A system and approach that may connect communication modules together in a daisy chain fashion as an expansion bus. A communication module may be connected with a data bus and a voltage bus to a baseboard having a controller. The communication module may have a multi-port universal serial bus hub connected to the data bus from the expansion connector, an electronic device connected to the hub and the voltage regulator. Another communication module having a similar structure as the first communication module may be connected to the first communication module via a data bus between the multiport hub of the first expansion module and a universal serial bus hub of the other communication module, and may have a voltage bus connected to the voltage bus of the first communication module. More communication modules may be connected in a daisy chain or serial fashion to a preceding module, and so on.

A memory system of a high-speed operation can be realized by reducing an influence of reflection signals etc. caused by branching and impedance mismatching in various wirings between a memory controller and a memory module, and an influence due to transmission delays of data, command/address, and clocks in the memory module. To this end, a memory system comprises a memory controller and a memory module mounted with DRAMs. A buffer is mounted on the memory module. The buffer and the memory controller are connected to each other via data wiring, command/address wiring, and clock wiring. The DRAMs and the buffer on the memory module are connected to each other via internal data wiring, internal command/address wiring, and internal cock wiring. The data wiring, the command/address wiring, and the clock wiring may be connected to buffers of other memory modules in cascade. Between the DRAMs and the buffer on the memory module, high-speed data transmission is implemented using data phase signals synchronous with clocks.

To accommodate multiple masters over bus architectures supporting a single master device, a mechanism is provided for an inactive master device to assert an in-band IRQ. A current master then polls the other inactive master devices over a shared data bus to ascertain which inactive master device is asserting the IRQ. Upon identifying the asserting inactive master device, the current master device grants control of the data bus to the new master device, thereby making the inactive master the new active master device.

A computing system including multiple integrated circuit memory devices is described. One or more command and address buses are connected to the memory devices to transmit command and address signals to each memory device. Multiple clock lines are connected to the multiple memory devices in a tree structure to transmit multiple clock signals to these memory devices. The tree structure allows each distributed clock signal to be individually trained such that the multiple clock signals provide each memory device with a clock signal that is temporally aligned with the command and address signals as received by that memory device.

A memory module is operatable in a memory system with a memory controller. The memory module comprises a module control device to receive command signals from the memory controller and to output module C/A signals and data buffer control signals. The module C/A signals are provided to memory devices organized in groups, each group including at least one memory device, while the data buffer control signals are provided to a plurality of buffer circuits to control data paths in the buffer circuits, a respective buffer circuit corresponding to a respective group of memory devices. The plurality of buffer circuits are distributed across a surface of the memory module such that each data buffer control signal arrives at the plurality of buffer circuits at different points in time. The plurality of buffer circuits include clock regeneration circuits to regenerate a clock signal received from the module control device and to provide regenerated clock signals to respective groups of memory devices.

A method for operating a data interface circuit whereby calibration adjustments for data bit capture are made without disturbing normal system operation includes initially establishing, using a first calibration method where a data bit pattern received by the data interface circuit is predictable, an optimal sampling point for sampling data bits received by the data interface circuit, and during a normal system operation and without disturbing the normal system operation, performing a second calibration method where the data bit pattern received by the data interface circuit is unpredictable. The second calibration method determines an amount of a timing drift for received data bit edge transitions and adjusts the optimal timing point determined by the first calibration method to create a revised optimal timing point. The second calibration method samples fringe timing points associated with the transition edges of a data bit.

Memory devices and a memory controller that controls such memory devices. Multiple memory devices receive commands and addresses on a command/address (C/A) bus that is relayed point-to-point by each memory device. Data is received and sent from these devices to/from a memory controller in a point-to-point configuration by adjusting the width of each individual data bus coupled between the individual memory devices and the memory controller. Along with the C/A bus are clock signals that are regenerated by each memory device and relayed. The memory controller and memory devices may be packaged on a single substrate using package-on-package technology. Using package-on-package technology allows the relayed C/A signals to connect from memory device to memory device using wire bonding. Wirebond connections provide a short, high-performance signaling environment for the chip-to-chip relaying of the C/A signals and clocks from one memory device to the next in the daisy-chain.

A system and approach that may connect communication modules together in a daisy chain fashion as an expansion bus. A communication module may be connected with a data bus and a voltage bus to a baseboard having a controller. The communication module may have a multi-port universal serial bus hub connected to the data bus from the expansion connector, an electronic device connected to the hub and the voltage regulator. Another communication module having a similar structure as the first communication module may be connected to the first communication module via a data bus between the multiport hub of the first expansion module and a universal serial bus hub of the other communication module, and may have a voltage bus connected to the voltage bus of the first communication module. More communication modules may be connected in a daisy chain or serial fashion to a preceding module, and so on in a similar manner.

In some examples, a management controller is to dynamically vary a parameter that controls an operational characteristic of a bus when transferring different portions of information from a memory over the bus during a process of an electronic device in which a cryptographic operation is performed. The different portions of the information from the memory are to be transferred over the bus with different operational characteristics of the bus.

A computing system including multiple integrated circuit memory devices is described. One or more command and address buses are connected to the memory devices to transmit command and address signals to each memory device. Multiple clock lines are connected to the multiple memory devices in a tree structure to transmit multiple clock signals to these memory devices. The tree structure allows each distributed clock signal to be individually trained such that the multiple clock signals provide each memory device with a clock signal that is temporally aligned with the command and address signals as received by that memory device.