Filter
Top Products
Chapter 5 ATAPI Interface
Page 82 Seagate Travan 40 Product Manual
SPACE (Group 0, Op. Code 11)
The SPACE command provides a means of positioning the tape forward or reverse
of the current position. The command can space over data blocks, filemarks,
sequential filemarks, or to the End-of-Data.
CDB for SPACE command
Data Bits
Byte 7 6 5 4 3 2 1 0 Hex
0 0 0 0 1 0 0 0 1 11
0 0 0 0 0 0
0
DFE 0X
2
3
4
MSB
Count
LSB
XX
XX
XX
5 0 0 0 0 0 0 0 0 00
DFE—Data, Filemarks, End-of-Data: The DFE field determines the type of blocks
to be spaced over.
Bit 1 Bit 0 Description
0 0 Data (Logical) Blocks
0 1 Filemarks
1 0 Consecutive Filemarks
1 1 End of Recorded Data
Count: The Count Field specifies the number of data blocks, filemarks or
consecutive filemarks to be spaced over. A value of 0 results in no tape movement
and is not considered an error. A negative value -N (2’s complement notation) results
in a logical reverse space over N blocks or filemarks ending on the BOM side of the
last block or filemark.
Spacing Over Data Blocks: The number of logical (not physical) data blocks to be
spaced over is determined by the Count Field. If a Filemark or EOD is encountered
while spacing over data blocks, tape movement is stopped and the command
terminates with a Check Condition (Status 02h). The number of data blocks
remaining to be spaced over is located in the Sense Information bytes. If termination
was caused by a Filemark, the tape is positioned following the Filemark, the Sense
Key is set to 0h (No Sense) and the FM flag bit is set. If termination was caused by
EOD (End of Recorded Data), the Sense Key will be set to Blank Check (8h). If
Logical Early Warning is encountered, the command will complete normally, but
Check Condition Status will be reported. The Sense Key will be set to No Sense (0h)
and the EOM flag bit will be set. Bad data blocks will not be reported.
Spacing Over Filemark Blocks: In Space Over Filemark mode, data blocks are
ignored. When the command terminates normally, the tape is positioned following
the last Filemark read. If EOD s encountered, the command terminates with a Check
Condition (Status 02h) and the number of Filemarks remaining to be spaced over is
located in the Sense Information bytes returned by a REQUEST SENSE command.