EINCHIP MIKROCOMPUTER MIT VERSCHLUESSELBARER FUNKTION DES PROGRAMMSPEICHERS.

摘要

A single-chip microcomputer with an encryptable function on program memory encrypts the contents of the memory for protection of secrecy when the programs stored in read only memory (ROM) are read to the outside. An encrypting code generator is provided to execute the encrypting and the encrypting code is stored in an instruction decoder, which decodes the encrypting code and sends it to the arithmetic and logic unit (ALU). The ALU encrypts the data from the ROM based on the encrypting code from the decoder, and outputs the result to the outside on an input/output port.