Ata Registers; Status Register - Seagate STT20000A Product Manual

Chapter 5

ATA registers

Status Register

Page 32
The following table lists the values for the registers during register initialization.
Register POR
STATUS 00h
ERROR 01h
(No
Error)
Sector Count 01h
(ATAPI Intr.
Reason)
Sector 01h
Number
(ATAPI
Reserved)
Cylinder Low 14h
(ATAPI Byte
Count High)
Cylinder High EBh
(ATAPI Byte
Count High)
Drive/Head 00
During an ATA soft reset or aborted ATA command, the host view of the DSC bit (Status
register) will be cleared, along with the DRDY bit. Any ATAPI command including ATAPI
Identify) can be used to set DRDY true and to re-enable host view of DSC bit.
The following layout represents the Status Register. The CORR and IDX bits are not
used by the drive.
7 6
BSY DRDY
(0)
Bit Mnemonic
7 BSY
6 DRDY
4 DSC
3 DRQ
0 CHECK
RESET– ATA Reset
(Hard Reset) (SRST Bit)
00h 00h
01h 01h
01h 01h
01h 01h
14h 14h
EBh EBh
00 00
5 4 3
- DSC DRQ
Description
Busy—set when only drive has access to ATA registers.
Drive Ready—set when DSC is valid.
Drive Seek Complete—set when drive ready for command.
Data Request—set when data ready to be transferred.
Check—set when an error has occurred.
ATAPI Interface
ATAPI Soft Read/Identify
Reset Device Cmds
10h 41h
(DRDY+ERR)
01h 04h
(ABRT)
01h —
01h —
14h 14h
EBh EBh
— —
2 1
CORR IDX CHECK
(0) (0)
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