diff --git a/igs/ peripherals.md b/igs/ peripherals.md
index a449205..6159113 100644
--- a/igs/ peripherals.md	
+++ b/igs/ peripherals.md	
@@ -9,6 +9,8 @@ Each code generator is bind to a range of serial code of IGS GP1 board, thus it'
 
 Obviously, games that aren't slot machine/redemption games won't make use of this device even if running on the GP1 board.
 
+**Note: the following content is based on how code generator works on C/S series slot machine. IGS GP1 may not use all the features, or use them in different ways.**
+
 ## Time Bomb
 
 Time bomb is a way of enforcing revenue sharing when other methods such as contracts or e-cash are considered unfeasible or inappropriate.