SEMICONDUCTOR MEMORY DEVICE

PURPOSE:To keep the program secrecy of a customer by carrying out the coding processing based on the output or/and input data addresses that momentarily change. CONSTITUTION:The address signal. groups A1-AM which are given to a semiconductor memory device from a microcomputer, etc., are decoded by an address decoder B, and a certain address is designated at a memory cell part A. The part A outputs the data signal groups d1-dN which are stored in the addresses based on the designated address. Then these groups d1-dN are inputted to the exclusive OR gates G1-GN serving as the coding circuits. Meanwhile N pieces of signals, i.e., some of those groups A1-AM supplied from the outside of the semiconductor memory device are inputted to one of both input terminals of each of groups G1-GM. In such a constitution, the value D1-DN obtained by securing the exclusive OR for each bit are outputted to the outside of the semiconductor memory device.