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Copyright 1991 David Jurgens |
INT 13,C - Seek to Cylinder (XT & newer)
AH = 0C
CH = low order byte of cylinder number (see below)
CL = high order byte of cylinder number (see below)
DH = head number (0-15)
DL = fixed drive number (80h=drive 0, 81h=drive 1)
on return:
AH = status (see INT 13,STATUS)
CF = 0 if successful
= 1 if error
- many good programming references indicate this function is only
available on the AT, PS/2 and later systems, but all hard disk
systems since the XT have this function available
- notice that CX is in reverse byte format similar to the way data
is stored in memory and reverse of normal register storage
- only the disk number is checked for validity
- the parameters in CX change depending on the number of cylinders;
the track/cylinder number is a 10 bit value taken from the 2 high
order bits of CL and the 8 bits in CH (low order 8 bits of track):
│F│E│D│C│B│A│9│8│7│6│5-0│ CX
│ │ │ │ │ │ │ │ │ │ └───── unused
│ │ │ │ │ │ │ │ └─┴─────── high order 2 bits of track number
└─┴─┴─┴─┴─┴─┴─┴────────── low order 8 bits of track number
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| Esc or Alt-X to exit |
int 13,c |
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