The keyboards most easily available to consumers are based on a simple technology. Under all of the keys is one large sheet of rubber with shaped domes built into it. When you depress a key, one of the domes is inverted, making contact with a circuit board below it. The keyboard’s controller registers this press and sends it to the computer.
This is a fine way to make a keyboard, and it has been working just fine for a long time. But many people have found themselves enthralled with a sort of keyboard made in a different fashion, called a mechanical keyboard. The way these keyboards work is similar to a rubber dome keyboard, where depressing a key closes a circuit and registers as a keypress. But instead of using rubber domes to achieve the detection of a depressed key, a mechanical keyboard has a separate switch, like a momentary push button, for every key on the keyboard. Each of these switches has a dedicated spring and plastic housing that makes the entire experience much more pleasurable for the typist.
The most popular switches are engineered and produced by Cherry, a German company who produces a small share of the world’s mechanical keyboards but a large share of its mechanical keyswitches. Cherry makes its switches in different types, which are referred to by their color coding.
Red and black switches are “linear” switches, which means all you feel as you depress the switch is the force from the spring. At some point during this depression (before you reach the bottom), the switch will register as being depressed. You can, of course, continue to press the key all the way down to the base of the keyboard. This is called “bottoming out” the key, and it makes a considerable noise as the keycap on the switch slams into the base of the keyboard. Red switches are lighter and easier to press than black switches. Cherry also makes brown and clear switches, which have a tactile bump at the point where they register as being pressed. Clear switches are a bit heavier here. Blue and green switches make an audible clicking noise, and provide some tactile feedback, when they register. These are the loudest of the switches, of course, although most of the noise from all of these switch types comes from bottoming out. Blue switches are lighter than the heavy green switches.
Cherry also produces some other less-common colors, but those are the most popular. There is no visual difference in these colors from an initial inspection of the keyboard. Only when you remove the keycaps, the plastic coverings for switches that generally have numbers and letters printed on them, do you see the color of the switch stem.
Being able to remove the keycaps is one of the great features of mechanical keyboards. Most keyboards have standard-sized keycaps, so there is a market for pretty keycap sets, blank keycap sets, and custom keycap sets. Many people like the aesthetic of these modifications, and hardcore touch-typing mechanical keyboard users often don’t mind not having legends on their keycaps. Any keyboard with Cherry MX switches or another switch with the same stem shape and size can use these keycaps interchangeably.
Another occasionally useful feature of mechanical keyboards is n-key rollover. Most mechanical keyboards, and few rubber dome keyboards, support this. N-key rollover means that the computer will be able to recognize every single key you have pressed down, no matter what. Many common keyboards, because of the design of their key recognition matrix, can only recognize up to two keys at a time. It is not the nature of mechanical switches that makes n-key rollover possible, but the developers of expensive keyboards tend to be willing to include those extra features that not as many people will care about.
Consider trying out a mechanical keyboard at your local Best Buy. You might be surprised at how nice it feels.