A modification of a predetermined, memory-size-dependant number of nonvolatile memory cells turns them into ROM cells with a fixed content pattern. Since these additional ROM cells do not require much effort during manufacturing and use only small additional space on the memory chip or the integrated circuit, but provide significant advantage for testing. When using pairs of essentially symmetrical non-volatile memory cells, each pair having a common bit line, the removal or interruption of this bitline contact may serve to impress a fixed value, e.g. a ‘0’, into this pair and vice versa. During test, a simple and therefore only minimal time requiring pattern, preferably a checkerboard pattern, is written into and read from the non-volatile memory, allowing a quick determination of the decoders' correct function.