Screen labeled function keys

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Screen Labeled Function Keys are a special case of function keys are keys which are placed in close proximity to screen labels. These are most commonly found in kiosk applications such as automated teller machines and gas pumps. These were first developed by Hewlett Packard in the 1970s. The HP 9830 desktop computer was the first calculator with two rows of 4 keys over which a paper overlay would be placed. These were adapted to terminals. Users would, of course, lose these labels. Programmers found that the HP 2640 terminals could lock the top two lines of the screen, so they displayed the key functions there. Starting with HP 2647 terminal, the keys were re-arranged to correspond with 2 pairs of 4 labels at the bottom of the screen. These could be programmed by escape sequence or configuration screen. This would be further developed on the failed HP 300 Amigo, which used keys at the right side of the screen and HP 250 business computers which placed them at the bottom. By arranging functions in hierarchical trees, many functions can be implemented with only 8 keys.

Today, HP calculators use this arrangement to implement hierarchical trees of functions. They are rarely found on PC applications, even though the first IBM PC BASIC labeled function key use at the bottom of the screen, and there are 12 function keys, patterned after use on IBM terminals.

This arrangement has evidently never been patented, but is very commonly used.