Wednesday, March 16, 2011

LINUX UBUNTU OPERATING SYSTEM

Ubuntu (operating system)

Ubuntu logo
UbuntuMaverickDesktop.png
Ubuntu 10.10 (Maverick Meerkat)
Company / developer Canonical Ltd. / Ubuntu Foundation
OS family Unix-like
Working state Current
Source model Free and open source software (with exceptions)[1][2]
Initial release 20 October 2004 (2004-10-20)
Latest stable release 10.10 (Maverick Meerkat) / 10 October 2010; 5 months ago[3] (2010-10-10)
Latest unstable release 11.04 (Natty Narwhal) Alpha 3 / 3 March 2011; 12 days ago[4] (2011-03-03)
Available language(s) Multilingual (more than 55)
Update method APT (front-ends available)
Package manager dpkg (front-ends like Synaptic available)
Supported platforms i386, amd64
Kernel type Linux (Monolithic-based Hybrid)
Userland GNU
Default user interface GNOME
License Mainly the GNU GPL and various free software other licenses / plus proprietary binary blobs.[1][2]
Official website ubuntu.com
Ubuntu (pronounced /ʊˈbʊntuː/)[5][6] is a computer operating system based on the Debian GNU/Linux distribution and distributed as free and open source software. It is named after the Southern African philosophy of Ubuntu ("humanity towards others").[7]
With an estimated global usage of more than 12 million users,[8] Ubuntu is designed primarily for desktop use, although netbook and server editions exist as well.[9] Web statistics suggest that Ubuntu's share of Linux desktop usage is about 50%,[10][11] and indicate upward-trending usage as a web server.[12]
Ubuntu is sponsored by the UK-based company Canonical Ltd., owned by South African entrepreneur Mark Shuttleworth. Canonical generates revenue by selling technical support and services tied to Ubuntu, while the operating system itself is entirely free of charge.

Contents

 History and development process

Ubuntu is a fork of the Debian project's codebase. The original aim of the Ubuntu team was to create an easy-to-use (freedom for users rather than freedom for programmers) Linux desktop with new releases scheduled on a predictable six-month basis, resulting in a more frequently updated system.[13][14]
Ubuntu's first release was on 20 October 2004. Since then, Canonical has released new versions of Ubuntu every six months[15] with commitment to support each release for eighteen months by providing security fixes, patches to critical bugs and minor updates to programs. It was decided that every fourth release, issued on a two-year basis, would receive long-term support (LTS).[13] LTS releases are supported for three years on the desktop and five years on the server.[15]
The latest LTS release is Ubuntu 10.04 (Lucid Lynx), released on 29 April 2010, while the latest normal release is Ubuntu 10.10 (Maverick Meerkat), released on 10 October 2010.
Ubuntu packages are based on packages from Debian's unstable branch: both distributions use Debian's deb package format and package management tools (APT and Synaptic). Debian and Ubuntu packages are not necessarily binary compatible with each other, however, and sometimes .deb packages may need to be rebuilt from source to be used in Ubuntu.[16] Many Ubuntu developers are also maintainers of key packages within Debian. Ubuntu cooperates with Debian by pushing changes back to Debian,[17]Ian Murdock, the founder of Debian, has expressed concern about Ubuntu packages potentially diverging too far from Debian to remain compatible.[18] Before release, packages are imported from Debian Unstablefrozen, and packagers then work to ensure that the frozen features interoperate well together. although there has been criticism that this does not happen often enough. In the past, continuously and merged with Ubuntu-specific modifications. A month before release, imports are
Ubuntu is currently funded by Canonical Ltd. On 8 July 2005, Mark Shuttleworth and Canonical Ltd. announced the creation of the Ubuntu Foundation and provided an initial funding of US$10 million. The purpose of the foundation is to ensure the support and development for all future versions of Ubuntu. Mark Shuttleworth describes the foundation as an "emergency fund" (in case Canonical's involvement ends).[19]
On 12 March 2009, Ubuntu announced developer support for 3rd party cloud management platforms, such as for those used at Amazon EC2.[20]

