The address space of a data storage device is arbitrarily divided into a plurality of data-segments and a different data scrambling algorithm is assigned to each of the data-segments. A programmable address scrambling device is interposed between the address port of the data storing device and a system...http://www.google.com.au/patents/US5081675?utm_source=gb-gplus-sharePatent US5081675 - System for protection of software in memory against unauthorized use
