Specifications

MICROPROCESSADORES
INTERRUPÇÕES
5
Luís Miguel Charrua Figueiredo 5 - 7 E.N.I.D.H.
CL = high bits of cylinder number (bits 7,6)
DH = head
DL = drive
Return
: CF set on error
CF clear if successful
AH = status code (see #00234)
Notes
: AWARD AT BIOS and AMI 386sx BIOS have been extended to
handle more than 1024 cylinders by placing bits 10 and 11 of the cylinder number
into bits 6 and 7 of DH for XT-type controllers on an AT or higher, AH=0Fh should
be called first the IBM AT BIOS and many other BIOSes use only the low four bits
of DH (head number) since the WD-1003 controller which is the standard AT
controller (and the controller that IDE emulates) only supports 16 heads not all
controller support sector types 20h and 40h under Windows95, an application
must issue a physical volume lock on the drive via INT 21/AX=440Dh before it can
successfully write to the disk with this function
SeeAlso
:
AH=05h"FLOPPY",AH=06h"FIXED",AH=07h"FIXED",AH=0Fh,AH=18h,AH=1Ah
INT 13 - FIXED DISK - FORMAT TRACK AND SET BAD SECTOR FLAGS
(XT,PORT)
AH = 06h
AL = interleave value
CH = cylinder number (bits 8,9 in high bits of CL)
CL = sector number
DH = head
DL = drive
Return
: AH = status code (see #00234)
Note
: AWARD AT BIOS and AMI 386sx BIOS have been extended to
handle more
than 1024 cylinders by placing bits 10 and 11 of the cylinder number
into bits 6 and 7 of DH
SeeAlso
: AH=05h"FIXED",AH=07h"FIXED"
INT 13 - FIXED DISK - FORMAT DRIVE STARTING AT GIVEN TRACK
(XT,PORT)
AH = 07h
AL = interleave value (XT only)
ES:BX = 512-byte format buffer (see AH=05h)
CH = cylinder number (bits 8,9 in high bits of CL)
CL = sector number
DH = head
DL = drive
Return
: AH = status code (see #00234)
Note
: AWARD AT BIOS and AMI 386sx BIOS have been extended to
handle more than 1024 cylinders by placing bits 10 and 11 of the cylinder number
into bits 6 and 7 of DH
SeeAlso
: AH=05h"FIXED",AH=06h"FIXED",AH=1Ah
INT 13 - DISK - GET DRIVE PARAMETERS (PC,XT286,CONV,PS,ESDI,SCSI)
AH = 08h
DL = drive (bit 7 set for hard disk)
ES:DI = 0000h:0000h to guard against BIOS bugs
Return
: CF set on error
AH = status (07h) (see #00234)
CF clear if successful
AH = 00h
AL = 00h on at least some BIOSes
BL = drive type (AT/PS2 floppies only) (see #00242)
CH = low eight bits of maximum cylinder number
CL = maximum sector number (bits 5-0)
high two bits of maximum cylinder number (bits 7-6)
DH = maximum head number
DL = number of drives
ES:DI -> drive parameter table (floppies only)
Notes
: may return successful even though specified drive is greater than the
number of attached drives of that type (floppy/hard); check DL to ensure validity
for systems predating the IBM AT, this call is only valid for hard disks, as it is
implemented by the hard disk BIOS rather than the ROM BIOS the IBM ROM-
BIOS returns the total number of hard disks attached to the system regardless of
whether DL >= 80h on entry. Toshiba laptops with HardRAM return DL=02h when
called with DL=80h, but fail on DL=81h. The BIOS data at 40h:75h correctly
reports 01h. may indicate only two drives present even if more are attached; to
ensure a correct count, one can use AH=15h to scan through possible drives
Reportedly some Compaq BIOSes with more than one hard disk controller return
only the number of drives DL attached to the corresponding controller as specified
by the DL value on entry. However, on Compaq machines with "COMPAQ"
signature at F000h:FFEAh, MS-DOS/PC DOS IO.SYS/IBMBIO.COM call INT
15/AX=E400h and INT 15/AX=E480h to enable Compaq "mode 2" before
retrieving the count of hard disks installed in the system (DL) from this function.
