Your keyboard's ancestors sent stock prices down telegraph wires
The keyboard on your desk descends less from the typewriter than from two workhorses of the telegraph and census era: the teleprinter, which relayed stock prices as early as the 1870s, and Herman Hollerith's card keypunch. Those machines passed their layouts to early computers, and the keyboard reigned alone until the mouse reached consumers in 1984.
Teleprinter-like devices were typing and transmitting market data to ticker tape in the 1870s. The modern teleprinter took shape between 1907 and 1910 in the hands of Charles Krum and his son Howard, with help from Frank Pearne. Meanwhile Hollerith's keypunches, used to encode data on cards, gained typewriter-style letter and number keys by the 1930s. For much of the 20th century one machine handled communication and the other data storage, and the first computers borrowed from both: ENIAC used a keypunch for input and output, and BINAC recorded typed data onto magnetic tape.
A modern keyboard does not actually send letters. Each press produces a scan code identifying which physical key moved, and software decides what it means, which is how one board can serve many languages. Most full-size boards follow one of three mechanical layouts, set by international, American and Japanese standards. American-style boards usually have 104 keys, and the rest of the world typically uses 105. Keys on the American standard sit 19 millimetres apart and travel at least 3.8 millimetres. Many people now drop the number pad entirely, a style known as tenkeyless.
Variants multiplied to suit different jobs. Laptops use shorter-travel scissor switches, while full-size boards more often rest on rubber domes. Washable silicone keyboards roll up and suit hospitals. Handheld models are gripped like game controllers, thumb boards defined early BlackBerry phones, and control rooms and trading floors use programmable boards that switch between several computers.
Comfort has been studied for a century. A 1926 study by Klockenberg suggested splitting the keys into two angled halves so the wrists could stay straight, and Kroemer in 1972 examined adjustable split designs and user pain. Douglas Engelbart, better known for the mouse, also invented a chorded keyboard for one hand.
Source: Computer keyboard
