How does the index of a disk work in finding the desired address? I've been trying to understand computer concepts and such recently and I've been curious to know how the process works of a processor asking for an address and sending the bits to the hard drive, as well as how the hard drive index works when it's just a bunch of magnetic specs that cooperate with a mechanical arm. What does the index say to the system? How do the processor and HDD cooperate? Hopefully I'm asking on the right website this time due to the fact that I accidentally posted this question on the Computational Science site. Thanks

-Ryan
The index specifies the cylinder, head, and sector where the data resides.  The hard drive then moves the arm/head so it is positioned over that block and reads the data stored in that block as the disk rotates under the arm.  The hard drive then sends that data back to the processor.   Read http://pages.cs.wisc.edu/~remzi/OSTEP/file-disks.pdf for more of an overview how hard drives work.