Chapter 5

ATAPI Interface

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.

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STT8000A Product Manual

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Seagate STT8000A manual Supported ATA Commands, Previous Cmd Int Reason