Abstract: A high-performance, high-reliable backplane bus has a simple configuration and operation. An error reporting network (ERN) provides an inexpensive approach to collecting the error state of a whole system in a uniform and consistent way. The uniformity allows for simpler interface software and for standardized hardware handling of classes of errors. In a preferred embodiment, serial error registers are used, minimizing implementation cost and making the software interface to the serial registers much easier. Serial error information is transferred over a separate data path from the main parallel bus, decreasing the chance of the original error corrupting the error information. Each CPU is provided with a local copy of the entire body of error information. The redundancy minimizes the impact of a possible CPU failure and allows the CPUs to coordinate error recovery.

Abstract: A high-performance, high-reliable backplane bus has a simple configuration and operation. An error reporting network (ERN) provides an inexpensive approach to collecting the error state of a whole system in a uniform and consistent way. The uniformity allows for simpler interface software and for standardized hardware handling of classes of errors. In a preferred embodiment, serial error registers are used, minimizing implementation cost and making the software interface to the serial registers much easier. Serial error information is transferred over a separate data path from the main parallel bus, decreasing the chance of the original error corrupting the error information. Each CPU is provided with a local copy of the entire body of error information. The redundancy minimizes the impact of a possible CPU failure and allows the CPUs to coordinate error recovery.

Abstract: A computer bus includes a first original signal line, a second redundant signal line, circuitry connected to the first original signal line and the second redundant signal line for driving the first original signal line and the second redundant signal line so as to convey on each identical information, circuitry for receiving signals on the first original signal line and the second redundant signal line, and error checking circuitry for comparing the signals on the first original signal line and the second redundant signal line and for indicating an error if the signals differ. By providing redundant signals for each signal that cannot be check with parity (for example wired-OR signals), the potential for single undetected points of failure is eliminated. In accordance with another embodiment of the invention, a computer having multiple modules connected by a backplane bus.

Abstract: A computer having multiple modules connected by a backplane bus includes multiple competition signal lines and multiple class signal lines. Access to the backplane bus to engage in one or more of multiple types of bus transactions is arbitrated between the modules by classifying the bus transactions into different classes and, during each of a succession of competition cycles, when a module wants access to the backplane bus to engage in a particular type of bus transaction, asserting a class signal line corresponding to a class in which the particular type of bus transaction has been classified. Based on information presented on the class signal lines, it is determined which modules are or are not eligible to compete for access to the backplane bus. When a module is eligible to compete for access to the backplane bus, it drives an identification code associated with the module on the competition signal lines.