diff --git a/src/buttons_effects.c b/src/buttons_effects.c
index 46cf507f..50408364 100644
--- a/src/buttons_effects.c
+++ b/src/buttons_effects.c
@@ -256,8 +256,12 @@ void Button_Constraint_menu(void)
   do
   {
     clicked_button=Window_clicked_button();
-
-    if (clicked_button == 3)
+    if (Is_shortcut(Key, 0x100+BUTTON_HELP))
+    {
+      Key = 0;
+      Window_help(BUTTON_EFFECTS, "8 BIT");
+    }
+    else if (clicked_button == 3)
     {
       Selected_Constraint_Mode = Window_attribute2;
       for (i = 0; i < sizeof(modes)/sizeof(modes[0]) ; i++)
diff --git a/src/helpfile.h b/src/helpfile.h
index 2c97cbd0..3ac0c8bf 100644
--- a/src/helpfile.h
+++ b/src/helpfile.h
@@ -1919,6 +1919,18 @@ static const T_Help_table helptable_effects[] =
   HELP_TEXT ("* Show count : Briefly displays the number")
   HELP_TEXT ("of unique tiles after each analysis.")
   HELP_TEXT ("")
+  HELP_TEXT ("")
+  HELP_TITLE("8 BIT")
+  HELP_TEXT (" This mode enable constraints of the vintage")
+  HELP_TEXT ("8bits computers video modes, such as the ZX")
+  HELP_TEXT ("Spectrum, Commodore 64, etc.")
+  HELP_BOLD ("LEFT CLICK")
+  HELP_TEXT ("Enable/disable the contraints")
+  HELP_TEXT ("")
+  HELP_BOLD ("RIGHT CLICK")
+  HELP_TEXT ("Opens the menu to choose the type of")
+  HELP_TEXT ("constraints")
+  HELP_TEXT ("")
 };
 static const T_Help_table helptable_text[] =
 {