AQA COMP2 7th June 2011 AM

Original post by sr135

I always like to simply using tables.

For example, if it is simplify Q = A + A . NOT B. I would do the following:

Q = A + A . NOT B
Let X = A
Let Y = A . NOT B

Therefore, Q = X + Y

A          B          X          Y          Q
0          0          0          0          0
0          1          0          0          0
1          0          1          1          1
1          1          1          0          1

So there we have the table of results for Q.

We can then conclude that Q is only 1 when A is 1 and that is it.

So Q = A + A . NOT B = A

Make sense to you? There is DeMorgan's laws etc. but I don't know them and find this way easier.

I just like to break it up. You could even break it up into X, Y and Z if you like.

Yeah, but surely they could ask it either way, or in fact I guess they ask it in a why you can use either solution, if they say you MUST use the laws or trace table then that's harsh.

Anyway the rules are:
1. Simplification = Get rid of multiple subjects (A+A+A is always going to be A...)
2. Commutative = Change the order of anything outside of the brackets (A+B+B+A may be easier to read/work with if you change it to A+A+B+B)
3. Associate = if the signs inside and outside of the brackets are the same (i.e. all .'s or all +'s) you can remove the brackets
4. Distributive = if the signs are idfferent then multiply out (apply the character(s) outside the brackets to everything inside the brackets individually)
5. De-Morgan's = Not everything, not each indivudal subject then change the sign (converts AND's to OR's and OR's to AND's)

Reply 82

Original post by Lc8_66

Still kinda confused but with the h1 example, all h1's would be blue? Cos that make sense, if not then i'm confused.

Yes all h1's would be blue.

Reply 83

Student21

8

My head is now experiencing a meltdown. I've been revising all day for like 2 weeks now. I have to ace this exam to have the slightest chance of entering uni. Our teacher did not make it any easier by teaching us 1/4 of the syllabus for COMP3.

Reply 84

Original post by Lc8_66

Yeah, but surely they could ask it either way, or in fact I guess they ask it in a why you can use either solution, if they say you MUST use the laws or trace table then that's harsh.

Anyway the rules are:
1. Simplification = Get rid of multiple subjects (A+A+A is always going to be A...)
2. Commutative = Change the order of anything outside of the brackets (A+B+B+A may be easier to read/work with if you change it to A+A+B+B)
3. Associate = if the signs inside and outside of the brackets are the same (i.e. all .'s or all +'s) you can remove the brackets
4. Distributive = if the signs are idfferent then multiply out (apply the character(s) outside the brackets to everything inside the brackets individually)
5. De-Morgan's = Not everything, not each indivudal subject then change the sign (converts AND's to OR's and OR's to AND's)

Not seen a question yet where it tells you what method to use. Your rules above are good :smile:

Reply 85

Sadly, still confused with the selectors and HTML as a whole.

Can you use multiple ID selectors if the actual selector is different? So you can only have one winner but you can have a winner and a runner up? so #Winner and #RunnerUp

Because all notes are contradicting, I have no clue. Surely if you had #winner{ color: red} and you had two winners (like a winner later on as well) you would want them both in red and not have to call them winner1 and winner2 because winner2 replaces winner1 but winner1 was still the winner when it was first shown.

Reply 86

Original post by Lc8_66

Sadly, still confused with the selectors and HTML as a whole.

Can you use multiple ID selectors if the actual selector is different? So you can only have one winner but you can have a winner and a runner up? so #Winner and #RunnerUp

Because all notes are contradicting, I have no clue. Surely if you had #winner{ color: red} and you had two winners (like a winner later on as well) you would want them both in red and not have to call them winner1 and winner2 because winner2 replaces winner1 but winner1 was still the winner when it was first shown.

Id selectors separate sections of the web page. So for winners like you described classes would be used because a class can be used by any element and can be used multiple times within a web page

And ID selector can only be used once in the webpage. Its used for things like header or footer etc

So if you have a specific style for your header ONLY, then use the ID selector

Reply 87

Original post by Lc8_66

Sadly, still confused with the selectors and HTML as a whole.

Can you use multiple ID selectors if the actual selector is different? So you can only have one winner but you can have a winner and a runner up? so #Winner and #RunnerUp

Because all notes are contradicting, I have no clue. Surely if you had #winner{ color: red} and you had two winners (like a winner later on as well) you would want them both in red and not have to call them winner1 and winner2 because winner2 replaces winner1 but winner1 was still the winner when it was first shown.

You can have multiple ID and class selectors. ID's are only really meant to be used once and class's more often. ID's are more for groups of objects and text wherease class's are more for bits of text/paragraphs/images etc.

You would have:

.winner {color: red}
<p class="winner">text1</p>
<p class="winner">text2</p>
<p class="winner">text3</p>
<p class="winner">text4</p>

or:

#winner {color: red}
<div id="winner">
<p>text1</p>
<p>text2</p>
<p>text3</p>
<p>text4</p>
</div>

Notice the # and . in the above examples and class= and id=.

ID's can be used more than once and it works but they are not designed to be.

Reply 88

Original post by Dobby28

Id selectors separate sections of the web page. So for winners like you described classes would be used because a class can be used by any element and can be used multiple times within a web page

And ID selector can only be used once in the webpage. Its used for things like header or footer etc

So if you have a specific style for your header ONLY, then use the ID selector

thought that :smile:

but u can have more than one ID selector but a different name? so a winner and a runner up? as you only have 1 of each and are only used once each.

Reply 89

Original post by Lc8_66

thought that :smile:

but u can have more than one ID selector but a different name? so a winner and a runner up? as you only have 1 of each and are only used once each.

Yep you definitely can. Just like you can have IDs for header and footer and other things, you can also make some for winners and runners up :smile:

Reply 90

Anyone else staying up most of the night for this exam? Iv spent all day going over the topics and now just got the hardware topic left andthen im guna do past papers; very last minute i know. Wish it was an afternoon exam!

Reply 91

Original post by fluteflute

Thing is the textbook isn't that great for hardware devices. They asked about laser v. inkjet in one paper - the book's information of inkjets is practically non existant :P

Im going to do past papers soon but what iv revised from the book there are differnces mentioned between the differemt printers

Reply 92

Good Luck everyone :smile:

Reply 93

How did people find it? We can talk about it right because it is AQA?

Reply 94

Jiten88

It had some easy questions but a fair few of them where very specific, so you either knew it or didn't.

Reply 95

Original post by sr135

How did people find it? We can talk about it right because it is AQA?

I think so. Anyway it was pretty difficult, the first question even stumped me when it was SOOOOOOOOOOOOOOO OBVIOUS my mind just went blank and afterwards when I looked at my notes I was like "OMFG, you idiot!" I messed up COMP 1's 'easy' questions and now with COMP 2 as well.

One (especially one) of the questions on the Data Protection Act was silly, it broke 2 principles and it asks to give the only principle it broke. Also where was the 4-8 marker on the hardware device...It was 1 mark on the difference between a DVD and CD...

How about you?

(edited 12 years ago)

Reply 96

examstressed

Original post by sr135

How did people find it? We can talk about it right because it is AQA?

it was alrite wat boxes did u tick for da 1st question??

Reply 97

Moogled

TICK
____TICK
________TICK
those are the boxes i tick!!

(edited 12 years ago)

Reply 98

Student21

8

Original post by Moogled

TICK
____TICK
________TICK
those are the boxes i tick!!

I ticked Special Purpose for both Payroll and Flight control.

Anywayz what did you log get on the boolean algebra question?

(edited 12 years ago)

Reply 99