Space Command
226 T10000: Interface Reference Manual August 2016
Space Command
The Space command moves the logical position of the tape. Any buffered write data
and filemarks are written on the tape before this operation starts. Note: The Space
command does not always move tape.
Notes:
1. A zero in the Count field does not move tape.
2. If a filemark is encountered during a Space Blocks command, Check Condition
status is returned and the tape is positioned past the filemark. The Valid and
Filemark bits in the sense data are set and the Information Bytes are set to the
Count minus the actual number of blocks moved (not counting the filemark).
3. If an end-of-data is encountered during any space command (except space to end
of data), Check Condition status is returned and the tape is positioned after the
last valid record.
For space blocks and filemarks, the Valid bit is set and the Information Bytes
contains the Count minus the actual number of blocks or filemarks moved. The
Sense Key is set to Blank Check. If the tape is positioned past LEOT, EOM is also
set.
4. A forward space into PEOT returns Check Condition status and sets the EOM bit,
and a sense key of Media Error. The information bytes contain the count minus
the actual number of blocks or filemarks moved.
TABLE 3-171 Space Command
Byte
Bit
76543210
0 Operation Code (11h)
1 Reserved Code
2
thru
4
(MSB)
Count
(LSB)
5 Control Byte
Parameter Value
Code Type of space operation:
000b = Space blocks
001b = Space filemarks
011b = End-of-data (EOD)
Count Number of blocks or filemarks to move.
A negative count (two’s complement notation) moves tape in reverse direction
(toward BOT).
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