Acer: Fn + F3
Dell: Fn + F8
Fujitsu: Fn + F5
Gateway: Fn + F3
HP: Fn + F5
IBM: Fn + F7, Fn + F8, Fn + F1, Fn + F3
NEC: Fn + F3
Panasonic: Fn + F2
Samsung: Fn + F4, Fn + F5 or Fn + F6
Sharp: Fn + F5
Sony: Fn + F7
Toshiba: Fn + F5 or Fn + F7
