Improved 3-Line Hardware Synchronization

A new procedure is proposed to synchronize processors of a distributed system, which concurrently execute a common process consisting of a sequence of operations. The procedure is an extension of that used for the 1987 IEEE Futurebus Standard. It is based on global synchronization lines and a distributed synchronizer, and requires only minor modifications of existing hardware. The procedure allows to carry out two alternative synchronization protocols. As usual, an operation may be terminated by the last processor having finished its part of the operation. Alternatively, the operation may also be terminated by the first processor being ready. Application of this second procedure, e.g., to bus arbitration, allows to reduce the arbitration time in average by a factor of 2