Singer 40 User Manual

6 MULTI-PARTITION CONSIDERATIONS
A disc drive is free for use if it is not bound to a partition. A disc drive is
bound to a partition as soon as the partition initiates a seek 1 upon that drive. A
drive which is bound to a partition remains so until the associated input or out-
put operation is complete. When a disc drive is bound to a partition, no other
partition may initiate a seek upon that drive.
In an installation containing several disc drives, all the drives may be per-
forming seeks simultaneously; however, only one drive may be transmitting
data at a time.
The Disc Controller remembers which disc drives are bound to which partitions.
If several seeks are being performed simultaneously, the first partition to gain
control of the central processor after that partition's seek is complete pre-
empts the F AC for data transmission. Once data transmission is begun, the
partition may read and/or write sectors as long as the partition maintains
control of the central processor and does not try to move the read/write head
mechanism to another track. If the partition attempts to move the read/write
head mechanism, the partition relinquishes control of the central processor
and the disc drive is freed.
If an instruction addresses a disc drive which is bound to another partition, the
partition in which the instruction is executed relinquishes control of the central
processor and does not regain control until the disc drive is free.
If an instruction addresses a disc drive which is free but the operation requires
that the read/write head mechanism be moved, the seek is initiated (the drive
becomes bound) and the partition in which the instruction is executed relin-
quishes control of the central processor and does not regain control until the
seek is complete.
1 The term "seek" refers to the act of moving the read/write head mechanism to the
proper track in response to a Read or Write instruction executed in the central
processor.
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Models 40 and 42 Reference Manual 6-1

Singer 40 Specifications

General

Brand	Singer
Model	40
Category	Storage
Language	English