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•
Microcode-controlled power sequencing and power and temperature
monitoring performed by the support processor
The following diagnostic facilities are provided:
•
Online Test Executive Program (OLTEP) and Online Tests (OLTs) that
execute under operating system control and provide online diagnosis of
channel-attached 1/0 devices for most devices that attach to 4381 Processors
•
System Test for checking the basic operating capability of a 4381 Processor
Problem analysis routines provided in microcode that the operator can execute
to aid in hardware fault location
•
Microdiagnostics for the components of a 4381 Processor (instruction
processing function, processor storage, support processor, etc.)
•
Manual operations that the customer engineer can perform using the operator
console and appropriate support documentation
•
A Remote Support Facility that enables the on-site customer engineer to access
a remote data bank and allows malfunction diagnosis to be performed by a
remote customer engineer at a support center
The hardware and programmed recovery aids are designed to improve system
availability. Hardware reconfiguration is used where possible to permit the system
to run with normal performance or in a degraded mode, when necessary, so that
maintenance can be deferred. When solid failures that cannot be circumvented do
occur, their impact can be reduced by utilizing the expanded diagnostic facilities,
.,,,_
such as Problem Analysis, which are designed to reduce the time required to isolate
and repair a malfunction.
60:10 Recovery Features
Additional hardware and microcode, which attempts correction of most hardware
errors without programming assistance and performs certain reconfiguration
operations, is included as a basic part of a 4381 Processor. The control program
can be notified, via an interruption, of both intermittent and solid hardware errors
so that error recording and recovery procedures can take place.
Automatic Instruction Retry
If
a hardware error is detected during the execution of instructions, the failing
instruction is automatically retried once by the processor without programming
assistance if it is a retryable instruction. The error retry procedure is initiated by
the support processor. The data required for a retry is saved during the execution
of instructions.
The following instructions are retryable at any point during their execution (see
System/ 3 70 Principles of Operation
for the instructions in each instruction group):
98
A Guide to the IBM 4381 Processor
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