Device for protecting a programmable non-volatile memory

A device installed in a computer system for protecting the program or data inside a programmable non-volatile memory. The device includes a first and a second combinatorial logic circuit, a delay circuit, a low-enable latching device with reset capability, an AND gate and a memory cell array. As soon as all the necessary system startup operations dictated by the BIOS program inside the memory cell array are executed and a specified memory read/write program that matches the preset internal parameters of a logic circuit is activated so that output from the AND gate is a logic "false', the memory cell array is permanently locked in a non-programmable state, unless the power is turned off and then restarted again. There is no way for any software program to change the programming state of the memory cell array back to a re-programming state again. Hence, the device is an effective means of protecting the programs inside the memory from illegal tampering.