<P> Further the keyboard size depends on the extent to which a system is used where a single action is produced by a combination of subsequent or simultaneous keystrokes (with modifier keys, see below), or multiple pressing of a single key . A keyboard with few keys is called a keypad . </P> <P> Another factor determining the size of a keyboard is the size and spacing of the keys . Reduction is limited by the practical consideration that the keys must be large enough to be easily pressed by fingers . Alternatively a tool is used for pressing small keys . </P> <P> Standard alphanumeric keyboards have keys that are on three - quarter inch centers (0.750 inches, 19.05 mm), and have a key travel of at least 0.150 inches (3.81 mm). Desktop computer keyboards, such as the 101 - key US traditional keyboards or the 104 - key Windows keyboards, include alphabetic characters, punctuation symbols, numbers and a variety of function keys . The internationally common 102 / 104 key keyboards have a smaller left shift key and an additional key with some more symbols between that and the letter to its right (usually Z or Y). Also the enter key is usually shaped differently . Computer keyboards are similar to electric - typewriter keyboards but contain additional keys, such as the command or Windows keys . There is no standard computer keyboard, although many manufacturers imitate the keyboard of PCs . There are actually three different PC keyboards: the original PC keyboard with 84 keys, the AT keyboard also with 84 keys and the enhanced keyboard with 101 keys . The three differ somewhat in the placement of function keys, the control keys, the return key, and the shift key . </P> <P> Keyboards on laptops and notebook computers usually have a shorter travel distance for the keystroke, shorter over travel distance, and a reduced set of keys . They may not have a numerical keypad, and the function keys may be placed in locations that differ from their placement on a standard, full - sized keyboard . The switch mechanism for a laptop keyboard is more likely to be a scissor switch than a rubber dome; this is opposite the trend for full - size keyboards . </P>

How many keys are on microsoft windows standard keyboard