A variety of memory and logic devices, including DRAM (dynamic random access memory), SDRAM (synchronous dynamic random access memory), Flash memory (NAND or NOR), CPU (central processing unit), GPU (graphics processing unit), etc., are widely used in computers, digital music players, gaming devices and mobile internet devices. For instance, since SDRAM was introduced to computers, further generations of SDRAM (DDR1, DDR2 and DDR3) have entered the mass market, with DDR4 currently being designed and anticipated to become available in the coming years.