Abstract: A latch is described that provides soft error rate protection with integrated scan capability and collision avoidance. The latch has a latch output node and a first, second, and third sublatches. Each sublatch has a respective input circuitry, output node, and feedback circuitry coupled to the output node for reinforcing an output signal of the sublatch. Each sublatch is operable to receive a data signal at its input circuitry and responsively generate a binary-state output signal on its output nodes. The first and second output nodes such that, if an output of the third sublatch changes, the first and second sublatches force the third sublatch to have a same output. This “forced” change reduces the soft error rate in the latch and the output signal of the latch output node is restored without the sublatches colliding.

Abstract: A system and method of selective row energization based on write data, with a selective row energization system including a storage array 102 having M rows 104 and N columns 106; an N-bit data word register 108; a uniform-detect circuit 110 responsive to a data word to generate a uniform word data bit having a first value when the data word is uniform; an M-bit uniform-detect register 112 having M uniform-detect latches 114, each being associated with one of the M rows 104 and storing the uniform word data bit for the data word stored in the associated M row 104; and an M-bit row driver device 116 responsive to the uniform word data bit for each of the M rows 104 to inhibit energization of the M rows 104 for which the uniform word data bit is the first value.

Abstract: A CAM system is disclosed in which requests for address translation are provided as input search data to a dynamic compare bitline generator. The dynamic compare bitline generator also receives a compare mask and applies the compare mask to associated input search data bits on a per bit basis. The mask contains information that specifies a selected page size and a selected logic mode that can be applied to a compare array in which the specified search is conducted. The compare array is coupled to a data array to which the compare array indicates a result of the search.

Abstract: A method, system and apparatus for detecting soft errors in non-dataflow circuits. In a preferred embodiment, input is received at a latch system. The latch system consists of two pairs of latches. The second pair of latches is parallel to the first pair of latches. Both pairs of latches capture the input. However, the second pair of latches captures the input later in time relative to the first pair of latches latch. The captured input is then transferred from the first latch in each pair of latches to the second latch in each pair of latches. A comparison is made of the input in the two second latches. If the input captured in the two second latches is not the same, then a message is sent to a recovery unit.

Abstract: Recovery circuits react to errors in a processor core by waiting for an error-free completion of any pending store-conditional instruction or a cache-inhibited load before ceasing to checkpoint or backup progress of a processor core. Recovery circuits remove the processor core from the logical configuration of the symmetric multiprocessor system, potentially reducing propagation of errors to other parts of the system. The processor core is reset and the checkpointed values may be restored to registers of the processor core. The core processor is allowed not just to resume execution just prior to the instructions that failed to execute correctly the first time, but is allowed to operate in a reduced execution mode for a preprogrammed number of groups. If the preprogrammed number of instruction groups execute without error, the processor core is allowed to resume normal execution.

Abstract: A method and apparatus are provided for dispatch group checkpointing in a microprocessor, including provisions for handling partially completed dispatch groups and instructions which modify system coherent state prior to completion. An instruction checkpoint retry mechanism is implemented to recover from soft errors in logic. The processor is able to dispatch fixed point unit (FXU), load/store unit (LSU), and floating point unit (FPU) or vector multimedia extension (VMX) instructions on the same cycle. Store data is written to a store queue when a store instruction finishes executing. The data is held in the store queue until the store instruction is checkpointed, at which point it can be released to the coherently shared level 2 (L2) cache.

Abstract: A method, computer program product and system for testing stuck-at-faults. A first register may be loaded with a first value where the first value may be written into each entry in a memory array. A second register may be loaded with a second value. A third register may be loaded with either the second value or a third value. The second and third values are pre-selected to test selector circuits for stuck-at-faults with a pattern where the pattern includes a set of bits to be inputted to selector circuits and a set of bits to be stored in the memory cells. A value stored in the n-most significant bits in both the second and third registers may be predecoded to produce a predecode value. The predecode value may be compared with the value stored in the n-most significant bits in an entry in the memory array to determine a stuck-at-fault.

Abstract: A dynamic-static logical control element for signaling an interval between the end of a control signal and a logical evaluation provides a compact circuit for blocking the indication of a non-evaluated state of a dynamic logic gate until a control signal has ended. The control signal is connected to a precharge input of the control element and a summing node is connected to one or more evaluation trees and to the control element output via an inverter. The inverter is connected to an override circuit that forces the output of the control element to a state opposite the precharge state until the control signal has ended. The output of the control element then assumes a state corresponding to the precharge state until an evaluation occurs. The control element output thus produces a window signal indicating the interval between the end of the control signal and the evaluation.

Abstract: A register file apparatus and method incorporating read-after-write blocking using detection cells provides improved read access times in high performance register files. One or more detection cells identical to the register file cells and located in the register file array are used to control the read operation in the register file by configuring the detection cells to either alternate value at each write or change to a particular value after a write and then detecting when the write has completed by detecting the state change of an active detection cell. The state change detection can be used to delay the leading edge of a read strobe or may be used in the access control logic to delay generation of a next read strobe. The register file thus provides a scalable design that does not have to be tuned for each application and that tracks over voltage and clock skew variation.

Abstract: A register file is often used within integrated circuitry to temporarily hold data. Sometimes this data needs to be retained within the register file for a period of time, such as when there is a stall operation. Conventional register files have utilized a hold multiplexor to perform such a stall operation. The multiplexor however inserts a delay that is undesirable in high performance integrated circuitry. The multiplexor is replaced with a tri-state inverter coupled to the global bit line of the register file, which minimizes this additional delay from the register file data access time.

Abstract: A bit-read apparatus includes a first decoder and N multiplexers, each having Q output nodes and Q pull-ups coupled thereto. Respective multiplexers have M selectors coupled to N×M respective select lines and register-file cells. The selectors are in Q groups coupled to respective output nodes. Each multiplexer has a logic gate with inputs coupled to respective multiplexer output nodes. A second decoder is coupled to an N+1th multiplexer having R output nodes and R pull-ups coupled thereto. The N+1th multiplexer also has N selectors, coupled to respective select lines of the second decoder and respective output logic gates of the N multiplexers. The N selectors are in R groups coupled to the R nodes. An output logic gate for N+1th multiplexer has R inputs coupled respectively to the R nodes. Each pull-up of the multiplexers drives its respective multiplexer output node responsive to an address-bit signal.

Abstract: A register-file bit read apparatus includes a decoder operable to receive a number of address-bit signals and responsively assert a select signal on one of M select lines. Each select line corresponds to a respective one of M register-file cells. The apparatus also includes a multiplexer having Q output nodes and M selectors. Each selector is coupled to one of the select lines and that select line's corresponding register-file cell. The selectors are in Q groups, each coupled to a respective one of the multiplexer's output nodes. The apparatus also includes an output logic gate having Q inputs, coupled to respective ones of the multiplexer output nodes. The multiplexer includes Q pull-ups, each of which is coupled to a respective one of the multiplexer output nodes and is operable to drive its multiplexer output node responsive to one of the address-bit signals.

Abstract: A method, computer program product and system for testing stuck-at-faults. A first register may be loaded with a first value where the first value may be written into each entry in a memory array. A second register may be loaded with a second value. A third register may be loaded with either the second value or a third value. The second and third values are pre-selected to test selector circuits for stuck-at-faults with a pattern where the pattern includes a set of bits to be inputted to selector circuits and a set of bits to be stored in the memory cells. A value stored in the n-most significant bits in both the second and third registers may be predecoded to produce a predecode value. The predecode value may be compared with the value stored in the n-most significant bits in an entry in the memory array to determine a stuck-at-fault.