diff --git a/Chapter6_嵌入式系统/6.2_MCU.md b/Chapter6_嵌入式系统/6.2_MCU.md
index e69de29..8a22580 100644
--- a/Chapter6_嵌入式系统/6.2_MCU.md
+++ b/Chapter6_嵌入式系统/6.2_MCU.md
@@ -0,0 +1,3 @@
+# 6.2 MCU
+
+MCU 是指微控制器单元（Microcontroller Unit；MCU）。
diff --git a/Chapter7_MCU与RTOS/7.1_MCU与RTOS.md b/Chapter7_MCU与RTOS/7.1_MCU与RTOS.md
index 2133a8a..68aa317 100644
--- a/Chapter7_MCU与RTOS/7.1_MCU与RTOS.md
+++ b/Chapter7_MCU与RTOS/7.1_MCU与RTOS.md
@@ -1 +1,3 @@
 # 7.1 MCU 与 RTOS
+
+在第 6 章中提到 MCU 是 Microcontroller Unit 的缩写，即微控制器单。没有接触过 MCU 的人可能很难理解微控制器这个概念，它与 CPU 又有什么差别呢？
diff --git a/Chapter9_嵌入式Linux/8.1_Linux系统架构.md b/Chapter9_SOC与Linux/8.1_Linux系统架构.md
similarity index 100%
rename from Chapter9_嵌入式Linux/8.1_Linux系统架构.md
rename to Chapter9_SOC与Linux/8.1_Linux系统架构.md