It is jolly left over that a estimator and a trace - pure tone telephony have exactly opposite layouts for their keypad , which have many identical component . The reasons behind the differences are not known for certain , but a few theories survive .
The first hypothesis deals with the telephone ’s circuitry and tone - recognition hardware . When the touch - tonetelephonewas being design in the late 1950s , the calculator and adding - auto house decorator had already established a layout that had 7 , 8 and 9 across the top row . Data - first appearance professionals , and others who used calculator pretty regularly , were quite adept at navigating these keypads . They could hit the numbers super cursorily , which was great for data entry , but not so corking for dialing a touch - tone earpiece . The tone - recognition technology could not operate in effect at the speeds at which these specialists could dial the numbers . The telephony room decorator figured that if they reversed the layout , the dialing speeds would decrease and the pure tone - recognition would be able to do its business more faithfully . This theory has small test copy to substantiate it , but it does make sense .
A 2d theory refers to a study done by Bell Labs in 1960 . This study involved testing several different telephone - keypad layouts to line up out which was easiest to master . After testing several layouts , including one that used two row with five numbers each and another that used a circular positioning , it was determined that the three - by - three matrix that had 1 , 2 and 3 across the top was the easiest for citizenry to use .
Another theory is based on the layout of a circular telephone . On a orbitual dial , 1 is at the top right and zero is on the bottom . When designing the new tinge - flavor computer keyboard , putting the 1 on the top - rightfulness did n’t make much sensation , because Western writing is read from go forth to rightfield . But invest 1 on the top - left , and the subsequent phone number to the right , did make sense . Using that expression , the leave rows fell into place , with zero getting its own rowing at the bottom .
All of these theories set about to explicate whytelephoneand calculator keypad are exact opposite , yet no one theory can be nail as the definitive reason . It is common practice today to utilize the phone - computer keyboard layout when design raw product that utilize a computer keyboard , such asAutomated Teller Machines .
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