Browse Prior Art Database

Field Replaceable Unit Isolation in a Dual-Bus System

IP.com Disclosure Number: IPCOM000120518D
Original Publication Date: 1991-May-01
Included in the Prior Art Database: 2005-Apr-02
Document File: 2 page(s) / 83K

Publishing Venue

IBM

Related People

Aldereguia, A: AUTHOR [+3]

Abstract

This article describes a technique and hardware enablement for stopping bus masters from accessing the local bus in a computer system and potentially corrupting the system if broken.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Field Replaceable Unit Isolation in a Dual-Bus System

      This article describes a technique and hardware
enablement for stopping bus masters from accessing the local bus in a
computer system and potentially corrupting the system if broken.

      One of the requirements associated with any computer system is
the ability to isolate defective field replaceable units (FRUs)
during power-on self-test (POST) or while running diagnostics.  The
maintenance person can then identify and replace the failing FRU.
Examples of FRUs are: planar boards, processor cards, cache cards,
option cards, single inline memory modules (SIMMs), hardfiles and
floppy diskettes.  Typically, accurate FRU isolation is not possible,
since each FRU is interlaced and a failure in any one FRU causes the
entire system to be non-operational.  If the system is
non-operational, POST does not have the ability to identify the
actual failing FRU.  FRU isolation is complicated in a dual-bus
system, since there is independent operation possible on two buses:
the CPU local bus and the system bus.

      The CPU local bus contains the ROM and the processor which
executes the POST program.  The program is structured to test the
FRUs in the system in the following order: processor card, memory,
cache card, planar, files, and option cards.  POST will enable and
test each FRU until the system passes POST or there is a failure and
that FRU is identified as needing replacement.  The structured test
can still provide erroneous failure information if a device on the
system bus injects a defect that causes failure of a CPU bus
component.  The system bus and its devices can be isolated from the
CPU bus by the technique disclosed herein.

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