 Features

Ubuntu is composed of many software packages, the vast majority are distributed under a free software license. The only exceptions are some proprietary hardware drivers[21] which are needed to safeguard every individual's freedom to use Ubuntu. The main license used is the GNU General Public LicenseGNU Lesser General Public License (GNU LGPL), explicitly declares that users are free to run, copy, distribute, study, change, develop and improve the software. On the other hand, there is also proprietary software available that can run on Ubuntu. Ubuntu focuses on usability, security and stability.[22] The Ubiquity installer allows Ubuntu to be installed to the hard disk from within the Live CD environment, without the need for restarting the computer prior to installation. Ubuntu also emphasizes accessibility and internationalization to reach as many people as possible. Beginning with 5.04, UTF-8 became the default character encoding,[23] which allows for support of a variety of non-Roman scripts. As a security feature, the sudo tool is used to assign temporary privileges for performing administrative tasks, allowing the root account to remain locked, and preventing inexperienced users from inadvertently making catastrophic system changes or opening security holes.[24] PolicyKit is also being widely implemented into the desktop to further harden[jargon]principle of least privilege. (GNU GPL) which, along with the the system through the
Ubuntu comes installed with a wide range of software that includes OpenOffice, Firefox, EmpathyPidgin in versions before 9.10), Transmission, GIMP (in versions prior to 10.04), and several lightweight games (such as Sudoku and chess). Additional software that is not installed by default can be downloaded and installed using the Ubuntu Software Center[25] or the package manager Synaptic, which come pre-installed. Ubuntu allows networking ports to be closed using its firewall, with customized port selection available. End-users can install Gufw (GUI for Uncomplicated Firewall) and keep it enabled.[26] GNOME (the current default desktop) offers support for more than 46 languages.[27] Ubuntu can also run many programs designed for Microsoft Windows (such as Microsoft Office), through Wine or using a Virtual Machine (such as VMware Workstation or VirtualBox). For the upcoming 11.04 release, Canonical intends to drop the GNOME Shell as the default desktop environment in favor of Unity, a graphical interface it first developed for the netbook edition of Ubuntu.[28] (
Ubuntu, unlike Debian, compiles their packages using gcc features such as PIE and Buffer overflow protection to harden their software.[29] These extra features greatly increase security at the performance expense of 1% in 32 bit and 0.01% in 64 bit.[30]

 System requirements

The desktop version of Ubuntu currently supports the x86 32 bit and 64 bit architectures. Unofficial support is available for the PowerPC,[31] IA-64 (Itanium) and PlayStation 3 architectures (note however that Sony officially removed support for OtherOS on the PS3 with firmware 3.21, released on 1 April 2010), as well as ARM mobile processors (see HTC HD2).[32] A supported GPU is required to enable desktop visual effects.
Current Minimum Requirements[33][34][35] Server Desktop
Processor (x86) with the i686 instruction set[36] 300 MHz 1 GHz
Memory 128 MB 512 MB
Hard Drive (free space) GB 5 GB
Monitor Resolution 640×480 1024×768

Installation

Ubuntu Desktop 10.10 Live CD
Installation of Ubuntu is generally performed with the Live CD. The Ubuntu OS can be run directly from the CD (sometimes with a significant performance loss), allowing a user to "test-drive" the OS for hardware compatibility and driver support. The CD also contains the Ubiquity installer,[37] which then can guide the user through the permanent installation process. CD images of all current and past versions are available for download at the Ubuntu web site.[38] Installing from the CD requires a minimum of 256 MiB of RAM.
Users can download a disk image (.iso) of the CD, which can then either be written to a physical medium (CD or DVD), or optionally run directly from a hard drive (via UNetbootin or GRUB). Ubuntu is also available on ARM, PowerPC, SPARC, and IA-64 platforms, although none are officially supported.[39]
Canonical offers Ubuntu[40] and Kubuntu[41] Live installation CDs at no cost, including paid postage for destinations in most countries around the world (via a service called ShipIt). Various third-party programs such as remastersys and Reconstructor are available to create customised copies of the Ubuntu Live CDs.
A Microsoft Windows migration tool, called Migration Assistant (introduced in April 2007),[42] can be used to import bookmarks, desktop background (wallpaper), and various settings from an existing MS Windows installation into a new Ubuntu installation.[43]
Ubuntu and Kubuntu can be booted and run from a USB Flash drive (as long as the BIOS supports booting from USB), with the option of saving settings to the flashdrive. This allows a portable installation that can be run on any PC which is capable of booting from a USB drive.[44] In newer versions of Ubuntu, the USB creator program is available to install Ubuntu on a USB drive (with or without a LiveCD disc).
Wubi, which is included as an option on the Live CD,[45] allows Ubuntu to be installed and run from within a virtual Windows loop device (as a large image file that is managed like any other Windows program via the Windows Control Panel). This method requires no partitioning of a Windows user's hard drive. Wubi also makes use of the Migration Assistant to import users' settings. It is only useful for Windows users and it also incurs a slight performance loss.

 Package classification and support

Ubuntu divides all software into four domains to reflect differences in licensing and the degree of support available.[46] Some unsupported applications receive updates from community members, but not from Canonical Ltd.

