Abstract: A memory buffer, memory system and method for power-on initialization and test for a cascade interconnect memory system. The memory buffer includes a bus interface to links in a high-speed channel for communicating with a memory controller via a direct connection or via a cascade interconnection through an other memory buffer. The interface is operable in a SBC mode and a high-speed mode. The memory buffer also includes a field service interface (FSI) slave for receiving FSI signals from a FSI master. In addition, the memory buffer includes logic for executing a power-on and initialization training sequence initiated by the memory controller.

Abstract: Systems and methods for providing automatic read flow control in a cascade interconnect memory system. A hub device includes an interface to a channel in a cascade interconnect memory system for connecting the hub device to an upstream hub device or a memory controller. The channel includes an upstream bus and a downstream bus. The hub device also includes read data flow control logic for determining when to transmit data on the upstream bus. The determining is responsive to an order of commands received on the downstream bus and to current traffic on the upstream bus.

Abstract: A memory module including a plurality of memory channel connectors for communicating with a memory controller via a plurality of high-speed channels. The memory module also includes a plurality of memory devices arranged in one or more ranks, and a plurality of independently operable hub devices. Each hub device includes an interface for receiving signals from and driving signals to the memory controller on one of the high-speed channels via one or more of the memory channel connectors. Each hub device also includes a plurality of independently operable ports to communicate with all or a subset of the ranks of memory devices.

Abstract: A communication interface device, system, method, and design structure for bit shadowing in a memory system are provided. The communication interface device includes shadow selection logic to select a driver bit position as a shadowed driver value, and line drivers to transmit data for the selected driver bit position and the shadowed driver value on separate link segments of a bus. The communication interface device also includes shadow compare logic to compare a selected received value with a shadowed received value from the bus and identify a miscompare in response to a mismatch of the compare, and shadow counters to count a rate of the miscompare relative to a bus error rate over a period of time. A defective link segment is identified in response to the rate of the miscompare within a predefined threshold of the bus error rate.

Abstract: Design structures embodied in machine readable medium are provided. Embodiments of the design structure include a memory system comprising: a memory controller; a memory bus terminator; a high speed memory bus that interconnects the memory controller, the memory bus terminator, and at least one memory module; and the at least one memory module, the memory module comprising at least one memory hub device, high speed random access memory served by the memory hub device, two bus signal ports, and a segment of the high speed memory bus fabricated on the memory module so as to interconnect the bus signal ports and the memory hub device, the high speed memory bus connected to the memory hub device by a negligible electrical stub.

Abstract: A memory system for providing a slow command decode over an untrained high-speed interface. The memory system includes a memory system having a memory interface device, an untrained high-speed interface, and a memory controller. The untrained high-speed interface is in communication with the memory interface device. The memory controller generates slow commands and transmits the slow commands to the memory interface device via the untrained high-speed interface. The slow commands operate at a first data rate that is slower than a second data rate utilized by the high-speed interface after it has been trained. The memory interface device receives the slow commands via the untrained high-speed interface, decodes the slow commands, and executes the slow commands.

Abstract: Memory systems are disclosed that include a memory controller; a memory bus terminator; a high speed memory bus that interconnects the memory controller, the memory bus terminator, and at least one memory module, where memory module includes a memory hub device, high speed random access memory served by the memory hub device, two bus signal ports, and a segment of the high speed memory bus fabricated on the memory module so as to interconnect the bus signal ports and the memory hub device, with the high speed memory bus connected to the memory hub device by a negligible electrical stub.

Abstract: A system and method for providing SDRAM mode register shadowing in a memory system. A system includes a memory interface device adapted for use in a memory system. The memory interface device includes an interface to one or more ranks of memory devices, and each memory device includes one or more types of mode registers. The memory interface device also includes an interface to a memory bus for receiving commands from a memory controller. The commands include a mode register set command specifying a new mode register setting for one or more ranks of memory devices and a mode register type. The memory interface device further includes a mode register shadow module to capture settings applied to the mode registers. The module includes a shadow register for each type of mode register and a shadow log for each type of mode register.

Abstract: A memory system including a first memory subsystem having a buffer device with a first port and a second port, one or more memory devices coupled to the buffer device via the second port, and a first two-on-one link for coupling to a memory controller for providing communication between the buffer device and the memory controller. The first two-on-one link is coupled to the first port of the buffer device. The first memory subsystem is configured to transfer data between at least one memory device of the one or more memory devices and the memory controller via the buffer device. The first two-on-one link includes up to two transceivers connected to a single link, with at least one of the up to two transceivers consisting of any one of two or more transmitters for transmitting signals or two or more receivers for receiving signals.

Abstract: A cascaded interconnect system for providing a service interface to a memory system. The cascaded interconnect system includes a master service interface module, a service interface bus, and one or more slave service interface modules. The master service interface module and the slave interface modules are cascade interconnected via the service interface bus. Each slave service interface module is in communication with a corresponding memory module for providing a service to the memory module.

