diff --git a/README.md b/README.md
index f878df6..3813f64 100644
--- a/README.md
+++ b/README.md
@@ -579,7 +579,9 @@ cd ..\pipelined-cpu
 
 ```powershell
 # ① 建仿真快照（只在第一次，或改了 RTL 之后需要重跑）
-cd <随便一个空目录，例如 D:\risc-v-cpu\_tmp\saolei_sim>
+cd D:\Desktop\risc-v-cpu
+New-Item -ItemType Directory -Force -Path _tmp\saolei_sim | Out-Null   # 用哪个空目录都行
+cd _tmp\saolei_sim
 $p  = 'D:\Desktop\risc-v-cpu\pipelined-cpu'
 $rtl = (Get-ChildItem "$p\srcs\rtl\*.v").FullName
 & 'C:\Xilinx\Vivado\2020.2\bin\xvlog.bat' -d SAOLEI_ROM -i "$p\srcs\board" -i "$p\srcs\rtl" $rtl "$p\srcs\board\cpu21_board_top.v" "$p\srcs\tb\tb_saolei_play.v"