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INT 13h, 0Ch (12) Seek to Cylinder fixed disk
Positions the read/write heads over a specified cylinder for a fixed
disk. This service can be performed on fixed disks only.
On entry: AH 0Ch
CH Cylinder number (10-bit value; upper 2 bits
in CL)
DH Head number
DL Drive number (Bit 7 must be set)
Returns: AH Status of operation (See Service 01h)
CF Set if error, else cleared
--------------------------------------------------------------------------
Notes: The cylinder number is a ten-bit quantity (0 through
1023). Its most significant two bits are in bits 7
and 6 of CL; the remaining eight bits are in CH. The
starting sector number fits in the low-order portion
(lower 6 bits) of CL.
If an error is encountered, use Service 0h to reset
the drive and retry the operation.
Even though the head value is not needed, you must
supply a legal value--or else the seek will not be
performed and an error will be returned.
For the AT, XT-286, and PC Convertible, the BIOS
executes INT 15h, Service 90h (Device Busy), for the
diskette (Type = 01h) and the fixed disk (Type =
00h) prior to waiting for the interrupt. INT 15h,
Service 91h (Interrupt Complete), is executed upon
completion.