05295258 is referenced by 159 patents and cites 112 patents.

A computer system in a fault-tolerant configuration employs multiple identical CPUs executing the same instruction stream, with multiple, identical memory modules in the address space of the CPUs storing duplicates of the same data. The system detects faults in the CPUs and memory modules, and places a faulty unit offline while continuing to operate using the good units. The faulty unit can be replaced and reintegrated into the system without shutdown. The multiple CPUs are loosely synchronized, as by detecting events such as memory references and stalling any CPU ahead of others until all execute the function simultaneously; interrupts can be synchronized by ensuring that all CPUs implement the interrupt at the same point in their instruction stream. Memory references via the separate CPU-to-memory busses are voted at the three separate ports of each of the memory modules. I/O functions are implemented using two identical I/O busses, each of which is separately coupled to only one of the memory modules. A number of I/O processors are coupled to both I/O busses. I/O devices are accessed through a pair of identical (redundant) I/O processors, but only one is designated to actively control a given device; in case of failure of one I/O processor, however, an I/O device can be accessed by the other one without system shutdown.

Title
Fault-tolerant computer system with online recovery and reintegration of redundant components
Application Number
455218
Publication Number
5295258
Application Date
January 5, 1990
Publication Date
March 15, 1994
Inventor
Nikhil A Mehta
Austin
TX, US
Kenneth C Debacker
Austin
TX, US
John Pozdro
Austin
TX, US
Kyran W Fey Jr
Pfluggerville
TX, US
Donald C Westbrook deceased
late of Austin
TX, US
Richard W Cutts Jr
Georgetown
TX, US
Randall G Banton
Austin
TX, US
Brian Vetter
Austin
TX, US
Tom Bereiter
Austin
TX, US
Douglas E Jewett
Austin
TX, US
Agent
Graham & James
Assignee
Tandem Computers Incorporated
CA, US
IPC
G06F 12/16
G06F 11/20
G06F 11/18
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