Chapter
6
I
BIOS
Services
Exit Conditions:
See “Exits From All Calls” below.
AL
=
number of sectors verified
Format
on
Floppy
Disk
Format the desired track.
Entry Conditions:
AH
=
5
DL
=
drive number (0-1)
DH
=
had
number (0-1)
CH
=
track number
(0-39)
CL
=
sector number
(1
-9)
ES:BX
5
pointer to
a
group of address fields for each track.
Each
address field is made up
of
4 bytes. These are C,
H,
R,
and N, where:
C
=
track number
H
=
head number
R
=
sector number
N
=
the number of bytes per sector (00
=
128, 01
=
There is one entry for every sector on a given track.
256,02
=
512,03
=
1024)
E
xi
t
Conditions
:
See “Exits From All Calls” below.
Exits
From All
Calls:
AH
=
Status
of
operation, where set
=
true:
Error Code Condition
01H Illegal Function
02H Address Mark Not Found
03H Write Protect Error
04H Sector Not Found
08H DMA Overrun
09H
10H
20H Controller Failure
40H Seek Failure
80H
[NC]
=
operation successful (AH
=
0)
[C]
=
operation failed (AH
=
error status)
Attempt
To
DMA Across A 64K Boundary
Bad CRC on Disk Read
Device Timeout, Device Failed To Respond
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