https://blog.wongcw.com/2020/09/07/dram%e8%a3%bd%e9%80%a0%e5%95%86%e5%8d%97%e4%ba%9e%e7%a7%91%e6%8a%808%e6%9c%88%e4%bb%bd%e7%87%9f%e6%94%b6%e5%90%8c%e6%af%94%e7%92%b0%e6%af%94%e5%9d%87%e4%b8%8b%e6%bb%91/