<P> The first electronic keyboards had a typewriter key travel distance of 0.187 inches (4.75 mm), keytops were a half - inch (12.7 mm) high, and keyboards were about two inches (5 cm) thick . Over time, less key travel was accepted in the market, finally landing on 0.110 inches (2.79 mm). Coincident with this, Key Tronic was the first company to introduce a keyboard that was only about one inch thick . And now keyboards measure only about a half - inch thick . </P> <P> Keytops are an important element of keyboards . In the beginning, keyboard keytops had a "dish shape" on top, like typewriters before them . Keyboard key legends must be extremely durable over tens of millions of depressions, since they are subjected to extreme mechanical wear from fingers and fingernails, and subject to hand oils and creams, so engraving and filling key legends with paint, as was done previously for individual switches, was never acceptable . So, for the first electronic keyboards, the key legends were produced by two - shot (or double - shot, or two - color) molding, where either the key shell or the inside of the key with the key legend was molded first, and then the other color molded second . But, to save cost, other methods were explored, such as sublimation printing and laser engraving, both methods which could be used to print a whole keyboard at the same time . </P> <P> Initially, sublimation printing, where a special ink is printed onto the keycap surface and the application of heat causes the ink molecules to penetrate and commingle with the plastic modules, had a problem because finger oils caused the molecules to disperse, but then a necessarily very hard clear coating was applied to prevent this . Coincident with sublimation printing, which was first used in high volume by IBM on their keyboards, was the introduction by IBM of single - curved - dish keycaps to facilitate quality printing of key legends by having a consistently curved surface instead of a dish . But one problem with sublimation or laser printing was that the processes took too long and only dark legends could be printed on light - colored keys . On another note, IBM was unique in using separate shells, or "keycaps", on keytop bases . This might have made their manufacturing of different keyboard layouts more flexible, but the reason for doing this was that the plastic material that needed to be used for sublimation printing was different from standard ABS keytop plastic material . </P> <P> Three final mechanical technologies brought keyboards to where they are today, driving the cost well under $10: </P>

Explain the various type of keys of a keyboard