Patent ID: 7428662
Filing Date: 2008-09-23
Classification: G11C

Abstract:
1. A test method for testing a data store comprising: reading serially from the data store a plurality of test data in a test data sequence; and comparing the test data with reference nominal data that is written in a reference data register by an external test unit that is external to the data store in order to produce a compressed indicator data item, wherein the test data sequence is produced in a test data generator in an external test unit, and the test data in the test data sequence which have been read are written serially in a test data register in a test data compression circuit and are compared by logic gates bit by bit with reference nominal data written in a reference data register in the test data compression circuit in an initialization mode of operation; wherein a logic comparison circuit logically combines the outputs of the logic gates to form the compressed indicator data item, which indicates whether at least one data error has occurred in the test data sequence and wherein the compressed indicator data item is sent from the data store to the external test unit via an indicator data bus connecting the data store and the external test unit, and wherein the test data sequence is written to a memory cell array in the data store via a data line in a data bus, with the test data sequence written subsequently being read from the memory cell array in the data store via a data line in the data bus and being compressed by a test data compression circuit integrated in the data store on the basis of a compression factor (K) to form an indicator data item which is sent from the data store to the external test unit via an indicator data line in an indicator data bus for the purpose of evaluation.