Showing papers on "Control reconfiguration published in 1971"

Logic Design for Dynamic and Interactive Recovery

Abstract: Recovery in a fault-tolerant computer means the continuation of system operation with data integrity after an error occurs. This paper delineates two parallel concepts embodied in the hardware and software functions required for recovery; detection, diagnosis, and reconfiguration for hardware, data integrity, checkpointing, and restart for the software. The hardware relies on the recovery variable set, checking circuits, and diagnostics, and the software relies on the recovery information set, audit, and reconstruct routines, to characterize the system state and assist in recovery when required. Of particular utility is a handware unit, the recovery control unit, which serves as an interface between error detection and software recovery programs in the supervisor and provides dynamic interactive recovery.

Two-Level Control of Interconnected Power Plants

Abstract: A two-level controller for interconnected power plants is discussed. Each plant has a first level local optimal or suboptimal controller. The second level of control is an intervention control performed by a central co-ordinator. If a sudden system disturbance causes the system angular acceleration to exceed preset tolerances a priority interrupt to the central co-ordinator initiates intervention control. Angular velocity deviations of all plants are transmitted to the co-ordinator. This data is used to generate coefficient data for each plant. On receiving its coefficient data, each plant generates a local second-level intervention control which augments first level local control.

Dynamic reconfiguration in a modular computer system

Abstract: This thesis presents an orderly design approach for dynamically changing the configuration of constituent physical units in a modular computer system. Dynamic reconfiguration contributes to high system availability by allowing preventative maintenance, development of new operating systems, and changes in system capacity on a non-interference basis. The design presented includes the operating system primitives and hardware architecture for adding and removing any (Primary or secondary) storage module and associated processing modules while the system is running. Reconfiguration is externally initiated by a simple request from a human operator and is accomplished automatically without disruption to users of the system. This design allows the modules in an installation to be partitioned into separate non-interfering systems. The viability of the design approach has been demonstrated by employing it for a practical implementation of processor and primary memory dynamic reconfiguration in the Multics system at M.I.T.

A Three-Failure-Tolerant Computer System

Abstract: Two basic factors influence the design of highly reliable computer systems: the amount of failures required to be tolerated and the reliability or MTBF required. A computer system designed to tolerate any three single failures in a fail-operational–fail-operational–fail-safe manner for a real-time control application is presented. The design approach uses adaptive majority voting in both hardware and software with a four-level redundant system. Various methods of performing the adaptive majority voting functions were evaluated with the selected approach using a special module termed a voter–comparator switch (VCS). The VCS module allows the computer system to be operated in a variety of redundant modes, depending on the failure tolerance required at any particular time.

The Data Reconfiguration Service: An Experiment in Adaptable, Process

Abstract: Describes the Data Reconfiguration Service (DRS) now being implemented at MIT, UCLA, UCSB and RAND for the ARPA computing network.