Purpose

This function returns geometry and physical parameters about the specified physical hard disk, if available. This information is acquired from BIOS via INT 13h function 48h at system boot.

Parameter Packet Format

Field                            Length
Drive Number                     BYTE

Drive Number

The BIOS drive number for which geometry and physical parameters are requested. The value must be 80h or greater.

Data Packet Format

Field                                     LengthReserved                                  WORD
Information Flags                         WORD
Number of Physical Cylinders              DWORD
Number of Physical Heads                  DWORD
Number of Sectors Per Track               DWORD
Number of Physical Sectors                QWORD
Number of Bytes in a Sector               WORD
Reserved                                  DWORD
I/O Port Base Address                     WORD
Control Port Address                      WORD
Head Register Upper Nibble                BYTE
Reserved                                  BYTE
IRQ Information                           BYTE
Block Count for ATA R/W Multiple          BYTE
DMA Information                           BYTE
PIO Information                           BYTE
BIOS Selected Hardware Option Flags       WORD
Reserved                                  WORD
DPT Extension Revision                    BYTE

Information Flags

Bits are defined as follows

Bit

Description
0
DMA boundary errors are handled transparently
1
The geometry returned in bytes 4 15 is valid
2
Media is removable. Bits 4 6 are not valid if this bit is 0
3
Device supports write verify
4
Device has media change notification
5
Media is lockable
6
Device geometry is set to maximum and no media is present when this bit is set to 1.
7 15
Reserved
Number of Physical Cylinders
The number of physical cylinders on the physical drive. This field is valid only if BIT 1 of the information flags is set to 1.
Number of Physical Heads
The number of physical heads on the physical drive. This field is valid only if BIT 1 of the information flags is set to 1.
Number of Sectors Per Track
The number of sectors per track on the physical drive. This field is valid only if BIT 1 of the information flags is set to 1.
Number of Physical Sectors
The number of physical sectors on the physical drive.
Number of Bytes in a Sector
The number of bytes per sector on the physical drive.
I/O Port Base Address
This word is the address of the data register in ATA Command Block.
Control Port Address
This word is the address of the ATA Control Block Register.
Head Register Upper Nibble
The upper nibble of this byte is logically ORed with the head number, or upper 4 bits of the LBA, each time the disk is accessed.

Bit

Description
0 3
0
4
ATA DEV bit
5
1
6
LBA enabled (1 = enabled)
7
1
IRQ Information
Bits are defined as follows

Bit

Description
0 3
IRQ for this drive
4 7
0
Block Count for ATA R/W Multiple
If the hard disk was configured to use the READ/WRITE MULTIPLE command, then this field contains the block size of the transfer in sectors.
DMA Information
If the BIOS has configured the system to perform multi-word DMA transfers in place of the normal PIO transfers, this field specified the DMA mode in the upper nibble, as per the ATA-2 or later definition, and the DMA Channel in the lower nibble. ATA Channels which conform to SFF-8038i set the DMA channel to 0. Note that the DMA Type field does not follow the format of the data returned by the drive. The value of the DMA mode is not limited to 2.

Bit

Description
0 3
DMA Channel
4 7
DMA Type
PIO Information
If the BIOS has configured the system to perform PIO data transfers other than mode 0, this field specifies the PIO mode as per the ATA-2 or later definition.

Bit

Description
0 3
PIO Type
4 7
0
BIOS Selected Hardware Option Flags
Bits are defined as follows

Bit

Description
0
Fast PIO accessing enabled
1
DMA accessing enabled
2
ATA READ/WRITE MULTIPLE accessing enabled
3
CHS translation enabled
4
LBA translation enabled
5
Removeable media
6
ATAPI device
7
32 bit transfer mode
8
ATAPI device uses command packet interrupt
9 10
Translation type

00

Bit-shift translation
01
LBA assisted translation
10
Reserved
11
Vendor specific translation
11
Ultra DMA accessing enabled
12 15
Reserved
DPT Extension Revision
Revision of DPT Extension provided by BIOS

Returns

Possible values are shown in the following list

• NO_ERROR

  87

  ERROR_INVALID_PARAMETER

  Remarks

  Information in the data packet will be filled in, if BIOS supports INT 13h Function 48h and if BIOS can access the entire hardfile through INT 13h Function 42h and Function 43h. If either condition is not met, all fields in the data packet with be 0.

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