There are two mode control select pins (M1 and M2), which allow the user to set the correct read protocol for the design. The GS815018/36A support single clock Pipeline mode, which directly affects the two mode control select pins. In order for the part to fuction correctly, and as specified, M1 must be tied to VSS and M2 must be tied to VDD or VDDQ. This must be set at power-up and should not be changed during operation.