Importance

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Abstract

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 contained in the external memory. To verify that the external memory is authentic, duplicate semiconductor devices, for example microprocessors, are separately mounted with the external memory and in the main unit, respectively. The semiconductor associated with the external memory device acts as a key device and the duplicate device mounted in the main unit acts as a lock device. The key device and the lock device are synchronized with each other, executing the same arithmetic operation according to the same program. The results of these operations are exchanged between devices, and compared. If the results agree, the external memory is determined to be authentic and the main processor unit is allowed to operate; but if the external memory is determined to be false (not authentic), the main unit is left in a reset (disabled) condition.

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First Claim