Abstract: One disclosed embodiment may comprise a design method for a dynamic circuit system. The method may include providing a design for a single stage network comprising a pull-down network that is configured to perform a desired logic function according to a plurality of inputs. The method may also include designing a multi-stage network that includes at least two stages, each of the at least two stages including a pull-down network that receives a respective portion of the plurality of inputs and each of the at least two stages cooperating to perform the desired logic function.

Abstract: In a preferred embodiment, the invention provides a circuit and method for improving the soft error rate in a dual-port read SRAM cell. A write-only transfer device is connected to a cross-coupled latch, a first wordline, and a first bitline. A first read-only transfer device is connected to a second bitline, a second wordline, and a first pull-down device. A second read-only transfer device is connected to the first bitline, the first wordline, and a second pull-down device. A clear memory transfer device is connected to the cross-coupled latch, a third bitline, and a third pull-down device. This configuration allows a reduction in the size of a dual-port SRAM cell with little or no reduction in the read access time of the cell. The reduction in size also reduces SER by reducing the cross-sectional, p/n junction area exposed to radiation.

Abstract: A system and method are disclosed which provide a cache structure that allows early access to the cache structure's data. A cache design is disclosed that, in response to receiving a memory access request, begins an access to a cache level's data before a determination has been made as to whether a true hit has been achieved for such cache level. That is, a cache design is disclosed that enables cache data to be speculatively accessed before a determination is made as to whether a memory address required to satisfy a received memory access request is truly present in the cache. In a preferred embodiment, the cache is implemented to make a determination as to whether a memory address required to satisfy a received memory access request is truly present in the cache structure (i.e., whether a “true” cache hit is achieved). Although, such a determination is not made before the cache data begins to be accessed.

Abstract: A system and method are disclosed which enable resolution of conflicts between memory access requests in a manner that allows for efficient usage of cache memory. In one embodiment, a circuit comprises a cache memory structure comprising multiple banks, and a plurality of access ports communicatively coupled to such cache memory structure. The circuit further comprises circuitry operable to determine a bank conflict for pending access requests for the cache memory structure, and circuitry operable to issue at least one access request to the cache memory structure out of the order in which it was requested, responsive to determination of a bank conflict.

Abstract: The present invention provides a precharge circuit that has a first precharged node, a second precharged node, and a latch device. The first precharged node is charged to a high value during a precharge state. In response to a transition from the precharge state to an evaluate state, it either discharges to a low value or remains charged at its high value. The second precharged node has a value in the evaluate state that is based on the value of the first precharged node upon the circuit transitioning to the evaluate state. The latch device is connected to the second precharged node for latching this value in the evaluate state. With the latching device, this value is not affected by the first precharged node once the circuit has sufficiently transitioned to the evaluate state.

Abstract: The inventive cache uses a queuing structure which provides out-of-order cache memory access support for multiple accesses, as well as support for managing bank conflicts and address conflicts. The inventive cache can support four data accesses that are hits per clocks, support one access that misses the L1 cache every clock, and support one instruction access every clock. The responses are interspersed in the pipeline, so that conflicts in the queue are minimized. Non-conflicting accesses are not inhibited, however, conflicting accesses are held up until the conflict clears. The inventive cache provides out-of-order support after the retirement stage of a pipeline.

Abstract: A system and method are disclosed which provide a built-in self test (BIST) for a content addressable memory (CAM) structure. In a preferred embodiment, an integrated circuit (chip) comprises a CAM structure that is accessible by a processor to satisfy memory access requests and a BIST implemented within such chip, which enables testing the integrity of the CAM structure. Such a preferred embodiment comprises a BIST that enables testing the integrity of the CAM structure that does not require circuitry for reading memory data out of the CAM structure. A preferred embodiment can also be utilized for testing a random access memory structure. In a preferred embodiment, a CAM BIST comprises logic capable of generating test values (e.g., a test pattern), a shift register that temporarily stores the test values generated by the logic, and compare circuitry that determines whether a test value matches an entry within the CAM structure.

Abstract: The inventive cache manages address conflicts and maintains program order without using a store buffer. The cache utilizes an issue algorithm to insure that accesses issued in the same clock are actually issued in an order that is consistent with program order. This is enabled by performing address comparisons prior to insertion of the accesses into the queue. Additionally, when accesses are separated by one or more clocks, address comparisons are performed, and accesses that would get data from the cache memory array before a prior update has actually updated the cache memory in the array are canceled. This provides a guarantee that program order is maintained, as an access is not allowed to complete until it is assured that the most recent data will be received upon access of the array.

Abstract: A self-timed translation lookaside buffer (TLB) is disclosed that utilizes a two-level match scheme to trigger the evaluation of whether a match is achieved for a received virtual address within the TLB. The first level is referred to as the local match, and the second level is referred to as the global match. An entry of a TLB comprises groups of bits, with each group coupled to a separate local match line. Each of the local match lines of an entry is coupled to a global match line, which is initially set to a high voltage level and discharges to a low voltage level if any of the local match lines indicate a mismatch for their respective group. Accordingly, when the global match lines are evaluated, if the global match line has a high voltage level it indicates that the associated TLB entry matches the virtual address, otherwise the global match line indicates a mismatch for the entry. Multiple global match lines are evaluated to trigger a memory access for a matching entry.

Abstract: The inventive cache processes multiple access requests simultaneously by using separate queuing structures for data and instructions. The inventive cache uses ordering mechanisms that guarantee program order when there are address conflicts and architectural ordering requirements. The queuing structures are snoopable by other processors of a multiprocessor system. The inventive cache has a tag access bypass around the queuing structures, to allow for speculative checking by other levels of cache and for lower latency if the queues are empty. The inventive cache allows for at least four accesses to be processed simultaneously. The results of the access can be sent to multiple consumers. The multiported nature of the inventive cache allows for a very high bandwidth to be processed through this cache with a low latency.

