OCR A-level Computer Science Paper 1 (H446/01) - 12th June 2023 [Exam Chat]

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Is this incorrect? I thought it should be 1.11 for the first step. If not, would appreciate if someone explained why it is how it is as shown in the picture

Reply 81

sdosf

Original post by genghiskhan2

Is this incorrect? I thought it should be 1.11 for the first step. If not, would appreciate if someone explained why it is how it is as shown in the picture

I agree with you
to make a TC binary number negative, you 'flip the bits and add 1':
so 0.01 (0.25) becomes 1.10, add 1 to give 1.11, as you suggested.
Then to normalise it we need it in the form 10 or 01 for negative and positive number respectively
we move the . two places to the right, so the exponent is going to be -2, which is 1110
final answer: 1.000 1110
(-1 x 2^(-2) = -0.25)

Reply 82

sdosf

Original post by mokord

What if the mantissa started with 0 should you fill the front with two zeros instead?

Yes. This is due to how two's compliment works
Let's take the 4 bit number 1110, which is -2 in denary
If we add a zero to the front, this will change the value to 01110, converting it from -2 to 14!
..That's why we add 1s to the front. Because 11110 still equals -2, and so does 11111111111110!
If a TC binary number begins with 0, it means that it is are positive. e.g. 0010 = 2
So adding as many 0s to the front will keep it as 2: 00000010 = 2, 010 = 2 etc.

TL;DR: yes, fill in with 0s if the most significant bit is 0, and 1s if it is 1
hopefully that is clear and helpful, if it isn't lmk and i can explain further :smile:

Reply 83

sdosf

Original post by helluzaa

can anyone give me a list of topics that might come up on this

https://www.physicsandmathstutor.com/computer-science-revision/a-level-ocr/
Everything on the 3rd column from the left - A-Level Computer Systems 1.x

Reply 84

sdosf

Original post by anon5648

hey what info that may or may not end up being useful can you throw at me about OOP

After an OOP programming question they tend to just ask things like 'using an example from the code above, define encapsulation/polymorphism/inheritance'
It is worth learning these concepts as well as how to code OOP as tbh all coding questions are easy marks (5/6 marks for defining a class)
Though you are leaving it very late, it could come up in P2 though

Reply 85

swnap

if theres any floating point questions then ill just skip, its not worth the mental strain :biggrin:

my teacher didnt teach this so im going off yt videos. annnd each video says something different sooo

Reply 86

Ngngngngng

just hoping, boolean algebra doesnt come up. ill litreally cry if it does.

Reply 87

kelrasheed

What grade do you guys think you’ll realistically get? I think if I get 90 on this paper I should be on track for an A since Paper 2 is easier

(edited 10 months ago)

Reply 88

morningfork

Original post by kelrasheed

What grade do you guys think you’ll realistically get? I think if I get 90 on this paper I should be on track for an A since Paper 2 is easier

is paper 2 meant to be easier? help

Reply 89

Ngngngngng

Original post by kelrasheed

What grade do you guys think you’ll realistically get? I think if I get 90 on this paper I should be on track for an A since Paper 2 is easier

i would be lucky if i get above 50

Reply 90

Kingemperor07

Yeah

Original post by morningfork

is paper 2 meant to be easier? help

Reply 91

sdosf

Original post by swnap

if theres any floating point questions then ill just skip, its not worth the mental strain :biggrin:

my teacher didnt teach this so im going off yt videos. annnd each video says something different sooo

I guess it's too late to start learning FP now but definitely worth giving it a go in the exam

Reply 92

swnap

i find paper 1 easier

Original post by morningfork

is paper 2 meant to be easier? help

Reply 93

yourlocalness

someone just drop the exam paper in the chat that would be funny :biggrin:

(im failing)

Reply 94

swnap

Original post by sdosf

I guess it's too late to start learning FP now but definitely worth giving it a go in the exam

always glad to lower the boundaries for everyone

Reply 95

Ngngngngng

Original post by swnap

always glad to lower the boundaries for everyone

+1, real sacrifice!!

Reply 96

kelrasheed

Original post by swnap

i find paper 1 easier

Paper 1 has like 10 mark lower grade boundaries cause it’s just a memory test and I cba to memorise all that (as with most)

Reply 97

swnap

exactly. im good at remembering things but if i have to work something out... which is why ive failed physics...

Original post by kelrasheed

Paper 1 has like 10 mark lower grade boundaries cause it’s just a memory test and I cba to memorise all that (as with most)

Good luck guys!

well that went awfully lmao

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OCR A-level Computer Science Paper 1 (H446/01) - 12th June 2023 [Exam Chat]

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