On the label of a hard drive you see CHS valuse. One of the valuses are the heads. The nummber can be either 16 or 255. What does this mean a drive has 255 heads when can only have a total of 8? Please help.

This was a physical geometry back in the days of MFM ST412/506 interface drives.

Now it is a translated value, a drive will not ordinarilly reveal it's actual position to a user. The value now is translated by the drive into an exact sector address, like an LBA. This is partly to make a modern drive work on a legacy BIOS addressing scheme, and partly because modern drives use a zoned sectoring scheme and do not have the same number of sectors per track on all tracks. The outer tracks have more sectors than the inner tracks do, in order to make more efficient use of the disk's surface area.

This is a good link, to understand that well its some advanced

http://www.ata-atapi.com/hiwchs.html


Regards