| 摘要 |
A nonvolatile memory device (10) has a signature code generator (14, 15, 17) generating a present signature code (Q) from an algorithm modified dynamically as a function of predefined varying parameters. A variable parameter may be the address (A) of a memory cell being addressed; in this case the output of the code generator (Q) is a function of data (D) read from the cell array (24), the previously calculated signature code (Q) and the address of the read data. The data are read in sequence, using an internal clock (CK) generated by an internal clock oscillator (11). In test mode, the memory is scanned sequentially, beginning from any memory location, selected randomly, and the signature code (Q) varies in dynamic way; at the end of memory scanning, the signature code (Q) is compared to an expected result. <IMAGE> |
