Shift key
For lowercase input, since it is not possible to detect whether the keyboard's Shift keys are in use, the common "shift-key mod" connects the Shift key to one of the pins on the motherboard's paddle connector. Compatible applications, including nearly all word processors, can then detect whether the shift key was being pressed. This modification involves adding wires inside the Apple II; Apple distributed literature on how to build it, however, assuring readers that it was "the most simple and least expensive addition anyone could do". Most applications that support lower-case letters can also use the ESC key as a substitute lowercase toggle if the modification is not installed.