A Performable BSM Architecture

Abstract

This paper presents a general frame for the implementation of computer architectures characterized by a high degree of flexibility and performability. It first describes the computational model, BSM [Bon 89], based on a data-flow like programming paradigm, which is more suitable, in our opinion, to implement dependable systems than conventional imperative programming paradigms, i.e. [Hoa 78], [Han 78], [Cam 74]. BSM describes an application in a set of atomic modules, mainly functional, executed asynchronously; the modules are atomic and do not interact or communicate with other modules during execution, but release data only at their termination. The close correlation between application semantics and module structuring allows efficient redundancy scaling since criteria can be properly driven by application semantics. A structured way of inserting software redundancy in programs and the supports required for programming software fault-tolerance techniques are then introduced and discussed. The description of an on-going prototyping activity, to demonstrate the feasibility of the proposed model, is then described. The run time support, written in Parallel C, is based on “Search Mode Configurable Computer” [Mil 74] architecture and on the Q-interpreter, running on a transputer board with an Apollo Workstation as host. A BSM development environment is under implementation. A BSM compiler has been built; it generates C Parallel sources, which are linked with the Parallel C programs of the run time support and loaded using the transputer standard development system.