# Computing Exam HelpWatch

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#1
can some1 explain how exactly index addressing works. I've got cpt4 (AQA) exam tomorrow... and still not quite sure of a good defenition of index addressing...
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#2
anyone sitting cpt4 tomorrow?
0
16 years ago
#3
(Original post by maljosh)
anyone sitting cpt4 tomorrow?
yeah i am. i was dreading it but when i looked at what u need to get an A i thought it cant be that bad.

The operand should be added to the value in the index register to find the address in Main Memory of the data to be operated on.

Hope this helps!
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#4
thanks for the defenition mate. How about an example?

January 2003 paper

Q8 part 4

At the moment 121 is in accumulator...and you have these locations:

120 1
121 2
122 3
123 4
124 5
125 6

and the answer is 127.. i don't get it?
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#5
oh i got it...

i forgot about the register (index register was X=5), so it's 121+5(X)+1(address in main memory)=127

Thanks a lot mate,
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16 years ago
#6
(Original post by maljosh)
thanks for the defenition mate. How about an example?

January 2003 paper

Q8 part 4

At the moment 121 is in accumulator...and you have these locations:

120 1
121 2
122 3
123 4
124 5
125 6

and the answer is 127.. i don't get it?

Sorry Mate. I tried doing that question yesterday and i got it wrong. For some reason i got 123.

N E ways i figure its definately worth knowing the definition as its likely to pop in the exams.

Good luck tomoz!
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#7
good luck to you too,

I have a bad feeling we gonna get a horrid recursive algorithm,
0
16 years ago
#8
Lol I took this exam exactly a year ago and can remember soooo little about it. In my mind it is just the harder programming paper. Cant believe I got an A for that paper.
0
16 years ago
#9
Yeah I got this exam tomorrow...trouble is my lecturer knows jack-all so I have had to learn the entire module in a just a short while on my own
0
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