hard disk

Point value changed by question poster.

See the following sites
HowStuffWorks - How Hard Disks Work
http://howstuffworks.com/hard-disk.htm

www.zdnet.com/products/storageuser/harddisk.htm

www.pcguide.com/ref/hdd/index -c.html

There should be no spaces in the URL

Hi,

Conceptually a hard disk is little more than a metal oxide covered record or platter (if you remember record players!) where the "needle" is actually a sensor reading magnetic spots on the disk.

There are some fundamental differences, though.
A record has one track - a spiral, whereas a hard disk has many many concentric circular tracks and consequently needs to move the needle in and out itself. It doesn't follow a groove.

A hard disk spins very fast. Usually either 5,400 times per minute or 7,200 times per minute.

As it spins, the magnetic spots on the platter move beneath that sensor and a moving magnetic spot going past metal causes a little bit of electricity to flow in that metal.

The magnetic spots on the platterare either magnetised in one direction or the other (like the opposing ends of a magnet). Lets call them 0 and 1.

So the information read at a particular spot is either a 0 or a 1. If you read 8 consecutive spots, then you have what is called a "byte".

It might look like this...

00110101

That is actually a binary number! I wont go into binary, but suffice to say that is the binary representation of the decimal number fifty three.

Computers are based on these binary representations of numbers and so thats how they store this information long term.

Of course real hard drives are far more complex in the way they operate, but at the end of the day, after all the efficiency improvements, thats all they do...

Cheers,
Tim.

This question was auto closed due to inactivity