Why do numpads on keyboards and phones have reversed layouts?

Question

I came across this on the web. It's supposed to be funny, but we all know better :)

So, why are the numpad layouts different, and what are the reasons behind each?

Answer 1

There's this humongous article called Keyboard Trivia that has collected many of the theories and stories. The summary of facts:

• Touch-tone key pad was designed to mimic the rotary dial with the "1" on top and the 7-8-9 on the bottom, and AT&T conducted user testing to confirm that this configuration helped eliminate dialing errors.
• By the time when the touch-tone telephone was being designed in the late 1950s, the calculator and adding-machine designers had already established a layout that had 7, 8 and 9 across the top row.
• Back then, the industry-standard typical calculator had nine columns of numbers, with 10 numbers in a column, the lowest digits at the bottom, starting with 0 and moving up to 9, and was basically a mechanical adding machine that closely resembled a cash register.
• It is common practice today to use the telephone-keypad layout when designing new products that utilize a keypad, such as Automated Teller Machines.
• When Bell Labs began exploring keypad layouts in the late 1950s they contacted all of the leading calculator manufacturers to find out why they had chosen to put low numbers at the bottom and high numbers at the top rather than the other way around. The answer, apparently, was a big shrug. It turns out that decision was largely arbitrary: no one had done any research about which layout was most convenient for users. Still, when it came time to place a numeric keypad on a computer keyboard, the calculator model with 7-8-9 at the top prevailed.

There's also a theory that phone engineers wanted to slow down people who were fast at entering numerical data, which would jam lines and produce dialing errors, so they reversed the layout. However, records of AT&T Labs' research clearly invalidate it.

Answer 2

One additional possible explanation is that with the calculator layout many calculations can be performed along the bottom two rows and the plus button only; zeroes, decimal points and the enter/equals button.

Since the main buttons are all at the bottom, it makes reasonable sense that the other numbers would count up from the bottom too.

I suspect (but have no proof) that the phone keypad layout would make typing on a calculator more difficult for most simple calculations.