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back2root:ibm-pc-ms-dos:interrupts:int_13:int_13_08
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INT 0x13 - 0x08 - Get Current Drive Parameters (XT & newer)
The 1983 version of the “IBM XT BIOS Technical Reference” shows these functions are available for the XT but many other programming references say they aren't available until the AT.
This is probably due to misunderstanding the design of the disk BIOS. Upon bootup the hard disk BIOS replaces the default INT 13h diskette handler with the hard disk INT 13h handler.
Request/Call
| reg | value | descr |
|---|---|---|
| AH | 0x08 | |
| DL | var | Drive number (0=A, 1=2nd floppy, 0x80=drive 0, 0x81=drive 1) |
| 0x_ |
Return
| reg | descr |
|---|---|
| CF | 0 if successful 1 if error |
| AH | status (see INT 13,01) |
| BL | CMOS drive type 01 - 51/4: 360K 02 - 51/4: 1.2Mb 03 - 31/2: 720K 04 - 31/2: 1.44Mb |
| CH | cylinders (0-1023 dec. see below) |
| CL | sectors per track (see below) |
| DH | number of sides (0 based) |
| DL | number of drives attached |
| ES:DI | pointer to 11 byte Disk Base Table (DBT) |
Notes & Comments
- 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)
- 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
- only the disk number is checked for validity
| bit | descr |
|---|---|
| 0-5 | sector number |
| 6-7 | high order 2 bits of track/cylinder |
| 8-15 | low order 8 bits of track/cyl number |
back2root/ibm-pc-ms-dos/interrupts/int_13/int_13_08.txt · Dernière modification : de frater
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