A telephone keypad using the ITU E.161 standard.Numeric keypad, integrated with a computer keyboardA calculator1984 flier for projected capacitance keypad
A computer keyboard usually has a small numeric keypad on the side, in addition to the other number keys on the top, but with a calculator-style arrangement of buttons that allow more efficient entry of numerical data. This number pad (commonly abbreviated to numpad) is usually positioned on the right side of the keyboard because most people are right-handed.
Many laptop computers have special function keys that turn part of the alphabetical keyboard into a numerical keypad as there is insufficient space to allow a separate keypad to be built into the laptop's chassis. Separate external plug-in keypads can be purchased.
Keypads for the entry of PINs and for product selection appear on many devices including ATMs, vending machines, point of sale payment devices, time clocks, combination locks and digital door locks.
In 1984, the first projected capacitance keypad was used to sense through the shop window of a travel agency (see projected capacitance/window keypad image).[1] Later, they were installed in many Tourist Information shop windows throughout the UK. Due to their ability to operate through thick glass, and be unaffected by spilt beer, in 1990 projected capacitance keypads were used by MHG (Music Hire Group) to replace the selection keys in Pub Juke Boxes.[2]
Key layoutEdit
The first key-activated mechanical calculators and many cash registers used "parallel" keys with one column of 0 to 9 for each position the machine could use. A smaller, 10-key input first started on the Standard Adding Machine in 1901.[3] The calculator had the digit keys arranged in one row, with zero on the left, and 9 on the right. The modern four-row arrangement debuted with the Sundstrand Adding Machine in 1911.[4]
There is no standard for the layout of the four arithmetic operations, the decimal point, equal sign or other more advanced mathematical functions on the keypad of a calculator.
The invention of the push-button telephone keypad is attributed to John E. Karlin, an industrial psychologist at Bell Labs in Murray Hill, New Jersey.[5][6] On a telephone keypad, the numbers 1 through 9 are arranged from left to right, top to bottom with 0 in a row below 789 and in the center. Telephone keypads also have the special buttons labelled * (star) and # (octothorpe, number sign, "pound", "hex" or "hash") on either side of the zero key. The keys on a telephone may also bear letters which have had several auxiliary uses, such as remembering area codes or whole telephone numbers.
Origin of the order differenceEdit
Although calculator keypads pre-date telephone keypads by nearly thirty years, the top-to-bottom order for telephones was the result of research studies conducted by a Bell Labs Human Factors group led by John Karlin. They tested a variety of layouts including a Facit like the two-row arrangement, buttons in a circle, buttons in an arc, and rows of three buttons.[5] The definitive study was published in 1960: "Human Factor Engineering Studies of the Design and Use of Pushbutton Telephone Sets" by R. L. Deininger.[7][8] This study concluded that the adopted layout was best, and that the calculator layout was about 3% slower than the adopted telephone keypad.
Despite the conclusions obtained in the study, there are several popular theories and folk histories explaining the inverse order of telephone and calculator keypads.
One popular theory suggests that the reason is similar to that given for the QWERTY layout, the unfamiliar ordering slowed users to accommodate the slow switches of the late 1950s and early 1960s.[9]
Another explanation proposed is that at the time of the introduction of the telephone keypad, telephone numbers in the United States were commonly given out using alphabetical characters for the first two digits. Thus 555-1234 would be given out as KL5-1234. These alpha sequences were mapped to words. "27" was given out as "CRestview", "26" as "ATwood", etc. By placing the "1" key in the upper left, the alphabet was arranged in the normal left-to-right descending order for English characters. Additionally, on a rotary telephone, the "1" hole was at the top, albeit at the top right.
A mechanically-switched 16-key keypad can be connected to a host through 16 separate connecting leads, plus a ground lead (Figure 1, left). Pressing a key will short to ground, which is detected by the host. This design allows any number or combination of keys can be pressed simultaneously. Parallel-in serial-out shift registers may be used to save I/O pins.
These 16 + 1 leads can be reduced to just 8 by using x/y multiplexing (Figure 1, center). A 16-key keypad uses a 4 × 4 array of 4 I/O lines as outputs and 4 as inputs. A circuit is completed between an output and an input when a key is pressed. Each individual keypress creates a unique signal for the host. If required, and if the processor allows, two keys can be pressed at the same time without ambiguity. Adding diodes in series with each key prevents key ghosting, allowing multiple simultaneous presses.
