Content-Aware Reduction of Bit Flips in Phase Change Memory

The energy costs of Phase Change Memory (PCM) depends almost completely on the number of bits written per time unit. By using an encoding, we can reduce the number of bit flips when overwriting low-entropy data with low-entropy data. This is achieved by using a frequency table for bytes in classes of data to select the encoding. Using various corpora of mainly HTML files, we show that we can reduce the number of bit flips by about 0.5 bit flips per byte.