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Section
1
Introduction
The MSU0402IMSU0451 Mass Storage Units are high-capacity disk storage sub-
systems with advanced microprogrammed control and operating features that
improve response time and throughput. The MSU0402 is identical in appearance
and operation
to
the MSU0451 and may be field-upgraded (see Options) to an
MSU0451. Up
to
32 of these disk units per mass storage processor can be connected
to any Large System. The disk units are controlled by physically integrated or
freestanding mass storage processors (described in Appendix A).
Data Integrity and Protection
The integrity and protection of data is ensured by the following features:
• Write protect capability- Individual write-protect push button for each disk
unit excludes the possibility of recording on protected files.
• Automatic unloading - Heads automatically unload when specific conditions,
such as low rotational speed or loss of power, are detected.
• Power fault sensing - If an ac or dc power fault has occurred, recording cannot
take place.
• Write current monitoring - Write current is inhibited during seeks or without
command and loss is detected during a write command.
• Check code insertion- The validity of recorded information is ensured by the
insertion of characters of check information
C~check
code") in each record.
• Parity checking - The device monitors command and data lines for odd parity; if
even parity is detected, a fault is set.
• Temperature sensing - Temperatures greater than equipment specifications
are displayed and an audible alarm sounded.
• Head offset - Heads may be offset by command to facilitate data recovery.
• Nolmultihead select- The device checks for no/multiheads being selected,
which will produce a fault condition.
Introduction
1-1
AT71-03
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