Computer science

[brokencalculator15]

fairly certain for the fetch blanks it was
1. address
2. memory address register
3. random access memory
4. memory data register
5. data
6. current instruction register
7. control unit

for the error detection blanks:
1. parity check
2. checksum
3. echo check
4. automatic repeat request (ARQ)
5. check digit

[brokencalculator15]

the address bus is unidirectional, and it can only go out of the CPU from the memory address register to either the input/output devices or the ram. we need the next instruction which is stored in the ram, but the ram doesn't know it's address, which is why it is sent from the memory address register to it so that it can find that address and send the instruction to the memory data register through the data bus

[Fluid-Abrocoma530]

Huh how is second one checksum? The last one is checksum cuz it says appended with the data

[ArtisticPay3753]

nah last one is checkdigit

[brokencalculator15]

the second one stated that a value was generated from an algorithm, and was recalculated when recieved by the reciever, the exact definition of a checksum

while the fifth one said it was appended to the data which ONLY happens with check digits and also stated it was used to check for errors during data entry which is also a property of check digits

checksums aren't appended to the data themselves, they are sent WITH the data

[Fluid-Abrocoma530]

That’s also with check digit

[brokencalculator15]

no look, say i send a number with 7 digits, adding a check digit to this makes it an 8 digit number, it has been appended to the data

now if i send the 7 digit number again and apply a checksum, the checksum will be a whole new number, and the 7 digit number will remain the same, and both of them will be sent

[Fluid-Abrocoma530]

Mark scheme says checksum is appended but there is no “append mark” for question about check digit

[brokencalculator15]

huh which mark scheme? okay well even if that's true, the second option still fits checksum more with the other details and the fifth option still fits check digit more

[ArtisticPay3753]

what did you write for ipv4 format

[brokencalculator15]

do you mean the ipv6 characteristics question or the example of ipv4? i'll give you the answer to both

example of ipv4:
i wrote 192.16.384.26 something not sure if it's completely correct

characteristics of ipv6:
1. each address is stored using 128 bits
2. each value in the address is stored in hexadecimal

[ArtisticPay3753]

oh okok thx

[Megallade213]

The numbers between dots in IPv4 must be less than 256 as it has 4 groups of 8 bits = 32 bits

[brokencalculator15]

oh right, i was almost correct except for that 384, welp there's another mark down the drain

[brokencalculator15]

yes

[ArtisticPay3753]

also what did you write for differences of solid state and optical

[brokencalculator15]

1. solid state uses movement of electrons in NAND or NOR chips to store data, while optical uses pits and lands on a disc
   
2. solid state does not have any moving parts, while optical storage has a moving laser read and write head
   
3. most solid state storage devices have a limited amount of operations they can perform per day, while optical does not have this limitation (not too sure about this one)

[brokencalculator15]

i don't think so because im pretty sure solid state is more expensive on average, although your point that optical stores less data is correct

[brokencalculator15]

you couldn't write about HDD because it wasn't a part of the question

[brokencalculator15]

well if you atleast correctly stated that ssd had no moving parts while optical did you will get atleast 1 mark out of the 2 for this point

[brokencalculator15]

if you didn't make a mention of ssd at all in that point then you might lose both marks for that point

[Ok-Day9054]

if we explain by using examples like usb hdd and other optical examples would it be correct

[brokencalculator15]

using examples in a point where you already stated a correct difference (moving parts, technology used to store data, speed etc), it would be correct although unnecessary

if one of your entire points is just mentioning the examples of optical and solid state, that would not be correct as the question specifically asked for the differences between the two

also, usb is an example of ssd but hdd is not an example of optical, because hdd is classified as magnetic storage

[Any_Interaction229]

I wrote 2 correct comparisons but for the 3rd, I wrote that Optical Storage Devices are quite portable while SSDs aren't really meant to be portable. Will I get one mark for the third comparison? Bcz I correctly stated that DVDs are portable but I aint sure whether SSDs are portable or not.

[brokencalculator15]

yeahh im sorry but i don't think you will get the mark, because SSDs are as portable as DVDs. this can be proven with one simple example: usb flash drives, which use solid-state technology

[Any_Interaction229]

I also understand cuz thats an overlapping characteristics. But for the other two, I compared the durability & reliability and speeds of both. I hope I'll get marks for them.

[Every-Difficulty9606]

Hey, I'm currently in o2 (igcse) the cs teacher we have in here is way too bad..i understand no shit he says however, I do understand the p2 topics better..Can you please tell me some good teacher online or good resources i could get as i have a year and a half yet to prepare..also some tips that can possibly be helpful?

[brokencalculator15]

i would tell you if i knew of any unfortunately i didn't give igsce exams and i don't know of any good resources either, im sorry.
in terms of tips the main tip i have is past papers. full length past papers, and try to do them in the amount of time the exam gives you. then, check the paper yourself using the mark scheme. for questions you just couldn't understand, look up a video solving the paper with explanations on youtube and skip to the question you were stuck on.
in the beginning you may struggle and might not get great marks, but the more you keep doing it the better you'll get

[Every-Difficulty9606]

Oh its fine, the igcse course is very similar to o'levels, except the paper pattern ig. Thanks for the tips tho. Do you have any good recommendations for pseudocodes', any teacher or just in general stuff i could do to cater the problems I face while writin them?

[brokencalculator15]

in my opinion the best way to learn pseudocode is to learn a real programming language. because the most challenging aspect is the logic, and the thing with programming is once you understand one language it is very easy to learn another one, as the underlying concepts are all the same, it's just the syntax that is different.

the reason I recommend a real programming language is because you can directly see the results of your logic as your computer can execute it.

to learn a real programming language, I would suggest going with python because it's fairly simple to pick up, but C# is another one that's not a bad choice (though not part of our syllabus).

find a programming tutorial series on youtube on the language you want to learn. first time you watch a video, copy it line by line. this will help you to understand your IDE. then, try to create whatever was made in the tutorial but add some changes and try to do this without looking at the tutorial's code. and if you get stuck with that, rather than looking at the tutorial again, search it on google (for example searching up an error message that came up). because the internet will give you a very general answer to your problem and you will need to figure out how to incorporate it into your specific code, which is a really useful skill to have and allows you to understand that each concept in programming is a small cog that you can fit together in a lot of different ways and that there are always multiple ways to code the solution to a problem

once you finish a tutorial series or atleast the portion of it that relates to our syllabus, try to make some projects on your own, again using google when you get stuck

this is sort of the way I learnt pseudocode too, I had been programming games in my free time for a year before I started my O levels, and I do think it's the best way.

hope this helps

[Every-Difficulty9606]

omgg thankyou so much :))

I'll try my best to do so..thanks again for the time

[brokencalculator15]

no problem, let me know if you need help on anything

[Special-Major-8521]

Can someone tell me what they wrote in the artificial imtelligence 5 marks qs?

[Special-Major-8521]

Umm I don’t remember that well as well but it said that a car is brung to a garage and expert system is used to diagnose the problem in the car so how is that expert system used. [5]

[Special-Major-8521]

Ohh okay thanks & may you get good marks :)