Reading and writing method and system based on multi-level storage type phase change memory

The invention discloses a reading and writing method and system based on a multi-level storage type phase change memory, and belongs to the technical field of read-write control of phase change memory. The reading and writing method comprises a reading method and a writing method, wherein two phase change memory units with multi-level storage capacity are adopted to form a read-write basic unit, and expresses stored 2-bit data based on relative resistance values of the two phase change memory units. The reading method is used for realizing reading data from the read-write basic unit, and the writing method is used for realizing writing data to the read-write basic unit. The read-write system comprises a gating circuit, a reading driving circuit, a read-write basic unit, a reading circuit,a data outputting circuit, a writing operation judging circuit and a writing driving circuit. The invention aims to express data using relative resistance value of a phase change unit in the basic unit based on the multi-leve