The Types of Keyboards

Keyboards and Screen Input Devices By: Sohel Shaikh(17BCE170)

Keyboard is the most common and very popular input device which helps to input data to the computer. The layout of the keyboard is like that of traditional typewriter, although there are some additional keys provided for performing additional functions.Keyboards are of two sizes 84 keys or 101/102 keys, but now keyboards with 104 keys or 108 keys are also available for Windows and Internet.Keyboards can also use a variety of other typing key arrangements. The most widely known is Dvorak, named for its creator, August Dvorak. The Dvorak layout places all of the vowels on the left side of the keyboard and the most common consonants on the right. The most commonly used letters are all found along the home row. The home row is the main row where you place your fingers when you begin typing. People who prefer the Dvorak layout say it increases their typing speed and reduces fatigue. Other layouts include ABCDE, XPeRT, QWERTZ and AZERTY. Each is named for the first keys in the pattern. The QWERTZ and AZERTY arrangements are commonly used in Europe.

Working of a Keyboard: A keyboard is a lot like a miniature computer. It has its own processor and circuitry that carries information to and from that processor. A large part of this circuitry makes up the key matrix.The key matrix is a grid of circuits underneath the keys. In all keyboards (except for capacitive models, which we’ll discuss in the next section), each circuit is broken at a point below each key. When you press a key, it presses a switch, completing the circuit and allowing a tiny amount of current to flow through. The mechanical action of the switch causes some vibration, called bounce, which the processor filters out. If you press and hold a key, the processor recognizes it as the equivalent of pressing a key repeatedly.When the processor finds a circuit that is closed, it compares the location of that circuit on the key matrix to the character map in its read-only memory (ROM).

A character map is basically a comparison chart or lookup table. It tells the processor the position of each key in the matrix and what each keystroke or combination of keystrokes represents. For example, the character map lets the processor know that pressing the a key by itself corresponds to a small letter “a”, but the Shift and a keys pressed together correspond to a capital “A.“A computer can also use separate character maps, overriding the one found in the keyboard. This can be useful if a person is typing in a language that uses letters that don’t have English equivalents on a keyboard with English letters. People can also set their computers to interpret their keystrokes as though they were typing on a Dvorak keyboard even though their actual keys are arranged in a QWERTY layout. In addition, operating systems and applications have keyboard accessibility settings that let people change their keyboard’s behavior to adapt to disabilities.

Types of Keys:

Alphanumeric Keys

This include letters(A-Z) and numbers(0-9).Numeric KeypadIt consists of a set of 17 keys that are laid out in the same configuration used by most adding machines and calculators.

Function Keys

The twelve function keys are present on the keyboard which are arranged in a row at the top of the keyboard. Each function key has a unique meaning and is used for some specific purpose.

Control Keys

These keys provide cursor and screen control. It includes four directional arrow keys. Control keys also include Home, End, Insert, Delete, Page Up, Page Down, Control(Ctrl), Alternate(Alt), Escape(Esc).Special Purpose KeysKeyboard also contains some special purpose keys such as Enter, Shift, Caps Lock, Num Lock, Spacebar, Tab, and Print Screen.

Types of keyboards:Standard, Non Standard, Chorded, Software, Projection Optical Keyboard Technology, Software Keyboards, A virtual keyboard is a software component that allows a user to enter characters. A virtual keyboard can usually be operated with multiple input devices, which may include a touch screen or a computer mouse.

On a desktop computer, a virtual keyboard might provide an alternative input mechanism for users with disabilities who cannot use a conventional keyboard, or for bi- or multilingual users who switch frequently between different character sets or alphabets, which may be confusing over time. Although hardware keyboards are available with dual keyboard layouts (e.g. Cyrillic/Latin letters in various national layouts), the on-screen keyboard provides a handy substitute while working at different stations or on laptops, which seldom come with dual layouts.

Security considerations

Virtual keyboards may be used in some cases to reduce the risk of keystroke logging. Online banking service uses a virtual keyboard for the password entry. It is more difficult for malware to monitor the display and mouse to obtain the data entered via the virtual keyboard, than it is to monitor real keystrokes. However it is possible, for example by recording screenshots at regular intervals or upon each mouse click.The use of an on-screen keyboard on which the user “types” with mouse clicks can increase the risk of password disclosure by shoulder surfing, because:An observer can typically watch the screen more easily (and less suspiciously) than the keyboard, and see which characters the mouse moves to.Some implementations of the on-screen keyboard may give visual feedback of the “key” clicked, e.g. by changing its colour briefly.

This makes it much easier for an observer to read the data from the screen. In the worst case, the implementation may leave the focus on the most recently clicked “key” until the next virtual key is clicked, thus allowing the observer time to read each character even after the mouse starts moving to the next character.A user may not be able to “point and click” as fast as they could type on a keyboard, thus making it easier for the observer.