Re:Why telephone keypads are arranged the way they are
by kd5bjo on Saturday August 29, 2015 @08:40PM
(#10141871)
I don't know which came first, but it might have been to make manufacturing easier give the signaling scheme keypad phones used: when you press a key, two sine waves are generated -- one represents the row and the other the column. There's two groups of 4 frequencies for 16 possible buttons; some radios have an extra column with A-D keys for the extra tones.
Re:Why telephone keypads are arranged the way they are
by DanBC on Sunday August 30, 2015 @02:18AM
(#10142424)
Some military phones used the extra keys as part of autovon.
https://en.wikipedia.org/wiki/Autovon
> The Automatic Voice Network (AUTOVON) was a world-wide American military telephone system. The system was built starting in 1963,
Re:Why telephone keypads are arranged the way they are
by jacobolus on Saturday August 29, 2015 @08:23PM
(#10141837)
By the way, if anyone is trying to design a number pad or calculator keyboard or similar for personal use with the goal being comfort/speed after retraining rather than prior familiarity, I’ve found it works much better to put two numbers on each finger.
Something along the lines of http://i.imgur.com/ofeQEC9.png
This is much better (faster, more comfortable, fewer errors) in my experience than the number row at the top of a keyboard, or a standard 3x3 + 1 grid calculator, computer, or phone keypad.
Re:Why telephone keypads are arranged the way they are
by x0054 on Sunday August 30, 2015 @03:30AM
(#10142585)
You also have to remember that from the beginning they knew they will also need * and # or some kind of extra keys for programming and admin tasks. With touch tone phones came many other innovations in the phone industry. So with 5x2 layout you would actually have to make it 6x2 or 5x2 +2 on the bottom. In both cases it would look and function poorly.
Also, remember that they had a lot of left over molds for rotary phone designs, and they probably intended to retrofit pay phones with rotary dials to touch tone. 3x4 layout fits a lot better into a circle than 5x2 or 6x2.
Here’s a link to a scan where the OCR doesn’t clobber the image http://mrserge.lv/assets/human-factors-engeneering-studies-o...
The lowest errors and fastest keying rate were actually with the standard circular telephone arrangement (most familiar), followed by the two-row five-column layout, and those were also the test subjects’ preferred layouts. In the final test between the 3x3+1 grid vs. the 5x2 grid, the vote tally was 12-3 in favor of the 5x2 gris.
I assume the company’s final choice was based on some engineer or manager’s aesthetic preferences or non-human-factors technical criteria (e.g. it fit better on a particular phone body design), though I’ve never seen any concrete explanations of how the final grid layout was chosen. Or in other words, we still don’t have a solid answer to the question “Why are the numbers on a telephone keypad arranged the way they are?”