the maximum cylinder number reported in CX is usually two less than the total
cylinder count reported in the fixed disk parameter table (see INT 41h,INT 46h)
because early hard disks used the last cylinder for testing purposes; however, on
some Zenith machines, the maximum cylinder number reportedly is three less than
the count in the fixed disk parameter table. for BIOSes which reserve the last
cylinder for testing purposes, the cylinder count is automatically decremented on
PS/1s with IBM ROM DOS 4, nonexistent drives return CF clear, BX=CX=0000h,
and ES:DI = 0000h:0000h machines with lost CMOS memory may return invalid
data for floppy drives. In this situation CF is cleared, but AX,BX,CX,DX,DH,DI, and
ES contain only 0. At least under some circumstances, MS-DOS/PC DOS
IO.SYS/IBMBIO.COM just assumes a 360 KB floppy if it sees CH to be zero for a
floppy. The PC-Tools PCFORMAT program requires that AL=00h before it will
proceed with the formatting if this function fails, an alternative way to retrieve the
number of floppy drives installed in the system is to call INT 11h. In fact, the MS-
DOS/PC-DOS IO.SYS/IBMBIO.COM attempts to get the number of floppy drives
installed from INT 13/AH=08h, when INT 11h AX bit 0 indicates there are no floppy
drives installed. In addition to testing the CF flag, it only trusts the result when the
number of sectors (CL preset to zero) is non-zero after the call.
BUGS
: several different Compaq BIOSes incorrectly report high-numbered
drives (such as 90h, B0h, D0h, and F0h) as present, giving them the same
geometry as drive 80h; as a workaround, scan through disk numbers, stopping as
soon as the number of valid drives encountered equals the value in 0040h:0075h
a bug in Leading Edge 8088 BIOS 3.10 causes the DI,SI,BP,DS, and ES registers
to be destroyed some Toshiba BIOSes (at least before 1995, maybe some
laptops??? with 1.44 MB floppies) have a bug where they do not set the ES:DI
vector even for floppy drives. Hence these registers should be preset with zero
before the call and checked to be non-zero on return before using them. Also it
seems these BIOSes can return wrong info in BL and CX, as S/DOS 1.0 can be
configured to preset these registers as for an 1.44 MB floppy. The PS/2 Model 30
fails to reset the bus after INT 13/AH=08h and INT 13/AH=15h. A workaround is to
monitor for these functions and perform a transparent INT 13/AH=01h status read
afterwards. This will reset the bus. The MS-DOS 6.0 IO.SYS takes care of this by
installing a special INT 13h interceptor for this purpose. AD-DOS may leave
interrupts disabled on return from this function. Some Microsoft software explicitly
sets STI after return.
SeeAlso
: AH=06h"Adaptec",AH=13h"SyQuest",AH=48h,AH=15h,INT 1E
SeeAlso
: INT 41"HARD DISK 0"
(Table 00242)
Values for diskette drive type:
01h 360K
02h 1.2M
03h 720K
04h 1.44M
05h ??? (reportedly an obscure drive type shipped on some IBM
machines)
2.88M on some machines (at least AMI 486 BIOS)
06h 2.88M
10h ATAPI Removable Media Device
INT 13 - HARD DISK - INITIALIZE CONTROLLER WITH DRIVE PARAMETERS
(AT,PS)
AH = 09h
DL = drive (80h for first, 81h for second)
Return
: CF clear if successful
CF set on error
AH = status (see #00234)
Notes
: on the PC and XT, this function uses the parameter table pointed at
by INT 41 on the AT and later, this function uses the parameter table pointed at by
INT 41 if DL=80h, and the parameter table pointed at by INT 46 if DL=81h
SeeAlso
: INT 41"HARD DISK 0",INT 46"HARD DISK 1"