
Each partition on a tape contains a logical and physical beginning
(LBOP and PBOP) and a logical and physical end (LEOP and PEOP).
The EXB-8505 considers each partition a completely self-contained
recording area independent of the other partition on the tape. The
EXB-8505 cannot move the tape beyond the beginning or end of a
partition unless specifically requested to by a LOCATE (2Bh) or
MODE SELECT (15h) command. In effect, the EXB-8505 treats each
partition as if it were a separate tape. Figure 3-1 shows the
correspondence between the various areas on an unpartitioned tape
and on a tape with two partitions.
leader
LEOT PEOTPBOT LBOT EOD
. . .
leader
PBOT
and
PBOP 1
EOD 0
LEOT
and
LEOP 0
PEOT
and
PEOP 0
Dual-Partition Tape
. . .
PBOP 0
LBOP 0
LBOT
and
LBOP 1
EOD 1
LEOP 1
PEOP 1
Partition 1 Partition 0
Unpartitioned Tape
PBOP = Physical beginning of partition
LBOP = Logical beginning of partition
LEOP = Logical end of partition
PEOP = Physical end of partition
PBOT = Physical beginning of tape
LBOT = Logical beginning of tape
LEOT = Logical end of tape
PEOT = Physical end of tape
EOD = End of data
PBOT = Physical beginning of tape
LBOT = Logical beginning of tape
LEOT = Logical end of tape
PEOT = Physical end of tape
EOD = End of data
trailer
trailer
Figure 3-1 Corresponding areas on an unpartitioned tape and a dual-partition tape
3-24
EXB-8205 and EXB-8505
(Standard and XL)
510503
3 Implementing CTS Operations
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