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Product Manual - Disc Drive SCSI-2/SCSI-3 Interface (Vol. 2; Ver. 2), Rev. E
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5.0
Command descriptions
Two types of commands are supported by the disc drive: commands for all devices; and commands for direct
access devices. In each of these categories the disc drive supports only Group 0, Group 1 and Group 2
commands.
5.1
Command descriptions for all device types
5.1.1
Group 0 commands for All Device Types
The disc drive implements the following Group 0 commands that are applicable for all device types. See
Table 5.1.1-1.
Table 5.1.1-1. Group 0 Commands for all device types
Command
Applicable
OP Code*
Command Name
Section
00h
Test Unit Ready
5.1.1.1
03h
Request Sense
5.1.1.2
12h
Inquiry
5.1.1.3
1Ch
Receive Diag.
5.1.1.5
Results
1Dh
Send Diagnostic
5.1.1.6
*Byte 0 of Command Descriptor Block.
5.1.1.1
Test Unit Ready (00h)
The Test Unit Ready command provides a means to verify the logical unit is ready. This is not a request for a
self test. If the logical unit (drive) can accept an appropriate medium access command without returning
check condition status, the drive returns a Good status. See Table 5.1.1-2 for proper format.
Table 5.1.1-2. Test Unit Ready Command
Bit
7
6
5
4
3
2
1
0
Byte(s)
0
0
0
0
0
0
0
0
0
1
Logical Unit No.
0
0
0
0
0
0
0
0
2
0
0
0
0
0
0
0
0
3
0
0
0
0
0
0
0
0
4
0
0
0
0
0
0
0
0
5
0
0
0
0
0
0 Flag Link [2]
Notes.
[1] Logical Unit No. must be zero.
[2] See “Control Bytes”, paragraph 4.2.6.
If the drive cannot become operational or is in a state such that an initiator action (e.g., START command) is
required to make the unit ready, the drive returns CHECK CONDITION status with a Sense Key of NOT
READY. One of several possible Additional Sense codes indicates the reason for the NOT READY condition.
