Importance

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Abstract

A system for computer software protection includes a random access memory (RAM) device and one or more read-only memory (ROM) devices. The RAM and ROMs are connected in parallel to a data transfer bus, and to an address bus. Selected proprietary portions of a program are pre-stored in the ROMs prior to distribution to system users, and the remaining portions of the program are stored on an external storage medium such as a diskette which is made available for access and use by system users. When using the program, the portion of the program stored on the external storage medium is loaded into the RAM. In executing the program, the system commences executing, in turn, each program instruction contained in the RAM until it is instructed to transfer to one of the ROMs for execution of the proprietary portions of the program stored in the ROMs. If a system user makes an unauthorized copy of the portion of the program stored on the external storage medium, since the proprietary portions of the program are stored in the ROMs, the unauthorized copy will be incomplete and will not be able to run without the proprietary portions of the program which are maintained in the ROMs.

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First Claim