US Patent 7447955 Test apparatus and test method

There is provided a test apparatus for testing a memory-under-test for storing data strings to which an error correcting code has been added, having a logical comparator for comparing each data contained in the data string read out of the memory-under-test with an expected value generated in advance, a data error counting section for counting a number of data inconsistent with the expected value, a plurality of registers, provided corresponding to each of a plurality of classes, for storing an upper limit value of a number of errors contained in the data -under-test to be classified into the class, comparing sections for comparing each of the plurality of upper limit values stored in the plurality of registers with the counted value of the data error counting section and a classifying section for classifying the memory-under-test into the class corresponding to the register storing the upper limit value which is greater than the counted value.