This paper introduces SmartPad, a new input device for mobile computers that is an enhanced physical keypad by a finger position sensor. This input device acts as a normal keypad for mobile devices, such as cellular phones, and also recognizes finger position on the keypad be before the user presses the key. This feature is used to recognize finger gesture on the keypad, and can also be used to give preview information to the user before the user actually pressing the key. This previewable function helps users to predict the effect of the action, and it is also helpful when the key definitions are frequently changed according to the context, such as in the case of universal commanders. Keywords mobile devices, predictable user interface, touch-sensitive user interface, SmartSkin