Abstract: For an integrated circuit (IC) that retrieves data from a memory device external to the IC, a novel memory interface module that generates a sampling clock to the memory device and samples the retrieved data is described. The memory interface module adjusts the frequency of the sampling clock and selects a sampling time for sampling the retrieved data. The memory interface includes a training module that monitors a data pin of the memory device for transitions. The training module searches and records the earliest transition and the latest transition with respect to the period of the sampling clock. The memory interface module uses the earliest transition and the latest transition to determine an interval of data uncertainty (uncertainty interval) for the data pin. The memory interface module facilitates determining a new sampling time and a new sampling clock frequency based on the uncertainty intervals.

Abstract: A system includes a main memory device which stores information for translating a virtual address into a physical address in response to one of a plurality of processing devices. A memory control/interface device is coupled to the main memory device. The memory control/interface device, which may access the information stored in the main memory device, has a separate translation look-aside buffer for each processing device. Each translation look-aside buffer can buffer the information for use in translating in response to the respective processing device.

Abstract: A system and method are provided for optimizing the translation of virtual addresses into physical addresses for a graphics address remapping table (GART). In the system and method, a translation look-aside buffer cache has a plurality of translation look-aside buffer entries. Each translation look-aside buffer entry is operable to buffer information which may be accessed for use in translating a virtual address into a physical address. A least recently used pointer circuit is operable to point to a translation look-aside buffer entry buffering information least recently used in the translation look-aside buffer cache. During operation, updates to the least recently used pointer circuit may be pipelined with corresponding accesses to the translation look-aside buffer cache.

Abstract: A control sequencer circuit issues a sequence of commands to logic devices synchronized to a response by a slave device to a command by a master device. In one instance, the control sequencer circuit is statically adjusted to the timing semantics of the acknowledgment signal of the slave device. The control sequencer circuit includes an event detector, a static sliding window, and a sequencer stage. The event detector receives an acknowledgment signal and a requester ID from a slave device and determines if it is the proper recipient. The static sliding window synchronizes the command sequence to the response by the slave device and adjusts for the timing semantics of the acknowledgment signal of the slave device. The control sequencer stage successively outputs active signals at each clock cycle, thereby generating the command sequence.

Abstract: A memory controller for a computer memory which decodes memory requests into individual primitive memory operations which are then queued into separate operation queues. The operation queues independently issue their queued primitive memory operations to the memory in order to initiate the memory request. The operation queues monitor and adhere to timing and ordering dependencies between the primitive memory operations that are queued and those that have already been transmitted to the memory. Once a primitive memory operation is transmitted to the memory, it is dequeued from its respective operation queue. A control queue monitors the progress of the primitive memory operations transmitted to the memory, completes the initiated memory request and provides timing and ordering dependency data to the operation queues.

Abstract: A control queue for predicting, tracking and completing memory requests initiated by a memory controller in a computer memory. The control queue is loaded with the cycle by cycle control data necessary to complete the memory request. The control queue shifts its contents from one entry to the next on every clock cycle to the bottom entry of the queue. The control data from the bottom entry is used to generate signals and data to control the operation of the data path for the current clock cycle. The control queue also tracks and provides operational and timing dependency data to the memory controller so that operations can be initiated properly.

Abstract: A memory controller for a dynamic random access memory which pre-charges active banks in a particular chip select when an eight quadword access is made to another bank within that same chip select. When the memory controller detects an eight quadword access which is a page hit or page miss within the same chip select, the memory controller will look for any other active banks on that chip select. If there is another active bank other than the bank being accessed by the eight quadword access, the memory controller will attempt to transmit a pre-charge operation to that bank in the clock cycle immediately following the acceptance of the eight quadword access.

Abstract: A memory controller for a computer memory which decodes memory requests into individual primitive memory operations which are then queued into separate operation queues. The operation queues independently issue their queued primitive memory operations to the memory in order to initiate the memory request. The operation queues monitor and adhere to timing and ordering dependencies between the primitive memory operations that are queued and those that have already been transmitted to the memory. Once a primitive memory operation is transmitted to the memory, it is dequeued from its respective operation queue. A control queue monitors the progress of the primitive memory operations transmitted to the memory, completes the initiated memory request and provides timing and ordering dependency data to the operation queues.

Abstract: A memory controller for a dynamic random access memory having counters for each chip select in the memory. The counters are incremented at a fixed interval. Programmable threshold values are provided which, when compared with the counters, indicate to the memory controller when a refresh should be opportunistically attempted and when a refresh is urgently required. The memory controller then either attempts to find an idle cycle to send the opportunistic refresh or blocks memory accesses to create a window for an urgently needed refresh. Once a refresh is sent to the memory, the appropriate counter is decremented accordingly.

Abstract: A memory controller for a dynamic random access memory having counters for each chip select in the memory. The counters are incremented at a fixed interval. Programmable threshold values are provided which, when compared with the counters, indicate to the memory controller when a refresh should be opportunistically attempted and when a refresh is urgently required. The memory controller then either attempts to find an idle cycle to send the opportunistic refresh or blocks memory accesses to create a window for an urgently needed refresh. Once a refresh is sent to the memory, the appropriate counter is decremented accordingly.