A processing unit having a CPU core, an integrated RAM and a test unit, which may be implemented in either a test unit, which may be implemented in either hardware or software. A built-in self-test of the RAM is designed to run concurrently with the functional vectors used to test the CPU...http://www.google.de/patents/US5748640?utm_source=gb-gplus-sharePatent US5748640 - Technique for incorporating a built-in self-test (BIST) of a DRAM block with existing functional test vectors for a microprocessor 
