Data processing device formed on a single semiconductor substrate having secure memory

Claim 1

A data processing device formed on a single semiconductor substrate comprising: a central processing means for preforming data processing operations upon data in accordance with instructions, said data processing operations including at least one memory access operation for recall of data or an instruction stored in a specified address location; a nonvolatile memory means having a plurality of address locations which are a subset of the possible address locations of said at least one memory access operation, for storing data and instructions which define data processing operations at respective address locations; an information transfer means connected to said central processing means and said nonvolatile memory means for transfer of data and instructions; an external interface means connected to said information transfer means for providing information to at least one device external to said single semiconductor substrate; at least one security bit memory means, each for storing therein a single bit of data indiating a secure state when said nonvolatile memory means is to be secure to a nonsecure sytate; an address logic means connected to said information transfer bus for generating a protected access signal when a memory access operation specifies one of said address locations of said nonvolatile memory means; and an external interface inhibit logic means connected to said at least one security bit memory means, said external interface means and said address logic means for inhibiting said external interface means thereby preventing transfer of information to said at least one external device when any of said at least one security bit memory means indicates said secure state and said address logic means generates said protected access signal.