Abstract: A technique for identifying multiple circuit components. More specifically, a technique for identifying the location of electrical components, such as memory cartridges which have been disposed on a substrate, is described.

Abstract: An architecture, system and method are provided for efficiently transferring data across multiple processor buses. Cache coherency is maintained among cache storage locations within one or more of those processors, even in instances where a hit-to-modified condition occurs to those cache storage locations. A guaranteed access is maintained to bus agents operating on a first processor bus so that out-of-order or split transactions are prevented on that bus even under conditions of a hit-to-modified condition. One or more of the other processor buses undergo a defer transaction, yielding an out-of-order condition which is resolved after the initial transaction and a snoop request cycle has been placed upon the first processor bus. The present architecture, system and method thereby prevents live-lock conditions, and does so without automatically deferring each transaction yielding a hit-to-modified signal.

Abstract: A computer system includes a plurality of memory modules that contain semiconductor memory, such as DIMMs. The system includes a host/data controller that utilizes an XOR engine to store data and parity information in a striped fashion on the plurality of memory modules to create a redundant array of industry standard DIMMs (RAID). The host/data controller also interleaves data on a plurality of channels associated with each of the plurality of memory modules.

Abstract: A method of replacing a memory module in a computer system. Specifically, a method for replacing a memory module in a segment of a redundant memory system, without powering-down the memory system.

Abstract: A system and technique for detecting and classifying data errors in a memory device. More specifically, hard and soft data errors in a memory device are detected by initiating a READ request initiated from a host controller. If an error is detected, the data is corrected and re-written to the corresponding memory location. A second READ request is then issued to read the corrected data. If a second error is detected in the corrected data, the error is classified as a hard error and a counter is incremented to track the number of hard errors detected in the system Once a programmable threshold number of hard errors are detected in a particular memory segment, an indicator, such as a light emitting diode (LED), is used to indicate that the corresponding memory segment should be replaced.

Abstract: A method of adding memory capacity to a computer system. The computer system comprises a redundant memory system including a plurality of memory cartridges. By powering-down a memory cartridge, adding an additional memory module to the memory cartridge, and powering-up the memory cartridge for each memory cartridge in the system, the system can transition from a redundant mode of operation to a non-redundant mode of operation for each power-down, thus allowing the computer system to remain functional during the addition of the memory module. Alternatively, memory cartridges with higher memory capacity than those currently present in the computer system can be used to replace existing memory cartridges in the computer system, using the same techniques.

Abstract: A processor-based device having a plurality of memory cartridges secured within a chassis by a lever system. The processor-based device comprises an indication system to indicate memory system operating conditions. Each memory cartridge has a protective assembly to protect memory elements within the memory cartridge when the memory cartridge is removed from the processor-based device. The processor-based device is operable such that at least one memory cartridge may be removed from the processor-based device without affecting operation of the processor-based device.

Abstract: A hot-pluggable memory cartridge for use in a redundant memory system. More specifically, the control logic and method for implementing a plurality of memory cartridges which may be hot-plugged into a memory sub-system.

Abstract: The control logic for a hot-pluggable memory cartridge for use in a redundant memory system. To implement a hot-pluggable memory cartridge in a redundant memory system, control logic to control the sequence of events for powering-up and powering-down a memory cartridge is provided.

Abstract: A technique for identifying multiple circuit components. More specifically, a technique for identifying the location of electrical components, such as memory cartridges which have been disposed on a substrate, is described.

Abstract: A system and technique for correcting data errors in a memory device. More specifically, data errors in a memory device are corrected by scrubbing the corrupted memory device. Generally, a host controller delivers a READ command to a memory controller. The memory controller receives the request and retrieves the data from a memory sub-system. The data is delivered to the host controller. If an error is detected, a scrub command is induced through the memory controller to rewrite the corrected data through the memory sub-system. Once a scrub command is induced, an arbiter schedules the scrub in the queue. Because a significant amount of time can occur before initial read in the scrub write back to the memory, an additional controller may be used to compare all subsequent READ and WRITE commands to those scrubs scheduled in the queue.

