--- main_not_working.asm	2008-01-25 16:27:21.000000000 +0100
+++ main_working.asm	2008-01-25 16:27:50.000000000 +0100
@@ -104,6 +104,15 @@
 _skip_noa:
  movb	[0x1303], h
 
+ ; Rumble on C.
+ test	a, (1<<2)
+ jnz	_disable_rumble
+ orb	[nn+0x61], 0x10 ; Set 5th bit (rumble bit).
+ jmp	_skip_disable_rumble
+_disable_rumble:
+ andb	[nn+0x61], 0xEF ; Clear 5th bit.
+_skip_disable_rumble:
+
  ; Move up.
  test	a, (1<<3)
  jnz	_noup