Abstract: A method includes transmitting, by a first processing device, a signal to a second relay processing device. The signal includes a message for the second relay processing device to transmit a read command and/or a write command to an I/O device that is not accessible by the first processing device. The method also includes receiving, by the first processing device, an indication that the second relay processing device has transmitted the read command and/or the write command to the I/O device.

Abstract: A method includes transmitting, by a first processing device, a signal to a second relay processing device. The signal includes a message for the second relay processing device to transmit a read command and/or a write command to an I/O device that is not accessible by the first processing device. The method also includes receiving, by the first processing device, an indication that the second relay processing device has transmitted the read command and/or the write command to the I/O device.

Abstract: A module of a distributed process control system has a prior art kernel submodule, a peripheral submodule, and an interface circuit to provide for communications between the two submodules. The kernel submodule communicates with the interface circuit over a module BUS which includes a data BUS and an address BUS. The peripheral submodule communicates with the interface circuit over a peripheral component interface (PCI) BUS, a single thirty two bit BUS which is incompatible with the module BUS. The interface circuit permits such communications between the two submodules without requiring any hardware or software changes to the kernel submodule and the module BUS, nor to components of the peripheral submodule or its PCI BUS. The interface circuit includes interface registers, a control circuit which determines which submodule is permitted to write or read data and/or address into or from a given register of the interface registers.

Abstract: A memory unit, made up of a plurality of BY-4 memory devices, has a plurality of computer words, each computer word including a predetermined number of data bits and a predetermined number of check bits. An error detection and correction (EDAC) apparatus interfaces with the memory unit for detecting and correcting a single bit error of the computer word, detecting a two bit error of the computer word, and detecting all two, three, and four bit errors of a single memory device. Matrix logic generates the check bits from preselected participating data bits of the data bits of the computer word being fetched. Compare gate logic compares check bits from the memory unit to corresponding check bits generated by the matrix logic to generate syndrome bits.

Abstract: A local area network has a plurality of modules, each module having a corresponding timing subsystem. Each timing subsystem includes a clock unit for generating clock pulses, and an a.c. power source. Each timing subsystem is capable of having the timing information generated by each timing subsystem substantially synchronized to the timing information generated by a timing subsystem designated as a master timing subsystem. Each timing subsystem includes a first element, adapted to receive clock pulses and an a.c. reference signal generated from an a.c. power source, which generates timing information from the clock pulses or the a.c. reference signal in response to commands from the module. A register element stores the timing information generated. A second element updates the timing information stored in the register element with timing information included in a timing frame in response to a predetermined command from the module.

Abstract: Method and apparatus for synchronizing to a desired degree of accuracy the timing subsystems of the modules of a distributed local area network by the master and the slave. Each module includes a Module Central Processing Unit (MCPU) and a source of clock signals. Each MCPU includes a digital timing subsystem which produces a fine timing, a synchronization, and a real time timing signal. Two of the timing subsystems are provided with driver circuits one designated as the master and the other as the slave. Each timing subsystem, alternately receives the timing frames transmitted over the two cables of the network by the master and the slave. All timing subsystems other than the master, synchronize with the master. The slave transmits its timing frame in synchronization with the master.

Abstract: A computer system includes at least on error detecting circuit for checking data bits and an associated check bit to verify that the data does not contain an error. An apparatus for verifying the operation of the error detection circuit comprises a generator unit operatively connected to said data lines for receiving data bits, for outputtting a verification signal and a check bit signal. The verification signal indicates the validity of the data bits during a read operation, and the check bit signal is generated during a write operation. A gate element having an input terminal to receive at least one check bit controls at least one input to the generator unit. A first control signal is transmitted to the generator unit thereby causing the check bit signal generated by the generator unit to be valid or invalid in response to the first control signal. Further, the check bit associated with the data is transmitted to the generator unit in response to a second control signal.

Abstract: A method of synchronizing a digital timer with the frequency of a source of A.C. power to provide long term temporal stability. The timer produces internal, fine resolution, synchronization and real time timing signals from a source of clock signals. The periods of all the timer produced timing signals are integral multiples of the period of its internal timing signal.A.C. reference timing signals which are a function of the frequency of the source of A.C. power are applied to the timer. The quotient of the period of the synchronization timing signals by that of the A.C. reference timing signals is an integer "n". Once n is determined, the number of fine resolution timing signals in each synchronization period for every n.sup.th A.C. timing signal is compared with a reference value. The timing of the fine resolution timing signals is adjusted to maintain the number of fine resolution timing signals in each synchronization period at which the n.sup.th A.C.