Int 13/AH=25h

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HARD DISK - PS/1 and newer PS/2 - IDENTIFY DRIVE

AH = 25h
DL = drive number (80h,81h)
ES:BX-> 512 byte buffer for reply packet

Return:
CF clear if successful CF set on error AH = status (see #00234 at AH=01h) buffer filled with ATA/IDE-style drive information block (see #00267)

Desc: Retrieves the 256 words of drive data stored on an IDE hard disk

Notes: The byte at address 0040h:0074h is set to the status of the operation. IBM officially classifies this function as optional

See Also: AH=23h"PS/1"

Format of drive information block: Offset Size Description (Table 00267) 00h WORD general drive configuration (see #00268) 02h WORD number of cylinders 04h WORD reserved 06h WORD number of heads 08h WORD number of unformatted bytes per track 0Ah WORD number of unformatted bytes per sector 0Ch WORD number of sectors per track 0Eh 6 BYTEs vendor unique 14h 20 BYTEs serial number in ASCII, 0000h=not specified) 28h WORD buffer type 2Ah WORD buffer size in 512 byte increments (0000h=not specified) 2Ch WORD number of ECC bytes passed on Read/Write Long cmds 0000h = not specified 2Eh 8 BYTEs firmware revision in ASCII, 0000h=not specified 36h 40 BYTEs model number in ASCII, 0000h=not specified 5Eh WORD bits 15-8 Vendor Unique bits 7-0 00h = Read/Write Multiple commands not implemented xxh = Maximum number of sectors that can be transferred per interrupt on Read and Write Multiple commands 60h WORD 0000h = cannot perform doubleword I/O 0001h = can perform doubleword I/O 62h WORD capabilities bit 15-9 0=reserved bit 8 1=DMA Supported bit 7-0 Vendor Unique 64h WORD reserved 66h WORD bits 15-8 PIO data transfer cycle timing mode bits 7-0 Vendor Unique 68h WORD bits 15-8 DMA data transfer cycle timing mode bits 7-0 Vendor Unique 6Ah WORD bits 15-1 reserved bit 0 1=the fields reported in tranlation mode are valid 0=the fields reported in translation mode may be valid 6Ch WORD number of current cylinders 6Eh WORD number of current heads 70h WORD number of current sectors per track 72h DWORD current capacity in sectors 76h WORD reserved 78h 136 BYTEs not defined by ATA spec 2.6 100h 64 BYTEs vendor unique 140h 96 BYTEs reserved

Note: The above description is as in the ATA (AT Attachment) Specification.

See Also: #P0516

Bitfields for general drive configuration: Bit(s) Description (Table 00268) 15 0 reserved for non-magnetic drives 14 format speed tolerance gap required 13 track offset option available 12 data strobe offset option available 11 rotational speed tolerance is > 0.5% 10 disk transfer rate > 10 Mbs 9 disk transfer rate > 5Mbs but <= 10Mbs 8 disk transfer rate <= 5Mbs 7 removable cartridge drive 6 fixed drive 5 spindle motor control option implemented 4 head switch time > 15 usec 3 not MFM encoded 2 soft sectored 1 hard sectored 0 reserved (0)

Category: Disk I/O Enhancements - Int 13h - H

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