Abstract: The method and means of fault-tolerant processing includes a plurality of system building blocks, each including a real-time processor and specialized processors and local non-volatile memory that are coupled to communicate internally within each of the system building blocks, which, in turn, communicate with one another over local-area network links, and communicate with the remainder of the system over an I/O bus controlled by an I/O processor. Transaction-based processing is under control of a transaction coordinator which permits all of the transaction operations to complete successfully and then alter stored data for the completed transaction, or not to alter any stored data if a transaction is not completed. The transaction coordinator maintains a record of the distributed file accesses required during processing of a transaction, and prevents other transactions from altering stored data during processing of a transaction.