8 leads can detect many more keys if tri-state multiplexing (Figure 1, right) is used instead, which enables (n-1) × (n/2) keys to be detected with just n I/O lines. 8 I/O can detect 28 individual keys without ambiguity. Issues can occur with some combinations if two keys are pressed simultaneously. If diodes are used, then the number of unique keys detectable is doubled.[10]
^ abFox, Margalit (2013-02-08). "John E. Karlin, Who Led the Way to All-Digit Dialing, Dies at 94". The New York Times. Retrieved 2013-02-09.
^. The Star-Ledger. 2013-02-09. Archived from the original on 2013-02-13. Retrieved 2013-02-09.
^Deininger, R. L. (July 1960). (PDF). The Bell System Technical Journal. 39: 995. doi:10.1002/j.1538-7305.1960.tb04447.x. Archived from the original (PDF) on 2014-01-24. Retrieved 2014-02-07.
^Feldman, Dave (1987). Why Do Clocks Run Clockwise. New York, USA: Harper & Row.
^"Why is the keypad arrangement different for a telephone and a calculator?". How Stuff Works. 2001-05-22. Retrieved 2014-02-07.
Look up keypad in Wiktionary, the free dictionary.
Interfacing Matrix Keypad to 8051 Controller
October 15, 2023
keypad, keypad, block, buttons, with, arrangement, digits, symbols, alphabetical, letters, pads, mostly, containing, numbers, used, with, computers, numeric, keypads, found, devices, which, require, mainly, numeric, input, such, calculators, television, remote. A keypad is a block or pad of buttons set with an arrangement of digits symbols or alphabetical letters Pads mostly containing numbers and used with computers are numeric keypads Keypads are found on devices which require mainly numeric input such as calculators television remotes push button telephones vending machines ATMs point of sale terminals combination locks safes and digital door locks Many devices follow the E 161 standard for their arrangement A telephone keypad using the ITU E 161 standard Numeric keypad integrated with a computer keyboardA calculator1984 flier for projected capacitance keypad Contents 1 Uses and functions 2 Key layout 3 Origin of the order difference 4 Keypad track design 4 1 Separate connections 4 2 X Y multiplexing 4 3 Charlieplexing 5 See also 6 References 7 External linksUses and functions EditA computer keyboard usually has a small numeric keypad on the side in addition to the other number keys on the top but with a calculator style arrangement of buttons that allow more efficient entry of numerical data This number pad commonly abbreviated to numpad is usually positioned on the right side of the keyboard because most people are right handed Many laptop computers have special function keys that turn part of the alphabetical keyboard into a numerical keypad as there is insufficient space to allow a separate keypad to be built into the laptop s chassis Separate external plug in keypads can be purchased Keypads for the entry of PINs and for product selection appear on many devices including ATMs vending machines point of sale payment devices time clocks combination locks and digital door locks In 1984 the first projected capacitance keypad was used to sense through the shop window of a travel agency see projected capacitance window keypad image 1 Later they were installed in many Tourist Information shop windows throughout the UK Due to their ability to operate through thick glass and be unaffected by spilt beer in 1990 projected capacitance keypads were used by MHG Music Hire Group to replace the selection keys in Pub Juke Boxes 2 Key layout EditThe first key activated mechanical calculators and many cash registers used parallel keys with one column of 0 to 9 for each position the machine could use A smaller 10 key input first started on the Standard Adding Machine in 1901 3 The calculator had the digit keys arranged in one row with zero on the left and 9 on the right The modern four row arrangement debuted with the Sundstrand Adding Machine in 1911 4 There is no standard for the layout of the four arithmetic operations the decimal point equal sign or other more advanced mathematical functions on the keypad of a calculator The invention of the push button telephone keypad is attributed to John E Karlin an industrial psychologist at Bell Labs in Murray Hill New Jersey 5 6 On a telephone keypad the numbers 1 through 9 are arranged from left to right top to bottom with 0 in a row below 789 and in the center Telephone keypads also have the special buttons labelled star and octothorpe number sign pound hex or hash on either side of the zero key The keys on a telephone may also bear letters which have had several auxiliary uses such as remembering area codes or whole telephone