1. A method, comprising: programming a bi-nitride layer trapped-charge memory device to one of first and second programmed states, corresponding to first and second threshold voltages, or one of first and second erased states, corresponding to third and fourth threshold voltages, wherein the first and second threshold voltages correspond to first and second uniform trapped charge distributions of a first charge type and the third and fourth threshold voltages correspond to first and second uniform trapped charge distributions of a second charge type; and sensing the one of the first and second programmed states or the one of the first and second erased states.