A keyboard is an input device which uses typewriter-type keys (called “keycaps”) to deliver text and commands to computers. But they’re much more than that:
Keyboards come in various layouts (ABCDE, XPeRT, QWERTY, AZERTY, DVORAK, Colemak, MIT), often named after the first keys in the pattern, also for the operating systems they control (i.e. Apple, PC, Unix, Linux, etc.)
Also, they come in various sizes and types (roll-up, backlit, ergonomic (see below), gaming, etc.). As I’ve said throughout this site, which keyboard is right for you depends on what you are planning to use it for. Don’t overpay for features you will never need (perhaps gaming, backlighting, wireless) and make sure you get the best features you know you will need (perhaps large type keys).
In 1966, IBM extended the basic QWERTY typewriter keyboard with the addition of function (“Fn”; click HERE to see what they’re about), arrow and control keys (“CTRL” & “CMD”) as well as other keys (home, end, delete, Alt, Esc, etc.) to create the “IBM Standard 101-Key” keyboard, which is still the predominant keyboard in use today. More recent Windows keyboards include the “Windows” key, as Apple has the “Apple” key and Linux the “Tux” and Meta keys, all of which shortcut menu functions within that specific operating system. Further, most keyboards also have a number of “programmable” keys which can be added by users.
Standard IBM-Style Keyboard
HOW THE KEYS WORK
But, essentially, all keyboards work the same, although how they get there is slightly different. Every key is essentially a “switch” which, when depressed, completes a circuit. All of the switches for the keys are contained on what’s known as the “key matrix” which is the grid of circuits below the keys. The electrical impulse created when the circuit is closed then communicates that particular function through a ROM chip on a circuit board on the physical keyboard known as the “character map,” which translates the electrical impulse and sends a command to the computer’s processor for the appropriate
responsive action. There are various technologies used for key switches. Most common today (because they’re lots cheaper) are the “membrane” type, which uses a circuit pattern printed onto a plastic sheet which completes the circuit when a key is pressed against it (see right). Before that, “mechanical” metal contact keyboards were quite popular. They actually had individual spring-loaded keys which used a metal strip at the bottom of a plunger to make the contact, sometimes with an audible “click” (see diagram of
Keyboard microprocessor and controller circuitry, courtesy computer.howstuffworks.com
Corsair K60 key at left, strip on the left side). (Das Key still manufactures these, e.g. Model S Professional Silent model at $135. Also, Func’s KB-460 programmable mechanical keyboard with a Selectric feel, about $120.) Less frequently used now are rubber dome, conductive rubber and foam element switches, as well as “capacitive” switchboards (which run a continuous current but detect changes in that current when keys are depressed), photo-optical (light sensitive), laser (projected, see below), Hall-effect (magnetic), buckling spring and scissor switches (different mechanical construction). For more explanation, click HERE and HERE.
Membrane type keyboard construction, courtesy wikipedia
Early on, some computers had a row of “dip switches,” (see right) which were used to adjust the keyboards (such as the OmniKey 101) to work with various computer configurations, but aside from refurbished ones, they’ve pretty much outlived their usefulness as the result of vast improvements in operating systems. Although some, like the CODE keyboards, use dip switches to reprogram the keyboard for gaming, multimedia and macros.
TYPES OF KEYS
Moreover, keyboards may also be “virtual” (typing on a screen image like an iPad or smart phone; see also Swype for a different way of typing on virtual keyboards), “island,” where all of the keys are separated by a continuous base or “deck” plate surrounding them, “chicklet,” where the flat keys almost touch each other (photo at left for those too young to remember the gum candy), essentially a membrane keyboard with flat low-travel keys or the standard mechanical (“IBM 101 Key”) version discussed above. Below (L to Rt) are chicklet, standard, virtual (phone) and large print keys:
[Related: Keypads, for phones, locks and other devices, developed by John Karlin, see the definitions for more interesting information.]
TYPES OF KEYBOARD CONNECTORS
Lastly, keyboards have differing ways of communicating with the computer’s CPU, including physical connectors (e.g. DIN, PS-2, Apple and USB) and wireless (e.g. Bluetooth, Wi-Fi & infrared) connections. For a more lengthy explanation, click HERE. Depending on the brand and type of your computer, you may need a specific type of connector to connect the keyboard to the computer, so you should check this first when purchasing a keyboard. Adaptors are available, but don’t count on them working well. Depending on the model (there have been about 13), Apple keyboards have special menu keys for CTRL, FN, Option, Alt, Apple, Power and CD/DVD eject. PC keyboards may have the CTRL, Alt and Microsoft Windows keys, depending on the version of the keyboard. Sun Microsystems and Space-cadet (“MIT”) keyboards with the meta and “compose” keys are used with various Linux and Unix systems. All are used for menu shortcuts in combination with other keys.
Shown below (l to r): DIN, PS-2, USB and Wireless keyboard connectors.
KEYBOARD SHAPES AND TYPES
To confuse the issue slightly further, not all keyboards are straight and square. Ergonomic keyboards are shaped, it is claimed, to reduce wrist and finger fatigue. And, in 2012, Microsoft introduced the Sculpt Comfort Keyboard, a wireless Bluetooth keyboard specifically designed for use with Windows 8 tablets and laptops (it updates the Microsoft Wireless Comfort Desktop 5000). Improvements (see photo below): The split spacebar relocates the
backspace key next to the wider space bar, reducing repetitive pinky stress,
and the contour and permanent wrist rest also reduce stress and speed up typing.
Microsoft Sculpt Keyboard
Gaming Keyboard (L), Backlit Keyboard (R) and Floating arms Keyboard (far RT)
For users of multiple devices, there is the Bluetooth mult-device keyboard, which can be used with phones, pads, computers and other devices with the turn of a dial (once paired), all for less than $40.
THE FUTURE IS NOW - LASER PROJECTION
So, what’s the future of keyboards? Look no further than the laser projection keyboard, a USB or Bluetooth input device consisting of a projector with a sensor to detect finger movements on a projected virtual keyboard. Invented by IBM engineers in 1992 and refined by Canesta, a Korean startup, it is available now for about $150.
I’ll bet you didn’t know there was that much to know about keyboards, did you? And this doesn’t even cover smart phone keyboards, using swype, Gboard, etc. [Maybe you should check out cases (and power supplies), mice, screens, printers and other hardware and see what you might learn there, too!]