Hardware Reference
In-Depth Information
By reversing this formula, you can convert the other way—that is, from LBA back to
CHS:
For these formulas, the abbreviations are defined as follows:
LBA = Logical block address
Using these formulas, you can calculate the LBA for any given CHS address, and vice
versa. Given a drive of 16,383 cylinders, 16 heads, and 63 sectors per track,
Table 7.16
shows the equivalent CHS and LBA addresses.
Table 7.16 Equivalent CHS and LBA Sector Numbers for a Drive with 16,383 Cylinders, 16 Heads,
and 63 Sectors per Track (16,514,064 Sectors Total)
BIOS Commands Versus ATA Commands
In addition to the two methods of sector addressing (CHS or LBA), there are two levels
of interface where sector addressing occurs. One interface is where the operating system
talks to the BIOS (using driver commands); the other is where the BIOS talks to the drive
