diff --git a/notes/memory-layout.md b/notes/memory-layout.md
index 6baa8b7..02640d6 100644
--- a/notes/memory-layout.md
+++ b/notes/memory-layout.md
@@ -2,10 +2,11 @@
 - bank switching using 8-Bit register
 - top 32K remain untouched
 
-| start  | end    | use |
-| :----- | :----- | :-- |
-| 0x8000 | 0xDFFF | RAM |
-| 0xE000 | 0xFFFF | ROM |
+| start  | end    | use                     |
+| :----- | :----- | :---------------------- |
+| 0x8000 | 0x8000 | bank switching register |
+| 0x8001 | 0xDFFF | RAM                     |
+| 0xE000 | 0xFFFF | ROM                     |
 
 # Default (0X00)
 | start  | end    | use |