Semiconductor device verifying signal supplied from outside

Abstract

Disclosed herein is a semiconductor device that includes an access control circuit generating an internal command based on a verification result signal and an external command. The external command indicates at least one of a first command that enables the access control circuit to access a first circuit and a second command that enables the access control circuit not to access the first circuit or enables the access control circuit to maintain a current state of the first circuit. The access control circuit, when the verification result signal indicates a first logic level, generates the internal command based on the external command. The access control circuit, when the verification result signal indicates a second logic level, generates the internal command that corresponds to a second command even if the external command indicates a first command.

What is claimed is: 
     
         1 . A semiconductor device comprising:
 an access control circuit generating an internal command based on an external command, the external command including a first bit and a plurality of second bits supplied from outside; and   a first circuit operating based on the internal command supplied from the access control circuit, wherein the external command indicates at least one of a first command that enables the access control circuit to access the first circuit and a second command that enables the access control circuit not to access the first circuit or enables the access control circuit to maintain a current state of the first circuit.