A system to generate true random numbers includes a RAM array, a null-read controller and a hash generator. The RAM array has memory cells and a sense amplifier. The memory cells store data therein, the cells are connected in rows to word lines and in columns to pairs of bit lines, and the sense amplifier senses a differential input signal. The null-read controller implements a null-read operation by the sense amplifier of a portion of the RAM array. The hash generator receives a null-read result from the null-read operation and outputs a partial true random number based on the null read result.