A system includes an error correction encoder that encodes data and produces parity bits, and a parity bit processor that disperses the parity bits across the data, placing respective i-bit parity sub-blocks between selected multiple-bit data sub-blocks. The system also modifies one or more of the bits in predetermined positions in respective data sub-blocks based on the bits of the parity sub-blocks that precede them, such that the precoding does not sign invert the data sub-blocks.