An apparatus comprises a plurality of redundant processing units to perform data processing redundantly in lockstep; common mode fault detection circuitry to detect an event indicative of a potential common mode fault affecting each of the plurality of redundant processing units; a memory shared between the plurality of redundant processing units; and memory checking circuitry to perform a memory scanning operation to scan at least part of the memory for errors; in which the memory checking circuitry performs the memory scanning operation in response to a common mode fault signal generated by the common mode fault detection circuitry indicating that the event indicative of a potential common mode fault has been detected.

Lockstep comparators and related methods are described. An example apparatus includes self-test logic circuitry having first outputs, and comparator logic including selection logic having first inputs and second outputs, ones of the first inputs coupled to the first outputs, first detection logic having second inputs and third outputs, the second inputs coupled to the second outputs, second detection logic having third inputs and fourth outputs, the third inputs coupled to the third outputs, latch logic having fifth inputs and fifth outputs, the third output and the fourth output coupled to the fifth inputs, and error detection logic having sixth inputs coupled to the fifth inputs.

An electronic computing system preserves a pre-error state of a processing unit by receiving a first stream of inputs; buffering the first stream of inputs to generate a buffered stream of inputs identical to the first stream of inputs; conveying the first stream to a primary instance of a first program; conveying the buffered stream to a secondary instance of the first program; executing the primary instance on the first stream in real time; executing the secondary instance on the buffered stream with a predefined time delay with respect to execution of the primary instance on the first stream; detecting an error state resulting from execution of the primary instance; and in response to detecting the error state, pausing the secondary instance and preserving a current state of the secondary instance, wherein the current state of the secondary instance corresponds to a pre-error state of the primary instance.

An embodiment device comprises a first processing unit configured to process an initial data line and deliver a first processed data line, a first delay unit coupled to the output of the first processing unit and configured to deliver a delayed first processed data line delayed by a first delay, a second delay unit configured to deliver the delayed initial data line delayed by a second delay, a second processing unit coupled to the output of the second delay unit and configured to process the delayed initial data line and deliver a delayed second processed data line, and a comparison unit configured to compare the contents of the delayed first and second processed data lines and deliver a non-authentication signal if the contents are not identical, the first and second delays being equal to a variable value.

Techniques including receiving a first control value, starting a timeout counter based on receiving the first control value, receiving a second control value, determining whether the second control value is received before the timeout counter expires, and based on the determination that the second control value is received before the timeout counter expires: determining whether the first control value is the same as the second control value, and loading the first control value into a set of control registers based on the determination that the first control value is the same as the second control value.

An exemplary fault-tolerant computing system comprises a secondary processor configured to execute in delayed lock step with a primary processor from a common program store, comparators in the store data and writeback paths to detect a fault based on comparing primary and secondary processor states, and a writeback path delay permitting aborting execution when a fault is detected, before writeback of invalid data. The secondary processor execution and the primary processor store data and writeback may be delayed a predetermined number of cycles, permitting fault detection before writing invalid data. Store data and writeback paths may include triple module redundancy configured to pass only majority data through the store data and writeback path delay stages. Some implementations may forward data from the store data path delay stages to the writeback stage or memory if the load data address matches the address of data in a store data path delay stage.

A method, executed by a computer, includes pairing a first core with a second core to form a first core group, wherein each core of the group has a plurality of functional units, transferring instructions received by the first core to the second core for execution via a first inter-core communication bus, and executing the instructions on the second core. A computer system and computer program product corresponding to the above method are also disclosed herein.

A circuit includes a primary register region and a primary shadow register; a secondary register region and a secondary shadow register; and a safety controller having multiple states. The safety controller transitions to a first write state when a first write signal to write a first value to the primary register region is detected, and copies the first value written to the primary register region to the primary shadow register; transitions to a second write state when a second write signal to write a second value to the secondary register region is detected within a set amount of time of detection of the first write signal, and in the second write state, copies the second value written to the secondary register region to the secondary shadow register; transitions to a compare state to receive a comparison signal indicating whether the first value is the same as the second value; and transitions to an update state when the first value is the same as the second value.

A computing apparatus includes a transaction-record memory and a comparator. The transaction-record memory is to receive and store one or more sequences of transaction records, each transaction record including a unique transaction ID and a transaction payload. The comparator is to compare the payloads of transaction records having the same transaction ID, and to initiate a responsive action in response to a discrepancy between the compared transaction payloads.

An information processing system includes: a first system that includes a group of arithmetic units, a controller, and an external device; and a second system configured to execute calculation which is the same as calculation executed in the first system and compare calculation results to each other, wherein the controller is configured to: stop a plurality of arithmetic units when it is detected that an output request to the external device is output from one or more arithmetic units among the plurality of arithmetic units that execute first calculation in the group of arithmetic units, the plurality of arithmetic units including one or more arithmetic units that does not output the output request, transmit first comparison target data including a value output in response to the output request to the second system, and instruct the stopped one or more arithmetic units to execute second calculation.