who can give me some theory about hard disk?

thanks very much!!

http://www.pcguide.com/ref/hdd/index.htm

I have this theory that hard drives are really tiny spacial-warp engines capable of transporting my data away from me! :p

Seriously, what do you mean by "hard drive theory"?

my english are really poor !but I try my best to learn!
I want to konw some theory about hard disk. For example the circuit of hard disk
and the elements of the head how to write and read on the disk

thanks for PrntRhd and saphalline

i supposed a lot of that information would be proprietary info that is "hush-hush"? eh i dunno, do some searching on the internet, maybe find an engineering forum. or, get some old items and tear them apart by hand...