A brief history of the numeric keypad

Summary

Here is where the story gets interesting. Why did Felt choose to display the numbers in a 9 to 1 sequence? It wasn’t a widespread notion at the time. After all, the knowledge of arithmetical devices was not as widespread.A reasonable answer could be tied to some mechanical decisions, possibly related to the method of complements and the fact that keys were pressing levers connected to rotating drums (Durant, 2011). The longer stick was equal to a longer rotation, which meant to be the number 9, as opposed to number 1 which required a shorter rotation — a suggestion from an older concept by Parmelee.Another interesting explanation — from a modern design standpoint — goes beyond the mechanical reasons. According to the Comptometer Manual, operators were meant to input numbers by using the lowest values on the keyboard. For instance, in order to enter “9 cents”, the operator was not supposed to press the 9 key at the very right column. Instead, they were to press, in sequence, the 4 and 5 key. The machine would do the math. Reaching for the “9” key was deprecated because it decreased the figuring speed if users had to move their right hand from the bottom. Felt was all about efficiency, which meant keeping commonly used keys within the fingers’ reach. It seems this need for efficiency led to this user-centered design layout, but it was still not considered a user-friendly interface (Meehan, 1952).The Comptometer and its competitors required highly-trained users to attain maximum productivity. It was also difficult to do with one hand, especially when it came to multiplications.In 1902, the Dalton went on to become one of the most popular 10-key adding machines of the time, rendering multi-column calculators obsolete. Dalton was a miniature version of a typewriter and had two rows of five buttons with an odd arrangement — 24579 at the top and 13068 at the bottom. What’s different in the arrangement that was not seen up until now? (Durant, 2011)That’s right! The 0 finall...