What Makes Memory Test Different From Logic Test?
Memory test patterns are purely algorithmic. Each algorithm is designed to address a particular failure mechanism(s). This allows for the use of automatic test pattern generation, where the tester is given an algorithm and generates the actual I/O vectors at the pins. Logic, on the other hand, can not generally be tested in an algorithmic fashion, and the tests must be stored as I/O vectors. Memory test is usually done at a slower speed than logic test and therefore can use cheaper testers. Testing the random logic in a processor core is orders of magnitude more difficult than testing memory – it is harder to write patterns for, to simulate, and to debug. Many more patterns are required compared to the relative small number of algorithms that can be used to test a memory. The time to test a processor relative to testing memory depends on the size of the memory. For smaller memories, it would take longer to test a processor, but for large enough memories, it would take less time. It is
