Abstract: A SLDRAM System is provided with a plurality of in-circuit, calibratable memory modules and a memory controller for issuing unicast and multicast command packets to the memory modules. Command packets are transmitted over a unidirectional command link that includes a complementary pair of command clock lines, a command FLAG line and a plurality of noncomplemented command bit lines. Each of the command clock lines, command bit lines and the FLAG line is a SLIO transmission line. Data transfer operations are carried out in response to the command packets over one or more bidirectional data links that each includes two complementary pairs of data clock lines, and a plurality of noncomplemented data bit lines. Each of the data clock lines and the data bit lines is a SLIO transmission line. Each SLIO transmission line is single-end terminated and preferably tapped into by way of stub resistors.

Abstract: A method and apparatus for optimizing the efficiency of a data bus for a memory device. Extra latency is added between the time a memory controller issues a write instruction and the time the data is transferred on the data bus. This additional latency is optimized to reduce the number of idle time slots on the data bus when switching between a read instruction and a write instruction. Programmable registers are provided for adjusting the amount of latency.

Abstract: A SLDRAM System is provided with a plurality of in-circuit, calibratable memory modules and a memory controller for issuing unicast and multicast command packets to the memory modules. Command packets are transmitted over a unidirectional command link that includes a complementary pair of command clock lines, a command FLAG line and a plurality of noncomplemented command bit lines. Each of the command clock lines, command bit lines and the FLAG line is a SLIO transmission line. Data transfer operations are carried out in response to the command packets over one or more bidirectional data links that each includes two complementary pairs of data clock lines, and a plurality of noncomplemented data bit lines. Each of the data clock lines and the data bit lines is a SLIO transmission line. Each SLIO transmission line is single-end terminated and preferably tapped into by way of stub resistors.

Abstract: Method and apparatus for implementing a variable length pipeline in a packet-driven memory control system, including a command front end and one or more parallel command sequencers. The command front end decodes an external command packet into an internal command and issues it to a selected one of the command sequencers. The command has associated therewith a desired latency value. A first group of one or more memory control steps for the given command is performed by the command front end if the desired latency value is less than a threshold latency value, or by the selected command sequencer if the desired latency value is greater than or equal to the threshold latency value. The remainder of the memory control steps required for the command are performed by the selected command sequencer. If the first control steps are to be performed by the selected command sequencer, then depending on the desired latency value, the command sequencer further may insert one or more wait states before doing so.

Abstract: A contention-free transition-based signaling scheme in which a plurality of controlling units and one or more controlled units are connected to a shared bus line, which is also connected to a bus holder cell. Each of the controlling units includes an output circuit that asserts a control signal on the bus line by synchronously asserting a logic level transition on the bus line, and each of the controlled units includes an input circuit that detects assertion of the control signal by detecting that a logic level transition has occurred on the bus line. The synchronous nature of the scheme avoids the possibility of contention because all of the controlling units that intend to assert a logic level transition in a given clock cycle sampled the current logic level at the same time (within the same prior clock cycle). They therefore all agree on the current logic level and will all assert the same opposite logic level when asserting their logic level transition.

Abstract: Method and apparatus for implementing a variable length pipeline in a packet-driven memory control system, including a command front end and one or more parallel command sequencers. The command front end decodes an external command packet into an internal command and issues it to a selected one of the command sequencers. The command has associated therewith a desired latency value. A first group of one or more memory control steps for the given command is performed by the command front end if the desired latency value is less than a threshold latency value, or by the selected command sequencer if the desired latency value is greater than or equal to the threshold latency value. The remainder of the memory control steps required for the command are performed by the selected command sequencer. If the first control steps are to be performed by the selected command sequencer, then depending on the desired latency value, the command sequencer further may insert one or more wait states before doing so.

Abstract: A memory circuit with glitch-less transfer of timing information. In one embodiment, the invention is a memory circuit including a controller, multiple loads, a command link communicatively coupling the controller and the loads and a data link. The data link includes multiple data clocks and communicatively couples the controller and the multiple loads. In another embodiment, the invention transfers data between a memory controller and a RAM by coupling the controller and the RAM using a data bus and multiple clock lines. The invention transfers a read/write command from the controller to the RAM and then transfers data associated with the read/write command, clocking the data using one of the clock lines.

Abstract: A computer memory device featuring a high-bandwidth memory interface to transfer information between a controller and the memory cells of a memory modules. Bifurcated communication buses is provided to take advantage of the interface. One of the bifurcated communication busses is dedicated to data information transfer, dataLink, between the controller and the memory modules, with the remaining bus, commandLink, being dedicated to command/address information transfer therebetween. This facilitates communication between the controller and the memory modules using information packets, bifurcated into data packets and command/address packets. To that end, the interface circuitry includes encoded chip select techniques that employs slaveId comparison logic, a plurality of control registers and delay registers to regulate the synchronization of communication transfers over the commandLink and the dataLink, as well as a queue register in which the packets are temporarily stored.

Abstract: A method and apparatus for optimizing the efficiency of a data bus for a memory device. Extra latency is added between the time a memory controller issues a write instruction and the time the data is transferred on the data bus. This additional latency is optimized to reduce the number of idle time slots on the data bus when switching between a read instruction and a write instruction. Programmable registers are provided for adjusting the amount of latency.