6. ATA Command Specification
Packet
SONY AIT-2 Turbo drive SDX-560V series Ver.1.0
6-20
Register
7 6 5 4 3 2 1 0
Error
na
Interrupt reason
(Sector Count)
Reserved (00h)
REL
I/O
C/D
Sector Number
na
Byte count low
(Cylinder Low)
Byte count (7-0)
Byte count high
(Cylinder High)
Byte count (15-8)
Device/Head
1 na 1 DEV na na na na
Status
BSY DRDY DF DSC DRQ na na CHK
Byte count high/low registers -
These registers reflect the value set by the host when the command was issued.
Interrupt reason register -
REL is cleared to zero.
I/O is cleared to zero indicating transfer to the device.
C/D is set to one indicating the transfer of a command packet.
Device/Head register -
DEV indicates the selected device.
Status register -
BSY is cleared to zero.
DRDY is na
DF is cleared to zero.
DSC is set to one.
DRQ is set to one.
CHK is cleared to zero.
Data transmission
When the Sony ATAPI Drive is ready to transfer data requested by a data transfer command, the Sony ATAPI
Drive sets the following register content to initiate the data transfer.
Register
7 6 5 4 3 2 1 0
Error
00h
Interrupt reason
(Sector Count)
Reserved (00h)
REL
I/O
C/D
Sector Number
na
Byte count low
(Cylinder Low)
Byte count (7-0)
Byte count high
(Cylinder High)
Byte count (15-8)
Device/Head
1 na 1 DEV na na na na
Status
BSY DRDY DF DSC DRQ na na CHK
Byte count high/low registers -
If the transfer is to be in PIO mode, the byte count of the data to be transferred for this DRQ assertion is
presented.
Valid byte count values are as follows:
a) the byte count is less than or equal to the byte count limit value from the host;
b) the byte count is not zero;
c) the byte count is less than or equal to FFFEh;
d) the byte count is even except for the last transfer of a command;
e) if the byte count is odd, the last valid byte transferred is on DD [7-0] and the data on DD [15-8]
is a pad byte of undefined value;
f) if the last transfer of a command has a pad byte, the byte count shall be odd.
