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malfunctioning bit in the associated directory entry, as is done when
reconfiguration is not possible.
20:15 Support Processor Subsystem
Components and Functions
The support processor subsystem provides basic operational functions for 4381
Processors and is the primary maintenance tool for diagnosing hardware
malfunctions. It is designed to maximize total system availability and to provide
rapid fault location and repair, where possible.
The components of the support processor subsystem are the support processor,
support bus adapter, local channel adapter, console attachment adapter and
attached devices, power adapter, power information panel, common
communications adapter for the Remote Support Facility, and two system diskette
drives and associated adapters.
While the support processor subsystem in 4381 Processors has the same types of
functional components as those in 4341 Processors, certain of the physical
components in this subsystem in 4381 and 4341 Processors are not the same.
Specifically, the support processor in 4381 Processors is different.
It
is faster and
more reliable (because of more dense technology) than that in 4341 Processors and
has twice the storage capacity. The 4381 support processor is implemented on one
card (the 4341 support processor requires four cards) and is program compatible
with the 4341 support processor. In addition, a number of support logic cards have
been eliminated or reassigned to make the support processor subsystem more
efficient and to aid in easier fault location. A dump-to-diskette button on the
processor control panel on the 4381 Processor can be used to dump the contents of
support processor storage to diskette (functional diskette 2). This dump
information can be sent to the IBM Support Center for analysis when error history
is required to aid in problem determination.
The same two-sided diskettes (with a IM-byte capacity) are used in 4381 and 4341
Processors but a different diskette drive is used in 4381 Processors and there are
two diskette drives in the 4381 instead of one. The two diskette drives in a 4381
Processor fit in the same space as the single diskette drive in a 4341 Processor.
Two diskette drives are required in a 4381 Processor in order to support
System/370-XA mode of operation. The second diskette drive also allows some
Problem Analysis routines to be kept online for operator use to avoid diskette
changing.
In addition, communication between the support processor and the instruction
processing function has been improved in 4381 Processors when compared with
the 4341 implementation (see discussion under "Support Bus Adapter" in this
subsection).
The microcoded support processor controls the operation of the support processor
subsystem. The support processor subsystem is responsible for the following:
42
A Guide to the IBM 4381 Processor
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