numbers Origin of the order difference EditAlthough calculator keypads pre date telephone keypads by nearly thirty years the top to bottom order for telephones was the result of research studies conducted by a Bell Labs Human Factors group led by John Karlin They tested a variety of layouts including a Facit like the two row arrangement buttons in a circle buttons in an arc and rows of three buttons 5 The definitive study was published in 1960 Human Factor Engineering Studies of the Design and Use of Pushbutton Telephone Sets by R L Deininger 7 8 This study concluded that the adopted layout was best and that the calculator layout was about 3 slower than the adopted telephone keypad Despite the conclusions obtained in the study there are several popular theories and folk histories explaining the inverse order of telephone and calculator keypads One popular theory suggests that the reason is similar to that given for the QWERTY layout the unfamiliar ordering slowed users to accommodate the slow switches of the late 1950s and early 1960s 9 Another explanation proposed is that at the time of the introduction of the telephone keypad telephone numbers in the United States were commonly given out using alphabetical characters for the first two digits Thus 555 1234 would be given out as KL5 1234 These alpha sequences were mapped to words 27 was given out as CRestview 26 as ATwood etc By placing the 1 key in the upper left the alphabet was arranged in the normal left to right descending order for English characters Additionally on a rotary telephone the 1 hole was at the top albeit at the top right Keypad track design Edit nbsp Figure 1 Keypad wiring methods separate connections left x y multiplexing center Charlieplexing right Separate connections Edit A mechanically switched 16 key keypad can be connected to a host through 16 separate connecting leads plus a ground lead Figure 1 left Pressing a key will short to ground which is detected by the host This design allows any number or combination of keys can be pressed simultaneously Parallel in serial out shift registers may be used to save I O pins X Y multiplexing Edit See also Keyboard matrix circuit These 16 1 leads can be reduced to just 8 by using x y multiplexing Figure 1 center A 16 key keypad uses a 4 4 array of 4 I O lines as outputs and 4 as inputs A circuit is completed between an output and an input when a key is pressed Each individual keypress creates a unique signal for the host If required and if the processor allows two keys can be pressed at the same time without ambiguity Adding diodes in series with each key prevents key ghosting allowing multiple simultaneous presses Charlieplexing Edit Main article Charlieplexing 8 leads can detect many more keys if tri state multiplexing Figure 1 right is used instead which enables n 1 n 2 keys to be detected with just n I O lines 8 I O can detect 28 individual keys without ambiguity Issues can occur with some combinations if two keys are pressed simultaneously If diodes are used then the number of unique keys detectable is doubled 10 See also EditArrow keys Charlieplexing Digital door lock Keyboard computing Keyboard matrix circuit Keyboard technology Key rollover Mobile phone Push button telephone Silicone rubber keypad Telephone keypadReferences Edit Binstead Ronald Peter 1985 04 16 Touch operated keyboard Archived from the original on 2018 01 31 Retrieved 2018 01 30 A Brief History of Projected Capacitance Development by Binstead Designs Retrieved 2023 08 27 William and Hubert Hopkins machines Retrieved 2017 07 18 Sundstrand Adding Machine Underwood Sundstrand Retrieved 2017 07 18 a b Fox Margalit 2013 02 08 John E Karlin Who Led the Way to All Digit Dialing Dies at 94 The New York Times Retrieved 2013 02 09 Monmouth man inventor of touch tone keypad dies at 94 The Star Ledger 2013 02 09 Archived from the original on 2013 02 13 Retrieved 2013 02 09 Deininger R L July 1960 Human Factor Engineering Studies of the Design and Use of Pushbutton Telephone Sets PDF The Bell System Technical Journal 39 995 doi 10 1002 j 1538 7305 1960 tb04447 x Archived from the original PDF on 2014 01 24 Retrieved 2014 02 07 Feldman Dave 1987 Why Do Clocks Run Clockwise New York USA Harper amp Row Why is the keypad arrangement different for a telephone and a calculator How Stuff Works 2001 05 22 Retrieved 2014 02 07 Touch sensor Retrieved 2023 08 04 External links Edit nbsp Look up keypad in Wiktionary the free dictionary Interfacing Matrix Keypad to 8051 Controller Retrieved from https en wikipedia org w index php title Keypad amp oldid 1178190198, wikipedia, wiki, book, books, library,