Abstract: A system and method are disclosed which provide a cache structure that allows early access to the cache structure's data. A cache design is disclosed that, in response to receiving a memory access request, begins an access to a cache level's data before a determination has been made as to whether a true hit has been achieved for such cache level. That is, a cache design is disclosed that enables cache data to be speculatively accessed before a determination is made as to whether a memory address required to satisfy a received memory access request is truly present in the cache. In a preferred embodiment, the cache is implemented to make a determination as to whether a memory address required to satisfy a received memory access request is truly present in the cache structure (i.e., whether a “true” cache hit is achieved). Although, such a determination is not made before the cache data begins to be accessed.

Abstract: The present invention provides a precharge circuit that has a first precharged node, a second precharged node, and a latch device. The first precharged node is charged to a high value during a precharge state. In response to a transition from the precharge state to an evaluate state, it either discharges to a low value or remains charged at its high value. The second precharged node has a value in the evaluate state that is based on the value of the first precharged node upon the circuit transitioning to the evaluate state. The latch device is connected to the second precharged node for latching this value in the evaluate state. With the latching device, this value is not affected by the first precharged node once the circuit has sufficiently transitioned to the evaluate state.

Abstract: A cache with a translation lookaside buffer (TLB) that reduces the time required for retrieval of a physical address from the TLB when accessing the cache in a system that supports variable page sizing. The TLB includes a content addressable memory (CAM) containing the virtual page numbers corresponding to pages in the cache and a random access memory (RAM) storing the physical page numbers of the pages corresponding to the virtual page numbers in the CAM. The physical page number RAM stores a page mask along with the physical page numbers, and includes local multiplexers which perform virtual address bypassing of the physical page number when the page has been masked.

Abstract: A multi-level cache structure and associated method of operating the cache structure are disclosed. The cache structure uses a queue for holding address information for a plurality of memory access requests as a plurality of entries. The queue includes issuing logic for determining which entries should be issued. The issuing logic further comprises find first logic for determining which entries meet a predetermined criteria and selecting a plurality of those entries as issuing entries. The issuing logic also comprises lost logic that delays the issuing of a selected entry for a predetermined time period based upon a delay criteria. The delay criteria may, for example, comprise a conflict between issuing resources, such as ports. Thus, in response to an issuing entry being oversubscribed, the issuing of such entry may be delayed for a predetermined time period (e.g., one clock cycle) to allow the resource conflict to clear.

Abstract: The present invention provides a precharge circuit that has a first precharged node, a second precharged node, and a latch device. The first precharged node is charged to a high value during a precharge state. In response to a transition from the precharge state to an evaluate state, it either discharges to a low value or remains charged at its high value. The second precharged node has a value in the evaluate state that is based on the value of the first precharged node upon the circuit transitioning to the evaluate state. The latch device is connected to the second precharged node for latching this value in the evaluate state. With the latching device, this value is not affected by the first precharged node once the circuit has sufficiently transitioned to the evaluate state.

Abstract: A system and method are provided which enable a data carrier, such as a BIT line, to be held to a desired value while performing a memory access (e.g., a read or write operation) of SRAM in an efficient manner. In a preferred embodiment, cross-coupled PFETs are implemented to hold the BIT line to a desired value during a memory access of SRAM. As a result, a preferred embodiment enables a BIT line to transition from a high voltage value to a low voltage value free from conflict. That is, in a preferred embodiment, a holder PFET is not attempting to hold the BIT line high, while the SRAM or outside source (e.g., a “writing source”) is attempting to drive the BIT line to a low voltage value. Also, in a preferred embodiment, the BIT and NBIT lines (i.e., a complementary data carrier) can be driven to “true” low and “true” high voltage values.

Abstract: A system and method are disclosed which provide a register structure enabling a dual-ended write thereto with a minimum amount of high-level metal tracks and components, thereby minimizing the amount of surface area required for such register structure. A data carrier (e.g., a BIT line) is utilized to carry a data value desired to be written from a port to a memory cell of a register structure. Such a data carrier may be implemented as a high-level metal track that spans multiple register structures to enable a port the capability of writing to such multiple register structures. Also, a line for triggering a write operation for a port (e.g., a WORD line) is implemented, and such a triggering line may be implemented as a high-level metal track. A preferred embodiment provides a register structure that includes a dual-ended write mechanism. In a preferred embodiment, a complementary data carrier for a port is generated locally within a register structure.

Abstract: A system and method are disclosed which provide a pulse write mechanism to enable a port to write to a register structure without requiring a large amount of circuitry. One or more ports may be coupled to a register structure in a manner that enables the ports to write data to the register structure without requiring a large amount of circuitry. The ports may be coupled to the register structure in a manner that enables them the capability of reading data from the register structure without requiring additional circuitry beyond that required for a write operation. A preferred embodiment implements a single-ended write structure, wherein a data carrier (e.g., BIT line) is utilized to carry a data value desired to be written for a port. A preferred embodiment comprises a write pulse mechanism, such as a NFET, capable of setting the memory cell to an initial value before performing a write thereto.

Abstract: The present invention integrates a WWTM circuit with the write driver circuitry, which is an inherent part of any conventional SRAM design. Thus, a circuit for writing data into and weak write testing a memory cell is provided. In one embodiment, the circuit comprises a write driver that has an output for applying a write or a weak write output signal at the memory cell. The write driver has first and second selectable operating modes. In the first mode, the write driver is set to apply a weak write output signal from the output for performing a weak write test on the cell. In the second mode, the write driver is set to apply a normal write output signal that is sufficiently strong for writing a data value into the cell when it is healthy.