Most memory test algorithms are optimized for a particular memory technology and a particular set of fault models, under the assumption that the memory is bit-oriented, i.e., read and write operations affect only a single bit in the memory. Traditionally, word-oriented memories have been tested by repeated application of a test for bit-oriented memories, whereby a different data background is used during each application. This results in time inefficiencies and limited fault coverage. A systematic way of converting tests for bit-oriented memories into tests for word-oriented memories is presented, distinguishing between interword and intraword faults. The conversion consists of concatenating to the test for interword faults, a test for intraword faults. This approach results in more efficient tests with complete coverage of the targeted faults. Word-oriented memory tests are very important, because most memories have an external data path which is wider than one bit.

Most memory test algorithms are optimized tests for a particular memory technology, and a particular set of fault models, under the assumption that the memory is bit-oriented; i.e., read and write operations affect only a single bit in the memory. Traditionally, word-oriented memories have been tested by repeated application of a test for bit-oriented memories whereby a different data background (which depends on the used intra-word fault model) is used during each iteration. This results in rime inefficiencies and limited fault coverage. A new approach for testing word-oriented memories is presented, distinguishing between inter-word and intra-word faults and allowing for a systematic way of converting tests for bit-oriented memories to rests for word-oriented memories. The conversion consists of concatenating the bit-oriented test for inter-word faults with a test for intra-word faults. This approach results in more efficient tests with complete coverage of the targeted faults. Because most memories have an external data path which is wider than one bit, word-oriented memory tests are very important.

With the increase in memory density, neighborhood pattern sensitive faults (NPSFs) are not only an important fault model for DRAMs but will also become so for SRAMs. NPSFs can be considered generalized versions of simple-cell faults and two-cell coupling faults, whereby the extra cells involved in the NPSF are required to have an enabling value. A new coupling fault model, the disturb fault (CFdst) has been published (van de Goor 1996). It has the property that it is more consistent with the true behavior of the memory, while tests for CFdsts can be designed such that they also cover idempotent CFs. It is the purpose of this paper to extend the concept of CFdsts to NPSFs based on CFdsts (i.e. the Disturb NPSFs) and present tests for those DNPSFs. It will be shown that the tests for DNPSFs are more efficient than those of the traditional tests for NPSFs while they also cover the faults of the traditional NPSFs.