Exemplary embodiments for SRAM cells, new control units for SRAM systems, and embodiments of SRAM systems are described herein. An SRAM cell is configured to receive a first input voltage signal and a second input voltage signal with a different value from the first input voltage signal, and to maintain a first stored value signal and a second stored value signal. A control circuit is configured to receive a first input voltage signal and a second input voltage signal, and controlled by a sleep signal, a selection signal, and a data input signal, so that the output of the control circuit is data sensitive to the data input signal. An SRAM system comprises a plurality of SRAM cells, controlled the disclosed control circuit wherein an SRAM cell has two input voltage signals controlled by a data input signal and its complement signal respectively.