A memory system includes an X line, a first Y line, a second Y line, a semiconductor region of a first type running along the X line, first switching material and a first semiconductor region of a second type between the first Y line and the semiconductor region of the first type, second switching material and a second semiconductor region of the second type between the second Y line and the semiconductor region of the first type, and control circuitry. The control circuitry changes the programming state of the first switching material to a first state by causing a first current to flow from the second Y line to the first Y line through the first switching material, the second switching material, the semiconductor region of the first type, the first semiconductor region of the second type and the second semiconductor region of the second type.