COMP3 - JUN 2016 Discussion Thread

Is it just me or are grade boundaries really high for this paper, considering that they aren't particularly easy and that the markschemes aren't very forgiving either? :L

How quickly do most of you finish? I reckon I'll have an hour to stare at questions I don't know how to answer

The grade boundaries for this are so ****ed lol.
Is anyone else in my position?
I need 58 on comp 3 for B grade
80 for A grade
86 for A*

I NEVER got this.

How can you figure out the largest/smallest positive and negative number for a number with a specific amount of bits??

You could memorise them or figure it out in the exam (probably can't remember them now...)

Largest Positive
First of all know that the mantissa must be positive (so the first bit in the mantissa is a 0). The mantissa may as well then be as big as you can possibly get it to be as it will all add up in the end, so the rest will be 1's

You will also want the exponent to be as big as possible (not negative!) so the first bit will be 0 followed by all 1's

Lowest Negative
The mantissa will be negative as the number you are looking for is negative, so the first bit is a 1

Any subsequent 1's in the mantissa will actually make the mantissa smaller (as -1 + 1/2 = -1/2...) so you will want the rest of the mantissa set to 0's

Smallest positive (non zero)
You want mantissa to be positive, so the first bit is a 0

You'll want the mantissa to be as small as possible (but still positive) so the rest should be 0's except the last bit in the mantissa as that will create the smallest positive mantissa you can get

The exponent will only make it bigger unless it is negative, so set the first bit to 1 and then the rest will be 0 because any 1's following it will actually make the exponent higher (and therefore you'll get a higher number)

Smallest Negative (closest to 0 but not 0)
What do you think?

Yeah man, after my AS results I need to average 65% this year for an A, which is what I need for uni... Shouldn't be too hard in theory but a lot of my exams so far have stepped up a bit difficulty-wise, so praying the same won't be true for COMP3 D:

And on a side note has anyone done the specimen paper? wtf its hard

How can you tell if a floating number is not normalised?

Normalised = no leading zeroes.

So no more than 1 zero at the start for the sign?

Could somebody quickly make a quick summary of subnet masks and Subnet IDs? I'm pretty sure I get it, but I want to be certain, thanks.

Subnet mask identifies which computers are on the same segment
Subnet mask does an AND operation with the student's computer IP address
Subnet mask does an AND operation with the web server's ip address / destination ip address
Result of AND operation is the network ID
Network IDs compared
If the networks id dont match computers arent on same segment

network id/ subnet id i think theyre the same and this was worth 6 points