Hard Disk Drive Parameter Table

Offset Description
00h-01h Number of cylinders
02h Number of heads
03h-04h reserved
05h-06h Write-precompensation cylinder
07h reserved
08h Control byte
Bits 7-6 Enable retries
00b enable
01b disable
10b disable
11b disable
Bit 5 1b defect map located at last cylinder + 1
Bit 4 0b reserved
Bit 3 0b up to 8 heads
1b more than 8 heads
Bits-0 000b reserved
09h-0Bh reserved
0Ch-0Dh Landing zone (park cylinder)
0Eh Number of sectors per track
0Fh reserved