Western Digital T13/2132-D manual Get Device Parameters FN 48h, Result Buffer

T13/2132-D Revision 3 June 23, 2010

8.20 Get Device Parameters (FN 48h)

8.20.1 Overview

This function returns default device parameters. It shall be mandatory regardless of the interface subset that is supported. Table 22 defines the result buffer. On entry the first word of the result buffer shall be the buffer length in bytes.

Entry

AH 48h

DL BIOS device number

DS:SI Address of result buffer (see table 22)

Exit

Carry Clear Function completed without error

AH Shall be cleared to zero

DS:SI Address of result buffer (see table 22)

Carry Set Function completed with an error

AH Shall be set to the error code

			Table 22 — Result Buffer
Offset	Type		Description
0	Word	The caller shall set this value to the maximum Result Buffer length, in bytes. If the
		length of this buffer is less than 30 bytes, this function shall not return the pointer to
		Drive Parameter Table (DPT) extension. If the buffer length is 30 or greater on entry, it
		shall be set to 30 on exit. If the buffer length is between 26 and 29, it shall be set to 26
		on exit. If the buffer length is less than 26 on entry an error shall be returned.
2	Word	Information Flags. A value of one in a bit indicates that the feature shall be available. A
		value of zero in a bit indicates the feature shall be not available and shall operate in a
		manner consistent with the conventional INT 13h interface.
		Bit	Description
		15:8	Reserved
		7	BIOS calls INT13h FN 50h to access the device
		6	Device geometry shall be set to maximum and no media shall be present
			when this bit is set to one
		5	Media shall be lockable
		4	Device has media change notification
		3	Device supports write verify
		2	Media shall be removable. Bits 4-6 are not valid if this bit is cleared to zero
		1	The geometry returned in bytes 4-15 shall be valid
		0	DMA boundary errors are handled transparently
4	DWord	Number of default cylinders. The content of this field shall be one greater than the
		maximum cylinder number. INT 13h FN 08h shall be used to find the logical number of
		cylinders.
8	DWord	Number of default heads. The content of this field shall be one greater than the
		maximum head number. INT 13h FN 08h shall be used to find the logical number of
		heads.
12	DWord	Number of default sectors per track. The content of this field shall be the same as the
		maximum sector number because sector addresses are 1 based. INT 13h FN 08h shall
		be used to find the logical number of sectors per track.

48 Working Draft Enhanced Disk Drive - 4 (EDD-4)