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T13/2132-D Revision 3 June 23, 2010
16 Working Draft Enhanced Disk Drive - 4 (EDD-4)
Table 9 — Device Address Packet
Offset Type Description
0 Byte Packet size in bytes. The value in this field shall be 16 (10h) or greater. If the packet size
is less than 16 the request shall be rejected with CF = 1b and AH = 01h.
1 Byte Reserved.
2 Byte Number of blocks to transfer. This field shall contain a maximum value of 127 (7Fh). If
this field is set to FFh, then the transfer buffer address shall be found at offset 10h, the
number of blocks to transfer shall be found at offset 18h, and the transfer buffer at offset 4
shall be ignored. If this field is set to 00h, then no data shall be transferred. If any other
value is supplied, then the request shall be rejected with CF=1b and AH=01h
3 Byte Reserved.
4 DWord Address of host transfer buffer. This is the host buffer that Read/Write operations shall
use to transfer the data. This is a 32-bit host address of the form Seg:Offset. If this field
is set to FFFFh:FFFFh then the address of the transfer buffer shall be found at offset 10h.
8 QWord Starting logical block address on the target device of the data to be transferred. This is a
64-bit unsigned linear address. If the device supports LBA addressing this value should
be passed unmodified. If the device does not support LBA addressing the routine making
the INT 13h call shall convert this LBA to a CHS address using the current geometry in
the following formula:
LBA = (C
1
* H
0
+ H
1
) * S
0
+ S
1
= 1
Where:
C
1
= Selected Cylinder Number
H
0
= Number of Heads (Maximum Head Number + 1)
H
1
= Selected Head Number
S
0
= Maximum Sector Number
S
1
= Selected Sector Number
For ATA compatible devices with less than or equal to 15,482,880 logical sectors, the H
0
and S
0
values are supplied by words 3 and 6 of the data returned as a result of an
IDENTIFY DEVICE command.
10h QWord 64-bit unsigned linear address of the host transfer buffer. This is the host buffer that
Read/Write operations shall use to transfer the data if the data at offset 4 is set to
FFFFh:FFFFh, or the data at offset 2 is set to FFh.
18h DWord Total number of blocks to transfer when the data at offset 2 is set to FFh
1Ch DWord Reserved.
Note 1 - The options described in table 1 allow a host to use a 7-bit transfer size with a 32 -bit or 64-bit
memory address for the transfer buffer. Table 1 also allows a 32-bit transfer size in conjunction with
a 64-bit address. A 32-bit transfer size shall not be used in conjunction with a 32-bit memory
address.