Seagate STT8000A - Manual (Page 42)

Chapter 5 ATAPI Interface
Page 34 STT8000A Product Manual
information. If you do not program this register correctly, the drive "hangs" in the
BSY state. To correct this problem, reset operations.
Supported ATA Commands
The ATA commands are briefly described in the following paragraphs.
Execute Drive Diags (90h)
This command is executed regardless of the state of the DRV bit. The command
causes an actual microprocessor reset (drive loses all logical position information).
Power-up diagnostics are performed, and the PDIAG/DASP handshake is
performed per ATA-2 specification. The master device will generate an interrupt.
Idle Immediate (E1h)
This command causes the device to set its Power Mode state to Idle and to
generate an interrupt. Although the drive has no actual power saving features, this
command is emulated for software compatibility.
Standby Immediate (E0h)
This command causes the device to set its Power Mode state to Standby and to
generate an interrupt. Although the drive has no actual power saving features, this
command is emulated for software compatibility.
Check Power Mode (E5h)
This command causes the device to return its Power Mode state in the Int Reason
register, and generate an interrupt. If the drive is in Standby mode, this command
returns 00h in the Int Reason register, otherwise this command returns FFh in the
Int Reason register (indicating IDLE mode).
Previous Cmd Int Reason
Reset/Power-up FFh (Idle)
Standby Immed. 00h (Standby)
Idle Immediate FFh (Idle)
Any Other Cmd FFh (Idle)
Sleep (E6h)
This command is treated as an Idle command and does NOT prevent the drive from
responding to further commands.