TEST DEVICE AND TEST METHOD

摘要

It is possible to effectively test a memory under test (hereinafter, referred to DUT) containing a data string having an error correction code. The test device compares each bit contained in the data string read from the DUT to an expectation value. The comparison result is stored as bit pass fail information indicating good/bad of each storage cell of the DUT in a first fail memory (hereinafter, referred to as FM). The storage device counts the number of bits which do not coincide with the expectation value for each page and judges whether the number of bits not coinciding with the expectation value satisfies the condition of the grade for each grade and page of the DUT. The judgment result is stored as page pass fail information indicating good/bad of each page for each grade in a second FM. If page pass fail information that a page containing a bit corresponding to a certain storage cell satisfies a certain grade condition is stored in the second FM, the test device modifies the bit pass fail information in the first FM to a value indicating that the storage fail is not bad and outputs it.