Soft key

Soft keys are also found away from the display device, for example on the sides of cellular phones, where they are typically programmed to invoke functions such as PTT, memo, or volume control.

Screen-labeled function keys are today most commonly found in kiosk applications, such as automated teller machines and gas pumps.

Screen-labeled function keys are found in automotive and aviation applications such as in the primary flight and multi-function displays.

Early examples are found in aviation glass cockpits, such as the Mark II avionics of the F-111D in the late 1960s/early 1970s (first ordered 1967, delivered 1970–73).

[citation needed] The HP 9830 desktop computer was the first calculator with two rows of 4 keys, over which a paper overlay would be placed.

Programmers found that the HP 2640 terminals could lock the top two lines of the screen, so they displayed the key functions there.