Abstract: A system and technique for detecting data errors in a memory device. More specifically, data errors in a memory device are detected by initiating an internal READ command or verify operation from a set of logic which is internal to the memory system in which the memory devices reside. Rather than relying on a READ command to be issued from an external device, via a host controller, the verify logic initiates verify routine in response to an event such as an operator instruction, hot-plug operation, or a periodic schedule. By implementing the verify operation, the system does not rely on external READ commands to verify data integrity. The verify routine may rely on typical ECC error logging mechanisms and may be used in a RAID memory architecture. Further, the verify routine may be used in conjunction with other error logging and correction logic, as well as scrubbing logic.

Abstract: A computer system includes an apparatus which enables transactions directed to a particular target device such as one situated inside a bridge to be shunted directly to the device without requiring that the transaction actually proceed to the device through a bus on which the device is located. However, the transaction may, in fact, also be run on the bus on which the device is located, the ID select for the target device may be masked. In this way, it is possible to run transactions to a particularly critical device even when the bus on which it is located is, for one reason or another, not operating.

Abstract: A computer system includes a plurality of memory modules that contain semiconductor memory, such as DIMMs. The system includes a host/data controller that utilizes an XOR engine to store data and parity information in a striped fashion on the plurality of memory modules to create a redundant array of industry standard DIMMs (RAID). The system supports DIMMs having X4 and X8 configurations. The system also transitions between various states, including a redundant state and a non-redundant state, to facilitate “hot-plug” capabilities utilizing its removable memory cartridges.

Abstract: A system and technique for detecting data errors in a memory device. More specifically, data errors in a memory device are detected by initiating an internal READ command or cleansing operation from a set of logic which is internal to the memory system in which the memory devices reside. Rather than relying on a READ command to be issued from an external device, via a host controller, the cleansing logic initiates a cleansing routine in response to an event such as an operator instruction or a periodic schedule. By implementing the cleansing operation, the system does not rely on external READ commands to verify data integrity. Further, a monitoring device is coupled between the cleansing logic and a memory scheduler. The monitoring device provides a feed back mechanism from which to vary the frequency of certain memory requests such as the cleansing and scrubbing operations. The cleansing routine may rely on typical ECC error logging mechanisms and may be used in a RAID memory architecture.

Abstract: A computer system includes a first device on a first data bus, a second device on a second data bus, and a bridge device that delivers data transactions between the two devices. The bridge device includes an execution queue that stores only a higher priority transaction and transactions initiated before the higher priority transaction, and a controller that selects transactions from the execution queue to be completed on one of the data buses.

Abstract: A computer system includes an apparatus which enables transactions directed to a particular target device such as one situated inside a bridge to be shunted directly to the device without requiring that the transaction actually proceed to the device through a bus on which the device is located. However, the transaction may, in fact, also be run on the bus on which the device is located, the ID select for the target device may be masked. In this way, it is possible to run transactions to a particularly critical device even when the bus on which it is located is, for one reason or another, not operating.

Abstract: A computer system includes a memory device on the first data bus, a requesting device that initiates a delayed memory read transaction on a second data bus, and a bridge device that delivers the delayed memory read transaction to the first data bus and receives from the first data bus completion data requested in the memory read transaction. The bridge device includes a data storage buffer that stores the completion data, and a buffer management element that automatically requests from the memory device additional data to be placed in the data storage buffer.

Abstract: A computer system includes a data storage device on the first data bus, a device on the second data bus, and a bridge device capable of storing multiple data transactions for delivery from the second data bus to the first data bus. The bridge device includes a first data storage buffer preassigned to one of the transactions held in the bridge, and a buffer management element that assigns, if necessary, a second data storage buffer to the data transaction when the data associated with the transaction overflows the first data storage buffer.

Abstract: Access to bus devices on a bus is granted in a computer system, with each bus device asserting a request signal to request the bus. A detector determines if a bus device is multi-threaded or single-threaded. An arbiter masks or does not mask the request signal of a retried bus device based on whether the bus device is a multi-threaded device. The arbiter masks the request signal of a retried bus device if it is a single-threaded device, but does not mask the request signal if the retried bus device is a multi-threaded device. The bus device request includes a delayed request transaction, and the bus includes a PCI bus.