Abstract: A memory hub includes an on-board diagnostic engine through which diagnostic testing and evaluation of the memory system can be performed. The memory hub includes a link interface for receiving memory requests for access to memory devices of the memory system and a memory device interface coupled to the memory devices for coupling memory requests to the memory devices. A memory hub diagnostic engine is coupled through a switch to the link interface and the memory device interface to perform diagnostic testing of the memory system. The diagnostic engine includes a maintenance port that provides access to results of the diagnostic testing and through which diagnostic testing commands can be received.

Abstract: A layout for simultaneously sub-accessible memory modules is disclosed. In one embodiment, a memory module includes a printed circuit board having a plurality of sectors, each sector being electrically isolated from the other sectors and having a multi-layer structure. At least one memory device is attached to each sector, the memory devices being organized into a plurality of memory ranks. A driver is attached to the printed circuit board and is operatively coupled to the memory ranks. The driver is adapted to be coupled to a memory interface of the computer system. Because the sectors are electrically-isolated from adjacent sectors, the memory ranks are either individually or simultaneously, or both individually and simultaneously accessible by the driver so that one or more memory devices on a particular sector may be accessed at one time.

Abstract: A memory module includes several memory devices coupled to a memory hub. The memory hub includes several link interfaces coupled to respective processors, several memory controller coupled to respective memory devices, a cross-bar switch coupling any of the link interfaces to any of the memory controllers, a write buffer and read cache for each memory device and a read synchronization module. The read synchronization module includes a write pointer, a read pointer and a buffer. The write pointer is incremented in response to the receipt of read data. The read pointer increments in response to coupling of the read data from the memory hub. A comparator compares the read pointer an the write pointer, and the comparison is used to adjust the memory timing.

Abstract: A method and system that dynamically adjusts link control parameters of a communications network. The communications network includes a transmitter coupled through a first data link to a receiver. The transmitter and receiver each have at least one associated link control parameter that affects the operation of that component. According to one method, data signals are transmitted over the first data link and the transmitted data signals are captured. The values of the captured data signals are compared to expected values for those signals, and the values of the link control parameters are adjusted to successfully capture the transmitted digital signals.

Abstract: A memory hub module includes a decoder that receives memory requests determines a memory request identifier associated with each memory request. A packet memory receives memory request identifiers and stores the memory request identifiers. A packet tracker receives remote memory responses and associates each remote memory response with a memory request identifier and removes the memory request identifier from the packet memory. A multiplexor receives remote memory responses and local memory responses. The multiplexor selects an output responsive to a control signal. Arbitration control logic is coupled to the multiplexor and the packet memory and develops the control signal to select a memory response for output.

Abstract: A memory hub and method for transmitting a read response on a data path of a memory hub interposed between a transmitting memory hub and a receiving memory hub. An arbitration packet including data indicative of a data path configuration for an associated read response is received at the memory hub. The arbitration packet is decoded, and the data path is configured in accordance with the data of the arbitration packet. The associated read response is received at the memory hub and the associated read response is coupled to the configured data path for transmitting the same to the receiving memory hub.

Abstract: A memory module includes a memory hub that monitors utilization of the memory module and directs devices of the memory module to a reduced power state when the module is not being used at a desired level. System utilization of the memory module is monitored by tracking system usage, manifested by read and write commands issued to the memory module, or by measuring temperature changes indicating a level of device activity beyond normal refresh activity. Alternatively, measured activity levels can be transmitted over a system bus to a centralized power management controller which, responsive to the activity level packets transmitted by remote memory modules, direct devices of those remote memory modules to a reduced power state. The centralized power management controller could be disposed on a master memory module or in a memory or system controller.

Abstract: A memory module includes several memory devices coupled to a memory hub. The memory hub includes several link interfaces coupled to respective processors, several memory controller coupled to respective memory devices, a cross-bar switch coupling any of the link interfaces to any of the memory controllers, a write buffer and read cache for each memory device and a read synchronization module. The read synchronization module includes a write pointer, a read pointer and a buffer. The write pointer is incremented in response to the receipt of read data. The read pointer increments in response to coupling of the read data from the memory hub. A comparator compares the read pointer an the write pointer, and the comparison is used to adjust the memory timing.

Abstract: A memory module includes a memory hub that monitors utilization of the memory module and directs devices of the memory module to a reduced power state when the module is not being used at a desired level. System utilization of the memory module is monitored by tracking system usage, manifested by read and write commands issued to the memory module, or by measuring temperature changes indicating a level of device activity beyond normal refresh activity. Alternatively, measured activity levels can be transmitted over a system bus to a centralized power management controller which, responsive to the activity level packets transmitted by remote memory modules, direct devices of those remote memory modules to a reduced power state. The centralized power management controller could be disposed on a master memory module or in a memory or system controller.

Abstract: A system memory includes a memory hub controller, a memory module accessible by the memory hub controller, and an expansion module having a processor circuit coupled to the memory module and also having access to the memory module. The memory hub controller is coupled to the memory hub through a first portion of a memory bus on which the memory requests from the memory hub controller and memory responses from the memory hub are coupled. A second portion of the memory bus couples the memory hub to the processor circuit and is used to couple memory requests from the processor circuit and memory responses provided by the memory hub to the processor circuit.

