MS Windows has a number of accessibilty features:
Press down and hold the right SHIFT key for eight seconds: Toggles FilterKeys on and off. FilterKeys is a keyboard feature that instructs the keyboard to ignore brief or repeated keystrokes.
Press down and hold the NUM LOCK key for five seconds: Toggles ToggleKeys on and off. When ToggleKeys is turned on, your computer will provide sound cues when the locking keys (CAPS LOCK, NUM LOCK, or SCROLL LOCK) are pressed.
Press SHIFT five times: Toggles StickyKeys on and off. StickyKeys is designed for people who have difficulty holding down two or more keys simultaneously.