Abstract: Systems and methods for providing a dynamic memory buffer bank policy. Embodiments include a hub device for selecting a bank page policy. The hub device includes an input command stream interface and a bank page policy module. The input command stream interface detects commands from a memory controller that are directed to one or more memory devices that are connected to the hub device. The bank page policy module independently analyzes the commands to determine access patterns to the memory devices and for dynamically selecting between an open bank page policy and a closed bank page policy for the memory devices based on the analysis.

Abstract: Systems and methods for providing dynamic memory pre-fetch. Embodiments include a hub device including an input command stream interface and an adaptive pre-fetch logical unit (APLU). The input command stream interface detects commands from a memory controller directed to one or more memory devices that are connected to the hub device. The APLU independently analyzes the commands to determine access patterns to the memory devices. The APLU also dynamically selects between enabling a pre-fetch function and disabling the pre-fetch function for the memory devices based on the results of the analysis.

Abstract: Systems and methods for providing distributed technology independent memory controllers. Systems include a computer memory system for storing and retrieving data. The system includes a memory bus, a main memory controller, one or more memory devices characterized by memory device protocols and signaling requirements, and one or more memory hub devices. The main memory controller is in communication with the memory bus for generating, receiving, and responding to memory access requests. The hub devices are in communication with the memory bus and with the memory devices for controlling the memory devices responsively to the memory access requests received from the main memory controller and for responding to the main memory controller with state or memory data.

Abstract: A cascaded interconnect system with one or more memory modules, a memory controller and a memory bus that utilizes periodic recalibration. The memory modules and the memory controller are directly interconnected by a packetized multi-transfer interface via the memory bus and provide scrambled data for use in the periodic recalibration.

Abstract: A memory system is provided that supports partial cache line write operations to a memory module to reduce write data traffic on a memory channel. The memory system comprises a memory hub device integrated in the memory module and a set of memory devices coupled to the memory hub device. The memory hub device comprises burst logic integrated in the memory hub device. The burst logic determines an amount of write data to be transmitted to the set of memory devices and generates a burst length field corresponding to the amount of write data. The memory hub also comprises a memory hub controller integrated in the memory hub device. The memory hub controller controls the amount of write data that is transmitted using the burst length field. The memory hub device transmits the amount of write data that is equal to or less than a conventional data burst amount.

Abstract: Systems and methods for providing distributed autonomous power management in a memory system. Embodiments include a memory system for storing and retrieving data for a processing system. The memory system includes a memory controller for receiving and responding to memory access requests, a memory bus in communication with the memory controller, a plurality of memory devices, and a control unit external to the memory controller. The memory devices are in communication with the memory controller via the memory bus, with one or more of the memory devices being associated with a group. The control unit autonomously manages power within and for the group of memory devices.

Abstract: A memory system is provided that provides memory system power reduction without reducing overall memory system performance. The memory system comprises a memory hub device integrated in a memory module. The memory hub device comprises a command queue that receives a memory access command from an memory controller via a memory channel at a first operating frequency. The memory system also comprises a memory hub controller integrated in the memory hub device. The memory hub controller reads the memory access command from the command queue at a second operating frequency. By receiving the memory access command at the first operating frequency and reading the memory access command at the second operating frequency an asynchronous boundary is implemented. Using the asynchronous boundary, the memory channel operates at a maximum designed operating bandwidth while the second operating frequency is independently decreased to reduce power being consumed by the set of memory devices.

Abstract: A memory system is provided that reduces latency by running a memory channel fully asynchronous from a memory device frequency. The memory system comprises a memory hub device integrated in a memory module. The memory hub device comprises a command queue that receives a memory access command from an external memory controller via a memory channel at a first operating frequency. The memory system also comprises a memory hub controller integrated in the memory hub device. The memory hub controller reads the memory access command from the command queue at a second operating frequency. By receiving the memory access command at the first operating frequency and reading the memory access command at the second operating frequency an asynchronous boundary is implemented. The first operating frequency is a maximum designed operating frequency of the memory channel and the first operating frequency is independent of the second operating frequency.

Abstract: A memory system is provided that increases the overall bandwidth of a memory channel by operating the memory channel at a independent frequency. The memory system comprises a memory hub device integrated in a memory module. The memory hub device comprises a command queue that receives a memory access command from an external memory controller via a memory channel at a first operating frequency. The memory system also comprises a memory hub controller integrated in the memory hub device. The memory hub controller reads the memory access command from the command queue at a second operating frequency. By receiving the memory access command at the first operating frequency and reading the memory access command at the second operating frequency an asynchronous boundary is implemented. Using the asynchronous boundary, the memory channel operates at a maximum designed operating bandwidth, which is independent of the second operating frequency.

Abstract: A memory system is provided that manages thermal conditions at a memory device level transparent to a memory controller. The memory systems comprises a memory hub device integrated in a memory module, a set of memory devices coupled to the memory hub device, and a first set of thermal sensors integrated in the set of memory devices. A thermal management control unit integrated in the memory hub device monitors a temperature of the set of memory devices sensed by the first set of thermal sensors. The memory hub device reduces a memory access rate to the set of memory devices in response to a predetermined thermal threshold being exceeded thereby reducing power used by the set of memory devices which in turn decreases the temperature of the set of memory devices.