Method for ensuring security of program data in one-time programmable memory

摘要

This application describes a method of protecting data and program code stored in an EPROM array from piracy. The security scheme allows for segmentation of the array to protect one section of the array from reading while programming a non-secure section. The security scheme also allows for protection of the entire array after programming is complete. It also incorporates a device to prevent tampering with the segmentation registers and a means to prevent circumvention of the security scheme even when the processor is in one or more of its test modes.