To duplicate a test is one of the most robust methods that exists for generic soft error detection. A drawback is that no strict assumption on the cause of the errors (EMI, ESD etc.), nor on the type of errors to expect (errors affecting the control flow, errors affecting data etc.) can be made. Erroneous bit-changes in data-bytes while stored in memory, cache, register, or transmitted on a bus are known. These data-bytes could be operation codes (instructions), memory addresses, or data. Thus, this method is able to detect a wide range of faults, and is not limited to a specific fault model. Using this method, memory increases about four times, and execution time is about 2.5 times as long as the same program without test duplication. Source listing to the right shows a sample implementation of the duplication of test conditions.