New gridded maps of Koeppen's climate classification

An intelligent refreshing method and apparatus for increasing multi-level non-volatile memory charge retention reliability is described. In one embodiment, the apparatus comprises a circuit that is coupled to a multi-level memory cell and a sensing circuit. The sensing circuit senses a voltage of the memory cell and provides a digital value in response thereto. The circuit includes a selection circuit that receives the digital value and at least one trigger voltage, and provides an output trigger voltage responsive to the digital value. The circuit further includes a comparator having a first terminal coupled to receive the output trigger voltage, a second terminal coupled to receive the memory cell voltage, and an output terminal.