Test Unit Ready (00) - IBM DDRS-39130 - Ultrastar 9.1 GB Hard Drive Specifications

7.33 TEST UNIT READY (00)

Byte
7 6
0
1 LUN
2
3
4
5 VU = 0
Figure 115. TEST UNIT READY (00)
The TEST UNIT READY command allows the initiator to check if the file is READY. The SCSI specifi-
cation defines READY as the condition where the device will accept a media-access command without
returning CHECK CONDITION status.
The file will first verify that the motor is spinning at the correct speed.
If the spindle motor is not spinning at the correct speed, CHECK CONDITION status is returned with
sense key of N O T READY.
If the motor is spinning at the correct speed, the file accepts normal media access commands.
The TEST UNIT READY command is not intended as a diagnostic. No self diagnostic is performed by the
device as a result of this command.
The TEST UNIT READY command has special significance for power sequencing using the START
UNIT command with an Immediate bit of 1.
C O M M A N D COMPLETE status before the completion of motor spin-up and expects the initiator to issue
TEST UNIT READY commands to determine when the motor has reached the proper speed.
Note: The spindle automatically starts in automatic spin-up Mode. The file does not execute any com-
mands other than TEST UNIT READY, INQUIRY or REQUEST SENSE command until the the Power
On sequence is complete. The file will return CHECK CONDITION status with N O T READY sense key
and IN PROCESS O F BECOMING READY sense code for all other commands during the Power On
period.
Bit
5 4 3
Command Code = 00h
Reserved = 0
Reserved = 0
Reserved = 0
In this mode the START UNIT command returns
2 1 0
FLAG LINK
SCSI C O M M A N D SET
149