How do I compute the capacity of a hard disk?

I have a worked example of how to compute the capacity of a hard disk, could anyone explain where the BOLD figures came out of?

RPM: 7200

no of sectors: 400

no of platters: 6

no of heads: 12

cylinders: 17000

avg seek time: 10millisecs

time to move between adj cylinders: 1millisec

the first line of the answer given to me is:

12 x 17 x 4 x 512 x 10^5

I just want to know where the parts in bold came from.The 512 I dont know. The 10 is from the seek time but its power 5?

From stackoverflow

• The answer is

  heads x cylinder x sectors x 512 (typical size of one sector in bytes)
  

  so this is

  12 x 17000 x 400 x 512
  

  which is the same as

  12 x 17 x 1000 x 4 x 100 x 512
  

  and

  100 = 10^2
  1000 = 10^3
  10^2 x 10^3 = 10^5
  

  As you want the capacity, you don't need any times here.

  A reference for the 512 bytes can be found at Wikipedia, for example (and it also has a similar example with the same formula a bit below).

  BlueRaja - Danny Pflughoeft : beat me to it :)

  schnaader : Was pretty lucky that I saw the question almost as it appeared - I'll wait a bit on the next one so you can take it ;)

  Andrew : +1 with caveat, I think heads should really be the platters x 2 - although normally you would expect 1 head per side of a platter it isn't guarenteed.

  schnaader : See the Wikpedia link: "Naturally, a platter has 2 sides and thus 2 surfaces on which data could be manipulated; usually there are 2 heads per platter--one on each side, but not always." So I guess we can assume that and as the number of heads is given, I chose to use that one.

  schnaader : But of course you're right that it's still an assumption, as well as the sector size of 512 bytes which will perhaps change to 4096 bytes in the near future.