In PC-compatible machines, the [Shift], [Ctrl], and [Alt] keys affect the interpretation of a scancode with ascending priority. That is, the [Alt] key has the highest priority. If [Alt] is pressed, the [Shift] and [Ctrl] keys have no affect. Likewise, if [Ctrl] is pressed, the [Shift] key has no affect. On the HP palmtop, there are a few exceptions to this that are necessary for compatibility because the HP palmtop has a non-standard keyboard, and certain keys are shifted on the HP palmtop, but not on the standard keyboards and vice versa. For example, the following keycodes can be obtained on the HP palmtop: