Load Unload; Command Descriptor Block - Seagate Viper 200 Scsi Interface Manual

SCSI Commands

LOAD UNLOAD

Command Descriptor Block

Field Descriptions
The Load Unload command may be used to load or unload a cartridge. This
command may also be used to request that the retension function be performed.
Bits
Byte 7 6
0
1 Ignored LUN
2
3
4 Reserved
5
Field Bytes Bits
Operation 0
Code
Ignored 1 5-7
Logical
Unit
Immed 1 0
Hold 4 3
EOT 4 2
Reten 4 1
Load 4 0
Reserved
Control 5
The drive has three possible states where the medium may be positioned. The
locations are:
•
The Medium Loadable Position where the medium is inserted into the drive but
has not been seated into the drive and the tape has not been threaded to BOT.
•
The Medium Auxiliary Memory Accessible Position where the medium has been
seated into the drive but the tape has not been threaded to BOT.
•
The Medium Loaded And Ready Position where the medium has been seated
into the drive and the tape has been threaded to BOT. The medium is ready to
use.
5 4 3
Operation Code (1Bh)
Reserved
Reserved
Reserved
Hold
Control
Description
The Operation Code for the Load Unload command is 1Bh.
The LUN field is residual from the SCSI-1 days and is ignored.
0 = Status is not returned until the operation has completed.
1 = Status is returned as soon as buffered data, filemarks have
been written to the medium and the CDB has been validated.
1 = Requests that the medium be positioned to the Medium Auxil-
iary Memory Accessible position where the medium is seated
into the drive but the tape is not threaded to BOT.
Not supported. Must be set to 0.
1 = Requests that the retension function be performed on medium.
0 = requests that the medium be unloaded.
1 = requests that the medium be loaded.
All reserved bits must be 0.
See Control Byte Format on page 18.
Page 33
2 1 0
Immed
EOT Reten Load