AQA A2 COMP 3 Computing 2015 - Official Thread

Reply 300

Gigabit

14

What do we actually have to know about hashing?

Reply 301

username1050473

14

We have something like 4 A2 classes, so that's about 60-70... and I think there's three A2s who are female. It's very concerning and there should be a push to make more women feel comfortable taking STEM subjects :tongue:

Reply 302

helloinvader

2

Original post by AlecRobertson

What do we actually have to know about hashing?

This link is quite good
http://filestore.aqa.org.uk/subjects/AQA-2510-W-TRB-COMP3HASH.PDF

Reply 303

Darth_Bane

1

Original post by helloinvader

This link is quite good
http://filestore.aqa.org.uk/subjects/AQA-2510-W-TRB-COMP3HASH.PDF

Ahh, f**k hashing! My teacher didn't even teach us it all, she literally gave us this and told us just to read it and we were expected to understand it!! :angry:

Reply 304

Async

19

Original post by Darth_Bane

Ahh, f**k hashing! My teacher didn't even teach us it all, she literally gave us this and told us just to read it and we were expected to understand it!! :angry:

Read this
https://en.wikibooks.org/wiki/A-level_Computing/AQA/Problem_Solving,_Programming,_Operating_Systems,_Databases_and_Networking/Programming_Concepts/Hashing

It makes it so easy to understand

Then use,

https://www.youtube.com/watch?v=yoMOAIzBSpY

to consolidate

It helped me so much. Good luck!

(edited 8 years ago)

Reply 305

Darth_Bane

1

Original post by Async

Read this
https://en.wikibooks.org/wiki/A-level_Computing/AQA/Problem_Solving,_Programming,_Operating_Systems,_Databases_and_Networking/Programming_Concepts/Hashing

It makes it so easy to understand

Then use,

https://www.youtube.com/watch?v=yoMOAIzBSpY

to consolidate

It helped me so much. Good luck!

Cool thanks, appreciate it! :smile:

I've actually seen the first video, but that was before I knew about hashing

Reply 306

HamLetuceTomato

I think it is gonna be hard to tell what's going to show up, considering this spec has only been used for 5 years. I guess the sensible thing is to assume that what hasn't shown up so far is likely to appear. Those are my thoughts anyway!

Reply 307

Async

19

Original post by HamLetuceTomato

I think it is gonna be hard to tell what's going to show up, considering this spec has only been used for 5 years. I guess the sensible thing is to assume that what hasn't shown up so far is likely to appear. Those are my thoughts anyway!

Not just that but AQA are incredibly skilled at screwing students over. Don't be surprised if you see a wild question in the exam.

Reply 308

mb_12

1

Hi, found this earlier...

AQA COMP 3 - Key Notes.pdf882.5KB

Reply 309

ScruffyQuaver

9

Original post by mb_12

Hi, found this earlier...

Wow this is very helpful, thanks

Reply 310

username1200599

12

Original post by sarcasmrules

We have something like 4 A2 classes, so that's about 60-70... and I think there's three A2s who are female. It's very concerning and there should be a push to make more women feel comfortable taking STEM subjects :tongue:

There is a push lol. Cyber industry is making a huge fuss

Reply 311

Gigabit

14

Can somebody tell me the third normal form saying, something like, '...the whole key and nothing but the key...', but there's more?

Reply 312

StealthyNoodle4

Original post by AlecRobertson

Can somebody tell me the third normal form saying, something like, '...the whole key and nothing but the key...', but there's more?

Every attribute is dependent on the key, the whole key and nothing but the key.
I think that's what gets you the marks in the exam.

Reply 313

Gigabit

14

Thanks a lot buddy!

I need like 115 UMS for an A so I'm a little bit ****ed!

Reply 314

StealthyNoodle4

No worries! Good luck for tomorrow, I'm sure you'll do fine! :smile:

Reply 315

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

Thanks in advance!
:-)

Reply 316

StealthyNoodle4

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

Thanks in advance!
:-)

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)

Reply 317

PythonGuy

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

Thanks in advance!
:-)

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

Reply 318

Computing7788

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

Thanks in advance!
:-)

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