Abstract: A method and device for error detection includes performing error detection for each data word received in a burst access to a memory. When no error is detected, the data words are written to a cache and indicated as valid data. In response to detecting an error in a data word, the error is corrected and the corrected data written to the cache without indicating the data as valid. In addition, the location of the detected error, indicating the data symbol associated with the error, is recorded in an error vector. The error vectors associated with each data word in the burst access are compared to determine whether a detected error was properly corrected.

Abstract: Methods, apparatus, and computer program products are disclosed for clock signal synchronization among computers in a network, including designating, as a primary clock signal for all the computers in a network, a clock signal from one of the computers in the network; providing the primary clock signal, simultaneously and in parallel, from the computer whose clock signal is designated as the primary clock signal to all the other computers in the network; and providing the primary clock signal, simultaneously and in parallel, from each computer in the network to all computers in the network through multiplexers and phase locked loops, with the primary clock signal locked in phase across all the computers by a phase locked loop on each computer.

Abstract: Methods, apparatus, and computer program products are disclosed for clock signal synchronization among computers in a network, including designating, as a primary clock signal for all the computers in a network, a clock signal from one of the computers in the network; providing the primary clock signal, simultaneously and in parallel, from the computer whose clock signal is designated as the primary clock signal to all the other computers in the network; and providing the primary clock signal, simultaneously and in parallel, from each computer in the network to all computers in the network through multiplexers and phase locked loops, with the primary clock signal locked in phase across all the computers by a phase locked loop on each computer.

Abstract: Methods, apparatus, and computer program products are disclosed for clock signal synchronization among computers in a network, including designating, as a primary clock signal for all the computers in a network, a clock signal from one of the computers in the network; providing the primary clock signal, simultaneously and in parallel, from the computer whose clock signal is designated as the primary clock signal to all the other computers in the network; and providing the primary clock signal, simultaneously and in parallel, from each computer in the network to all computers in the network through multiplexers and phase locked loops, with the primary clock signal locked in phase across all the computers by a phase locked loop on each computer.

Abstract: A method and device for error detection includes performing error detection for each data word received in a burst access to a memory. When no error is detected, the data words are written to a cache and indicated as valid data. In response to detecting an error in a data word, the error is corrected and the corrected data written to the cache without indicating the data as valid. In addition, the location of the detected error, indicating the data symbol associated with the error, is recorded in an error vector. The error vectors associated with each data word in the burst access are compared to determine whether a detected error was properly corrected.

Abstract: Methods, apparatus, and computer program products are disclosed for clock signal synchronization among computers in a network, including designating, as a primary clock signal for all the computers in a network, a clock signal from one of the computers in the network; providing the primary clock signal, simultaneously and in parallel, from the computer whose clock signal is designated as the primary clock signal to all the other computers in the network; and providing the primary clock signal, simultaneously and in parallel, from each computer in the network to all computers in the network through multiplexers and phase locked loops, with the primary clock signal locked in phase across all the computers by a phase locked loop on each computer.

Abstract: A computer system having a plurality of devices which transmit and receive information over a channel is presented. The system includes, in the preferred embodiment, a central arbitration control circuit and a local arbiter associated with each device contending for channel access. Each local arbiter, corresponding to a device which desires channel access, generates a channel request signal to the central control circuit. At the appropriate time when the channel becomes available, the central control circuit generates an arbitrate signal. All local arbiters, then contending for channel access, compare the priority level on the arbitration bus with the priority value of the device it is arbitrating on behalf of, with the winning device gaining access to the channel. Each of the local arbiters contains a programmable circuit which enables the arbiter to operate either utilizing a linear priority arbitration technique or a fairness priority arbitration technique.

Abstract: A cache for use with input/output devices attached to an input/output bus. Requests for access to system memory by an input/output device pass through the cache. Access authority is checked to determine whether an input/output device is authorized to access that particular page. If it is not, access is denied. Each input/output device has access to a portion of the cache, so that activity by one device will not interfere with activity by another.

Abstract: A computer system having a plurality of devices which transmit and receive information over a channel is presented. The system includes, in the preferred embodiment, a central arbitration control circuit and a local arbiter associated with each device contending for channel access. Each local arbiter, corresponding to a device which desires channel access, generates a channel request signal to the central control circuit. At the appropriate time when the channel becomes available, the central control circuit generates an arbitrate signal. All local arbiters, then contending for channel access, compare the priority level on the arbitration bus with the priority value of the device it is arbitrating on behalf of, with the winning device gaining access to the channel. Each of the local arbiters contains a programmable circuit which enables the arbiter to operate either utilizing a linear priority arbitration technique or a fairness priority arbitration technique.

Abstract: A computer system has a cache located between input/output devices and a main system memory. All system memory accesses by the input/output devices are made through the cache. Memory accesses through the cache are limited to those addresses which are accessible to a central processor and input/output devices. All access to such addresses by the central processor are made through the cache.

Abstract: A DMA controller coupled to two separate buses controls the transfer of data between them. To effect a block data transfer, data is simultaneously read on one bus and written on the other. This allows data to be transferred between buses at the maximum transfer rate supported by the slower bus.

Abstract: A cache for use with input/output devices attached to an input/output bus. Requests for access to system memory by an input/output device pass through the cache. Virtual memory addresses used by the input/output devices are translated into real addresses in the system memory. Virtual memory can be partitioned, with some virtual addresses being mapped to a second memory attached to the input/output bus.

Abstract: A computer system can transfer data between a master subsystem and a slave subsystem on bus address lines as well as bus data lines during a high speed data transfer. Data is clocked during the high speed transfer by a high speed clock signal which is separate from a normal bus clock signal. Data is transferred at the maximum rate which can be handled by both the master subsystem and the slave subsystem.

Abstract: A DMA controller has an attached, dedicated memory. Data objects are stored on the heap and connected by pointers. Each data object contains DMA block transfer control parameters. A single block transfer made up of several separate transfers, with each separate transfer defined by one data object. The single block transfer is defined by linking several data objects into a list. The DMA controller consecutively performs the transfers in a linked list without requiring control by a system central processor.

Abstract: A computer system bus includes signal lines for controlling a high speed block data transfer mode between a bus master and a bus slave. When both devices support such a transfer, a high speed bus clock separate from the normal bus clock is used to transfer data. Devices not involved in the high speed block transfer see only an extended normal data transfer. The master and slave use bus control signals to determine the speed and data width of the high speed transfer. If the slave is unable to transfer the complete block of data at the high speed clock rate, it can signal the master to repeat the transfer of individual data items as necessary.

Abstract: A computer system has a cache located between input/output devices and a main system memory. All system memory accesses by the input/output devices are made through the cache. Memory accesses through the cache are limited to those addresses which are accessible to a central processor and input/output devices. All access to such addresses by the central processor are made through the cache.

Abstract: A computer system can transfer data between a master subsystem and a slave subsystem on bus address lines as well as bus data lines during a high speed data transfer. Data is clocked during the high speed transfer by a high speed clock signal which is separate from a normal bus clock signal. Data is transferred at the maximum rate which can be handled by both the master subsystem and the slave subsystem.