Patent attributes
A test apparatus compares bits included in a data sequence read from a DUT with expectation values. Comparison results are stored in a first failure memory (FM) as bit information indicating whether storage cells of the DUT are non-defective. The storage device counts the number of bits not matching the expectation values for each page, and judges for each grade/page of the DUT whether the number of bits not matching the expectation values meets the condition of that grade. Judgment results are stored in a second FM as page information indicating whether each page is non-defective for each grade. If page information of a page including a bit corresponding to a storage cell indicating that this page meets the condition of any grade is stored in the second FM, the apparatus outputs the bit information in the first FM, by changing it to a value indicating that storage cell is as non-defective.
