On-chip microprocessor instruction decoder having hardware for selectively bypassing on-chip circuitry used to decipher encrypted instruction codes

摘要

A microprocessor has on-chip hardware for protecting software against unauthorized use. The microprocessor includes a decoder for deciphering software instruction codes prior to their execution by the microprocessor. The instruction codes are enciphered in a unique way so that they can only be executed by the specific microprocessor for which they are intended.