Int 13H [PC] [AT] [PS/2] Function 0CH (12) Seek

Positions the disk read/write heads to the specified cylinder, but does not transfer any data.

Call with:

AH = 0CH

CH = lower 8 bits of cylinder

CL = upper 2 bits of cylinder in bits 6—7

DH = head

DL = drive

80H—FFH fixed disk

Returns:

If function successful

Carry flag = clear

AH = 00H

If function unsuccessful

Carry flag = set

AH = status (see Int 13H Function 01H)

Notes:

This function is supported on fixed disks only.

The upper 2 bits of the 10-bit cylinder number are placed in the upper 2 bits of register CL.

The Read Sector, Read Sector Long, Write Sector, and Write Sector Long functions include an implied seek operation and need not be preceded by an explicit call to this function.