A system is disclosed for determining the authenticity of computer software when used with a main processor unit. The software is stored in an external memory which may, for example, be in the form of a ROM cartridge, floppy disk or the like. The main processor unit is operated according to a program...http://www.google.com.au/patents/US4799635?utm_source=gb-gplus-sharePatent US4799635 - System for determining authenticity of an external memory used in an information processing apparatus
