Western Digital T13/2132-D 5 <8GB INT 13h Functions (Conventional Functions)

June 23, 2010 T13/2132-D Revision 3

Working Draft Enhanced Disk Drive - 4 (EDD-4) 13

5 <8GB INT 13h Functions (Conventional Functions)

The Conventional INT 13h functions can address a maximum of 8.4GB of device space. Sector sizes shall be

exactly 512 bytes. The Conventional INT 13h functions pass all parameters in registers using the following

template (see table 6) unless otherwise specified:

Table 6 — Conventional Register Definitions

AH INT 13h function number (Range is 00h through 3Fh)

AL Number of sectors to transfer

CH Low 8 bits of Cylinder

Bit Description

5:0 Sector number. This value shall be >= 01h and <= 3Fh

7:6 High order 2 bits of the cylinder

DH Head Number

Bit Description

6:0 Drive number

7 Set to 1 for Fixed media, clear to 0 for removable media

ES:BX This register contains the buffer pointer (i.e., the beginning address of the buffer in system memory).

Commands that move data from the device to memory shall use this pointer as the destination for

the data. Commands that move data from memory to the device shall use this pointer as the source

for the data to be transferred.