Techniques for the reading and writing of data in multi-state non-volatile memories are described. Data is written into the memory in a binary format, read into the data registers on the memory, and “folded” within the registers, and then written back into the memory in a multi-state format. In the folding operation, binary data from a single word line is folded into a multi-state format and, when rewritten in multi-state form, is written into a only a portion of another word line. A corresponding reading technique, where the data is “unfolded” is also described. A register structure allowing such a “folding” operation is also presented. One set of embodiments include a local internal data bus that allows data to between the registers of different read/write stacks, where the internal bus can used in the internal data folding process.