Get Drive Parameters
Entry:
AH - 48h
DL - Drive number
DS:SI - address of result buffer.
Exit:
carry clear
AH - 0
DS:SI - result buffer
carry set
AH - error code
Return physical device characteristics. This function is mandatory regardless of the interface subset which is supported.
Bit Description
0 DMA boundary errors are handled transparently
1 The geometry supplied in bytes 8-12 is valid
2 Device is removable
3 Device supports write with verify
4 Device has change line support (bit 2 must be set)
5 Device is lockable (bit 2 must be set).
6 Device geometry is set to maximum, no media is present (bit 2 must be set). This bit is turned off when media is present in a removable media device.
7-15 Reserved, must be 0
Result Buffer:
Offset Type Description
0 Word Buffer Size, must be 26 or greater. The
caller sets this value to the
maximum buffer size. If the length of this
buffer is less than 30, this
functions does not return the pointer to
the Enhanced Disk Drive structure (EDD).
If the Buffer Size is 30 or greater on
entry, it is set to exactly 30 on exit.
If the Buffer Size is between 26 and 29,
it is set to exactly 26 on exit. If the
Buffer Size is less than 26 on entry an
error is returned.
2 Word Information Flags In the following table, a 1 bit indicates that the feature is available, a 0 bit indicates the feature is not available and will operate in a manner consistent with the conventional Int 13h interface.
4 Double Word Number of physical cylinders. This is 1 greater than the maximum cylinder number. Use Int 13h Fn 08h to find the logical number of cylinders.
8 Double Word Number of physical heads. This is 1 greater than the maximum head number. Use Int 13h Fn 08h to find the logical number of heads.
12 Double Word Number of physical sectors per track. This number is the same as the maximum sector number because sector addresses are 1 based. Use Int 13h Fn 08h to find the logical number of sectors per track.
16 Quad Word Number of physical sectors. This is 1 greater than the maximum sector number.
24 Word Number of bytes in a sector.
26 Double Word Pointer to Enhanced Disk Drive (EDD) configuration parameters. This field is only present if Int 13h, Fn 41h, CX register bit 2 is enabled. This field points to a temporary buffer which the BIOS may re-use on subsequent Int 13h calls. A value of FFFFh:FFFFh in this field means that the pointer is invalid.
Get Drive Parameters
Entry:
AH - 48h
DL - Drive number
DS:SI - address of result buffer.
Exit:
carry clear
AH - 0
DS:SI - result buffer
carry set
AH - error code
Return physical device characteristics. This function is mandatory regardless of the interface subset which is supported.
Bit Description
0 DMA boundary errors are handled transparently
1 The geometry supplied in bytes 8-12 is valid
2 Device is removable
3 Device supports write with verify
4 Device has change line support (bit 2 must be set)
5 Device is lockable (bit 2 must be set).
6 Device geometry is set to maximum, no media is present (bit 2 must be set). This bit is turned off when media is present in a removable media device.
7-15 Reserved, must be 0
Result Buffer
Offset Type Description
0 Word Buffer Size, must be 26 or greater. The caller sets this value to the
maximum buffer size. If the length of this buffer is less than 30, this
functions does not return the pointer to the Enhanced Disk Drive
structure (EDD). If the Buffer Size is 30 or greater on entry, it is set to
exactly 30 on exit. If the Buffer Size is between 26 and 29, it is set to
exactly 26 on exit. If the Buffer Size is less than 26 on entry an error is
returned.
2 Word Information Flags In the following table, a 1 bit indicates that the feature
is available, a 0 bit indicates the feature is not available and will operate
in a manner consistent with the conventional Int 13h interface.
4 Double Word Number of physical cylinders. This is 1 greater than the maximum
cylinder number. Use Int 13h Fn 08h to find the logical number of
cylinders.
8 Double Word Number of physical heads. This is 1 greater than the maximum head
number. Use Int 13h Fn 08h to find the logical number of heads.
12 Double Word Number of physical sectors per track. This number is the same as the
maximum sector number because sector addresses are 1 based. Use Int
13h Fn 08h to find the logical number of sectors per track.
16 Quad Word Number of physical sectors. This is 1 greater than the maximum sector
number.
24 Word Number of bytes in a sector.
26 Double Word Pointer to Enhanced Disk Drive (EDD) configuration parameters. This
field is only present if Int 13h, Fn 41h, CX register bit 2 is enabled. This
field points to a temporary buffer which the BIOS may re-use on
subsequent Int 13h calls. A value of FFFFh:FFFFh in this field means
that the pointer is invalid.