Abstract: A processor-based electronic system includes several memory modules arranged in first and second ranks. The memory modules in the first rank are directly accessed by any of several processors, and the memory modules in the second rank are accessed by the processors through the memory modules in the first rank. The data bandwidth between the processors and the memory modules in the second rank is varied by varying the number of memory modules in the first rank that are used to access the memory module in the second set. Each of the memory modules includes several memory devices coupled to a memory hub. The memory hub includes a memory controller coupled to each memory device, a link interface coupled to a respective processor or memory module, and a cross bar switch coupling any of the memory controllers to any of the link interfaces.

Abstract: A memory module includes a memory hub coupled to several memory devices. The memory hub is also coupled to receive a memory packet from a system controller containing a memory hint indicative of the subsequent operation of the memory devices. The memory module uses the hint to adjust the operation of the memory module, such as the number of pages to remain open or cache lines to be fetched.

Abstract: A layout for simultaneously sub-accessible memory modules is disclosed. In one embodiment, a memory module includes a printed circuit board having a plurality of sectors, each sector being electrically isolated from the other sectors and having a multi-layer structure. At least one memory device is attached to each sector, the memory devices being organized into a plurality of memory ranks. A driver is attached to the printed circuit board and is operatively coupled to the memory ranks. The driver is adapted to be coupled to a memory interface of the computer system. Because the sectors are electrically-isolated from adjacent sectors, the memory ranks are either individually or simultaneously, or both individually and simultaneously accessible by the driver so that one or more memory devices on a particular sector may be accessed at one time.

Abstract: A computer system and a method used to access data from a plurality of memory devices with a memory hub. The computer system includes a plurality of memory modules coupled to a memory hub controller. Each of the memory modules includes the memory hub and the plurality of memory devices. The memory hub includes a sequencer and a bypass circuit. When the memory hub is busy servicing one or more memory requests, the sequencer generates and couples the memory requests to the memory devices. When the memory hub is not busy servicing multiple memory requests, the bypass circuit generates and couples a portion of each the memory requests to the memory devices and the sequencer generates and couples the remaining portion of each of the memory requests to the memory devices.

Abstract: A memory module includes a memory hub coupled to several memory devices. The memory hub includes history logic that predicts on the basis of read memory requests which addresses in the memory devices from which date are likely to be subsequently read. The history logic applies prefetch suggestions corresponding to the predicted addresses to a memory sequencer, which uses the prefetch suggestions to generate prefetch requests that are coupled to the memory devices. Data read from the memory devices responsive to the prefetch suggestions are stored in a prefetch buffer. Tag logic stores prefetch addresses corresponding to addresses from which data have been prefetched. The tag logic compares the memory request addresses to the prefetch addresses to determine if the requested read data are stored in the prefetch buffer. If so, the requested data are read from the prefetch buffer. Otherwise, the requested data are read from the memory devices.

Abstract: A memory hub module includes a decoder that receives memory requests determines a memory request identifier associated with each memory request. A packet memory receives memory request identifiers and stores the memory request identifiers. A packet tracker receives remote memory responses and associates each remote memory response with a memory request identifier and removes the memory request identifier from the packet memory. A multiplexor receives remote memory responses and local memory responses. The multiplexor selects an output responsive to a control signal. Arbitration control logic is coupled to the multiplexor and the packet memory and develops the control signal to select a memory response for output.

Abstract: A memory hub and method for transmitting a read response on a data path of a memory hub interposed between a transmitting memory hub and a receiving memory hub. An arbitration packet including data indicative of a data path configuration for an associated read response is received at the memory hub. The arbitration packet is decoded, and the data path is configured in accordance with the data of the arbitration packet. The associated read response is received at the memory hub and the associated read response is coupled to the configured data path for transmitting the same to the receiving memory hub.

Abstract: A memory hub for a memory module having a DMA engine for performing DMA operations in system memory. The memory hub includes a link interface for receiving memory requests for access at least one of the memory devices of the system memory, and further including a memory device interface for coupling to the memory devices, the memory device interface coupling memory requests to the memory devices for access to at least one of the memory devices. A switch for selectively coupling the link interface and the memory device interface is further included in the memory hub. Additionally, a direct memory access (DMA) engine is coupled through the switch to the memory device interface to generate memory requests for access to at least one of the memory devices to perform DMA operations.

Abstract: A computer system includes a controller coupled to a plurality of memory modules each of which includes a memory hub and a plurality of memory devices divided into a plurality of ranks. The memory hub is operable to configure the memory module to simultaneously address any number of ranks to operate in a high bandwidth mode, a high memory depth mode, or any combination of such modes.

Abstract: A memory module includes a memory hub coupled to several memory devices. The memory hub includes at least one performance counter that tracks one or more system metrics—for example, page hit rate, number or percentage of prefetch hits, cache hit rate or percentage, read rate, number of read requests, write rate, number of write requests, rate or percentage of memory bus utilization, local hub request rate or number, and/or remote hub request rate or number.