- For other uses, see Dial (disambiguation).
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Rotary dial
In telephony and telecommunications in connection with a telephone, a dial refers, in older telephones, to a rotating disk with 10 numbered finger holes - a rotary dial. When a particular numbered hole is rotated with the finger to a finger stop set at a specific point across the dial, then released, the dial mechanism rotates the dial back to its original position and transmits pulses down the telephone line according to the number of the hole selected.
Tone Dial
In the early 1960s Bell Telephone Laboratories researched various key pad layouts to replace the telephone dial, for electronic telephone equipment. Researchers rearranged the dial numbers in a wide range of combinations from mimicking a telephone dial to the now familiar 4 row by 3 column keypad. They found the 4x3 keypad to be the fastest and most error free arrangement to operate. However, because the American telephone dial had the 0 next to the 9, they tested the arrangement with a 1 at the top and 0 at the bottom, below the 8 key. They also tested an arrangement with the 0 below the 2 and having 9 at the top, as appeared on adding machines at that time and now appears on computer and calculator keyboards, but that arrangement was more error prone as few people were familiar with adding machines at that time. Because of this research, phone key pad numbering is reversed to today's calculator and computer keyboards. However, the keypads of most cash machines usually have the same numbering as phone key pads.
Sources
- R.B. Hill Early Work on Dial Telephone Systems January, 1953 Bell Laboratories Record. (Volume XXXI No. 1, January, 1953. P. 22 et. seq.)
