computer science gcse ocr

is this correct for magnetic storage:

data is stored magnetically as a bit which is stored in a small area called a sector within the circular tracks
the tracks are found on the surfaces of disks called platters
each sector represents one bit- if its magnetised then it represents binary 1 and if its demagnetised then it represents binary 0

also I don't really understand how particles are involved so any help would be greatly appreciated :smile:

Reply 1

Idra

We didn't study this in too much detail, but I believe each 'sector' is a slice of the disk that stores a set amount of bytes and 'tracks' refer to the rings that go around the disk. The attached image might help with this. Yes, the disk that has the data stored on it is called the 'platter' in hard drives. You're also correct in saying magnetised = 1 and demagnetised = 0. The read/write 'head' that moves over the disk can modify and read the magnetisation of the material directly under it. I'm not sure how particles are involved and can't find much information online though, are you sure this is on the syllabus?

images.jpg7.8KB

Reply 2

king1234567890

I do OCR CS and I don't think this is on the syalabus, but for extra context I would agree with the answer @idra gacw

Reply 3

grace10101

Original post by Idra

thanks so much for your help
I think the one thing thats confusing me is how the data is stored am I correct in saying the data is stored as a collection of bits or am I completely wrong.

Reply 4

grace10101

Original post by king1234567890

I do OCR CS and I don't think this is on the syalabus, but for extra context I would agree with the answer @idra gacw

Original post by grace10101

thanks so much for your help
I think the one thing thats confusing me is how the data is stored am I correct in saying the data is stored as a collection of bits or am I completely wrong.

I found the syllabus and I think you are right as it does say we aren't required to know about the components of each type of storage so thanks for pointing that out :smile:

(edited 3 years ago)

Reply 5

king1234567890

No problem. But I would recommend learning this because it will impress the examiner as not many people will learn it

Reply 6

grace10101

Original post by king1234567890

No problem. But I would recommend learning this because it will impress the examiner as not many people will learn it

thats a good point

Reply 7

Idra

Original post by grace10101

thanks so much for your help
I think the one thing thats confusing me is how the data is stored am I correct in saying the data is stored as a collection of bits or am I completely wrong.

Yup! So in most disks (hard drives specifically) each 'track sector' (refer to attached image) stores 512 bytes, and from what I've read then there is a map which shows which track sectors are full and which track sectors are empty called the 'File Allocation Table' or 'FAT' (credits to microsoft). When something needs to be written or found then the computer will refer to this map, move the head to where the data is stored and reads or writes from there.The thinking behind this is that anything on the disk can be navigated to and read quickly, whereas on punch-cards and stuff like that you can only read from start to end.