Screen-labeled function keys: Difference between revisions

Revision as of 23:01, 29 September 2008

Revision as of 01:14, 1 October 2008

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[[Image:ATMscreen.jpg|thumb|right|300px|ATM in [[Mercer Island, Washington]] with function keys]]

'''Screen-labeled function keys''' are a special case of [[function keys]] where keys are placed near a screen, which provides labels for them. These are most commonly found in kiosk applications, such as [[automated teller machine]]s and [[gas pump]]s. These were first developed by [[Hewlett-Packard]] in the 1970s.{{Fact|date=September 20092008}} 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 later adapted to terminals. 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.

[[As of 2008]], HP calculators use this arrangement to implement hierarchical trees of functions.{{Fact|date=September 2008}} 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 were 12 function keys, patterned after use on IBM terminals.