Hi Russ, Thank you for the clear explanation that you provided. I do have one comment/question to add to this. It was my understanding that the newer designs of hard disk have a relatively constant bit density on their tracks. The inner tracks would have fewer sectors than the outer ones. The firmware on board the hard drive electronics translates all the internal operations into whatever the external controller needs to see. Am I mistaken on this item? Peter ---------------------------------- [log in to unmask] -----Original Message----- To make it more complicated, the bit density varies between the inside and outside tracks of the platters, so that the measured speed depends on where the test was performed physically on the disk. Russ Poffenberger The NOSPIN Group is now offering Free PC Tech support at our newest website: http://freepctech.com