FAULT DETECTION

An apparatus has processing circuitry with at least two replicated computation blocks. Each computation block performs a particular calculation based on a respective input value to produce a respective output value to be used as a result of the calculation. The apparatus also has storage circuitry arranged on output paths of the computation blocks to store the output values of the computation blocks. The processing circuitry is operable in a fault detection mode in which the processing circuitry latches the output values of the computation blocks in the storage circuitry and presents, as the result of the calculations, the stored values. The processing circuitry also provides a first input value for a first computation block as an input value to one or more additional computation blocks of the at least two replicated computation blocks and compare the output values of the one or more additional computation blocks, when performing the calculation based on the first input value, with an output value of the first computation block when performing the calculation based on the first input value. If the processing circuitry detects a mismatch in the comparison, the processing circuitry determines that a fault exists in at least one of the computation blocks.