Riiven Slants
Seven on Top
Bell Labs tested sixteen keypad layouts, and the calculator beside the phone still counts from the bottom.
A calculator puts 7, 8, 9 across its top row. A telephone puts 1, 2, 3 there. Both keypads sit in the same hand, and Bell Labs measured which one people wanted.
Pick up a phone and the 1 sits in the upper left corner. Pick up a calculator and the 1 sits near the bottom. The ten key adding machine had its bottom up order before Bell built a pushbutton phone. The two layouts are mirror images on one desk.
In 1955 Mary Champion Lutz and Alphonse Chapanis asked 100 people to write the digits onto blank diagrams of ten button keysets. The most common answer put them in horizontal rows, left to right, starting at the top. They read the keypad like a page. Expectation, not speed, pointed the order downward.
In July 1960 R. L. Deininger published the Bell Labs follow up in the Bell System Technical Journal. He screened sixteen arrangements and tested five finalists. The adding machine order went into the early comparison and was not the best performer. The margins were small, and rectangular grids also offered engineering advantages.
Touch Tone service opened on November 18, 1963, in Carnegie and Greensburg, Pennsylvania, with 1, 2, 3 across the top. A folk story says Bell flipped the calculator to slow fast operators so switching gear could keep up. The primary studies contain nothing of the kind. The order was measured.
Calculators kept their order. The 1988 edition of CCITT Recommendation E.161 made the telephone grid the standard and allowed the calculator's row order as an exception for devices used mainly for data entry. Two sensible conventions now share one phone screen, upside down from each other.
The tilt
The adding machine order lost a close test at Bell Labs and stayed on calculators anyway. The standard that fixed the telephone grid still permits it for data entry.
Sources
- Mary Champion Lutz and Alphonse Chapanis, “Expected Locations of Digits and Letters on Ten-Button Keysets,” Journal of Applied Psychology 39(5) (1955)
- R. L. Deininger, “Human Factors Engineering Studies of the Design and Use of Pushbutton Telephone Sets,” Bell System Technical Journal 39(4) (1960)
- Hagley Museum and Library, “On this date, November 18, 1963, Bell Telephone began offering the world’s first commercial service for an electronic push-button, touch-tone telephone” (2024)
- CCITT Recommendation E.161, Arrangement of Digits, Letters and Symbols on Telephones and Other Devices That Can Be Used for Gaining Access to a Telephone Network (1988)
