program counter past the end of the loop to prevent it from being executed. So that's how loops work in programming. Pseudocode is the same - you just need to imagine that there's a program counter somewhere, and remember that the loop is just modifying the program counter..
SO but everything you said said contains **** we don't need...
A loop always compries of at least two things:
•
One or more instructions (the "body" of the loop) - i.e. the instructions which are executed at each pass or iteration
•
A conditional expression - i.e. a boolean expression which evaluates to true or false at each pass or iteration. The conditional expression decides whether the computer will 'break out' of the loop, or whether there will be another iteration.
Just to illustrate the concept, while loop is possibly the simplest to understand - e.g.
WHILE ( Something is true )
Do instructions
END WHILE
•
The first thing a 'while' loop does is evaluate its expression for true or false.
•
In nearly all loops, the expression involves a variable whose value could change inside the loop body.
•
If the expression is true, it executes the body of the loop through a single pass.
•
When the loop has finished, the expression is evaluated again for true or false.
•
If the expression is still true, it executes the body of the loop through another single pass
•
When the loop has finished, the expression is evaluated again for true or false.
•
This keeps repeating until the expression finally evaluates to false - the program will 'break out' of the loop and carry on with the rest of the program.
Another way to express the while loop above would look like this:
LABEL "start"
IF ( Something is false )
GOTO LABEL "end"
ELSE
Do instructions
GOTO LABEL "start"
LABEL "end"
In a real programming language, a compiler would do something very similar to this. If you've studied CPU architecture, you might be familiar with a CPU register known as the Program Counter. The program counter keeps track of which line the CPU is going to execute next. CPUs have a "GOTO" instruction which allows a program to override the Program Counter. (Sometimes "GOTO" is known as "JUMP" or "BRANCH" - it's all the same thing though)
Compilers translate a while loop into machine code using "Goto" instructions to allow the CPU to keep repeating the same code - so when a while loop evaluates its condition as false, the CPU sees a GOTO instruction which move the program counter past the end of the loop to prevent it from being executed.
So that's how loops work in programming. Pseudocode is the same - you just need to imagine that there's a program counter somewhere, and remember that the loop is just modifying the program counter..
OMG Thank you so much this was a really good explaination and i feel like understand it so much better now!!
Oh, it's OCR? That makes sense...
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