In a data processing system, a plurality of modules connected to a system bus thereof are assigned with identifiers. When a source module initiates a split read access to another module, the source module sends an address of the access destination module and an identifier of the source module. When sending a response to the source module, the destination module returns response data and the identifier of the source module thereto. Checking the identifier from the destination module, the source module determines the response data returned as a response to the initiated access.

Bus control system

An open high-speed local system bus for a microcomputer system which is decoupled from I/O and provides a consistent interface to the CPU subsystem, memory subsystem, graphics subsystem and peripheral subsystem. The local system bus supports discrete and burst transactions, pipelining in both the transactions, multiple microprocessor and distributed interrupts.

Open high speed bus for microcomputer system

A digital data processing device includes a bus for transmitting signals (e.g., data and/or address information) between plural functional units (e.g., a central processing unit and a peripheral controller). A first such unit includes first and second processing sections that concurrently apply to the bus complementary portions of like information signals (e.g., longwords containing data). A fault detection element reads the resultant signal from the bus and compares it with at least portions of the corresponding signals originally generated by the processing sections themselves. If there is discrepancy, the fault-detector signals a fault, e.g., causing the unit to be taken off-line. By use of a redundant unit, processing can continue for fault-tolerant operation.

Digital data processing methods and apparatus for fault detection and fault tolerance

A computer system having multiple processors interconnected by a pended bus provides exclusive read-modify-write operations employing multiple lock bits. A processor generates an interlock read command which is transmitted as a transfer over the pended bus to a memory or I/O node. Acknowledge confirmations are transmitted by the memory back to the processor two bus cycles after each bus cycle of the processor transfer. The processor transfer, including an interlock read command, is stored in a input queue in memory and processes in turn by the memory. A first interlock read command to a specified memory location causes a lock bit to be set for that location and a first type of response message including the contents of the specified location to be generated by the memory and stored in an output queue. The memory obtains access to the pended bus through an arbitration process and transmits a response message including the contents of the memory location specified in the interlock read command at an unspecified time after initiation of the interlock read command. A subsequent interlock read command from the processor to the same memory location will result in a denial of access to the specified location and in the generation of a second type of response message by the memory which indicates that the specified location is locked.

Method and apparatus for managing multiple lock indicators in a multiprocessor computer system

An integrated circuit, such as an integrated circuit memory or buffer device, method and system, among other embodiments, generate a plurality of error codes, such as CRC codes, corresponding to control information, write data and read data transactions, respectively. The plurality of separately generated CRC codes is logged or stored in respective storage circuits, such as circular buffers. The stored plurality of CRC codes corresponding to each transaction then may be used to determine whether an error occurred during a particular transaction and thus whether a retry of the particular transaction is issued. The integrated circuit includes a compare circuit to compare a CRC code generated by the integrated circuit with a CRC code provided by a controller device. A CRC code corresponding to read data is transferred to a controller device using a data mask signal line that is not being used during a read transaction. The CRC code generated by the integrated circuit then may be compared to a CRC code generated by the controller device to determine whether an error occurred. The controller device generates and stores a plurality of CRC codes, corresponding to control information, write data and read data. The controller device then compares the CRC codes generated by the controller device with CRC codes generated and stored in the integrated circuit to determine whether an error has occurred during a particular transaction.

System to detect and identify errors in control information, read data and/or write data

A digital data processing system including a number of input/output units (12) that communicate with a memory (11) over an input/output bus (30) and through an input/output interface (31). The input/output interface (31) pipelines transfer between the input/output units (12) and the memory (11). In the event of an error in the input/output interface's pipeline buffer, it transmits information to the input/output (12) that initiated the transfer unit to enable it to re-initiate the transfer.

Stephen T. Pomfret

Papers

Bus for data processing system with fault cycle operation

Datenverarbeitungssystembus mit Fehlerzyklusbetrieb