https://qooah.com/2012/05/18/samsung-20nm-4gb-ram-%e5%b7%b2%e6%8a%95%e5%85%a5%e9%87%8f%e7%94%a2%ef%bc%8c2gb-ram-%e5%b0%87%e6%88%90%e4%b8%bb%e6%b5%81%e8%a6%8f%e6%a0%bc/