| 摘要 |
PURPOSE:To protect secret of data which are stored by equipping a logic conversion circuit which converts logic of external output signals by output signals of an address detecting circuit which detects specific address selection using a memory-cell array and an address signal. CONSTITUTION:A logic conversion circuit 8 enables an output signal D to the condition of reverse or non-reverse rotation for an input signal (d) of the logic conversion circuit 8 by transfer gates T1 and T2 which are controlled by outputs Q and Q' of a flip-flop FF1 which makes phi1 as an input signal, and enables to set logic of ROM output to positive or negative logic. Therefore, when a specific address, which is set by a code setting part, is selected, logic of ROM output is converted from positive to negative logic or vice versa, and therefore, when the data, which are stored in ROM, are read without distinguishing the specific address from other addresses, wrong data are read, and as a result, secret is protected. |
