An optical memory cell that has four distinctive states, therefore storing 2 bits of information optically, is demonstrated by utilizing a novel single semiconductor microring laser with a retro-reflector cavity. To our best knowledge, it is the first time the combination of two directional and two wavelength states with a single semiconductor ring laser of only 20 times 62 mum² in size has been demonstrated in which room-temperature continuous-wave operation is realized. These states can be easily written by corresponding optical inputs with low optical energy of ~ 1.56 fJ and rapid access time of ~70 ps suitable for 10 Gb/s or higher data rates.