Free software Non-free software
Supported Main Restricted
Unsupported Universe Multiverse
Free software includes only software that has met the Ubuntu licensing requirements,[21] which roughly correspond to the Debian Free Software Guidelines. Exceptions, however, include firmware and fonts, in the Main category, because although they are not allowed to be modified, their distribution is otherwise unencumbered.[citation needed]
Non-free software is usually unsupported (Multiverse), but some exceptions (Restricted) are made for important non-free software. Supported non-free software includes device drivers that can be used to run Ubuntu on some current hardware, such as binary-only graphics card drivers. The level of support in the Restricted category is more limited than that of Main, because the developers may not have access to the source code. It is intended that Main and Restricted should contain all software needed for a general-use GNU/Linux system.[citation needed] Alternative programs for the same tasks and programs for specialized applications are placed in the Universe and Multiverse categories.
In addition to the above, in which the software does not receive new features after an initial release, Ubuntu Backports is an officially recognized repository for backporting newer software from later versions of Ubuntu.[47] The repository is not comprehensive; it consists primarily of user-requested packages, which are approved if they meet quality guidelines. Backports receives no support at all from Canonical, and is entirely community-maintained.
The -updates repository provides updates to stable releases of Ubuntu and are generally installed through update-manager. Each release is given its own -updates repository (e.g. intrepid-updates). The repository is supported by Canonical Ltd. for packages in main and restricted, and by the community for packages in universe and multiverse. All updates to the repository must meet certain requirements and go through the -proposed repository before being made available to the public.[48] Updates will continue to be available until the end of life for the release.
In addition to the -updates repository, the unstable -proposed repository contains uploads which must be confirmed before being copied into -updates. All updates must go through this process to ensure that the patch does truly fix the bug and there is no risk of regression.[49] Updates in -proposed are confirmed by either Canonical or members of the community.
Canonical's partner repository lets vendors of proprietary software deliver their products to Ubuntu users at no cost through the same familiar tools for installing and upgrading software.[50] The software in the partner repository is officially supported with security and other important updates by its respective vendors. Canonical supports the packaging of the software for Ubuntu[50][51][52] and provides guidance to vendors.[50] The partner repository is disabled by default and can be enabled by the user.[53] Some popular products distributed via the partner repository as of August 2010 are Adobe Flash Player, Adobe Reader, Skype and Sun Java.

 Availability of third-party software

Ubuntu has a certification system for third party software.[54] Some third-party software that does not limit distribution is included in Ubuntu's multiverse component. The package ubuntu-restricted-extrasMP3 and DVDMicrosoft TrueType core fonts, Sun's Java runtime environment, Adobe's Flash Playercodecs, and unrar, an unarchiver for files compressed in the RAR file format. additionally contains software that may be legally restricted, including support for playback, plugin, many common audio/video
Additionally, several third party application suites are available for purchase through the Canonical web-based store,[citation needed] including software for DVD playback and media codecs.Releases
Version Code name Release date Supported until
Desktop Server
4.10 Warty Warthog 2004-10-20 2006-04-30
5.04 Hoary Hedgehog 2005-04-08 2006-10-31
5.10 Breezy Badger 2005-10-13 2007-04-13
6.06 LTS Dapper Drake 2006-06-01 2009-07-14 2011-06
6.10 Edgy Eft 2006-10-26 2008-04-25
7.04 Feisty Fawn 2007-04-19 2008-10-19
7.10 Gutsy Gibbon 2007-10-18 2009-04-18
8.04 LTS Hardy Heron 2008-04-24 2011-04 2013-04
8.10 Intrepid Ibex 2008-10-30 2010-04-30
9.04 Jaunty Jackalope 2009-04-23 2010-10-23
9.10 Karmic Koala 2009-10-29 2011-04
10.04 LTS Lucid Lynx 2010-04-29 2013-04 2015-04
10.10 Maverick Meerkat 2010-10-10 2012-04
11.04 Natty Narwhal 2011-04-28 2012-10
11.10 Oneiric Ocelot 2011-10-? 2013-04
Colour Meaning
Red Release no longer supported
Green Release still supported
Blue Future release
Each Ubuntu release has a version number that consists of the year and month number of the release.[55] For example, the first release was Ubuntu 4.10 as it was released on 20 October 2004. Version numbers for future versions are provisional; if the release is delayed the version number changes accordingly.
Ubuntu releases are also given alliterative code names, using an adjective and an animal (e.g., "Dapper Drake" and "Intrepid Ibex"). With the exception of the first three releases, code names are in alphabetical order, allowing a quick determination of which release is newer. "We might skip a few letters, and we'll have to wrap eventually." says Mark Shuttleworth while describing the naming scheme.[citation needed] Commonly, Ubuntu releases are referred to using only the adjective portion of the code name.[56]
Releases are timed to be approximately one month after GNOME releases (which in turn are about one month after releases of X.org). Consequently, every Ubuntu release comes with an updated version of both GNOME and X.
Upgrades between releases have to be done from one release to the next release (e.g. Ubuntu 10.04 to Ubuntu 10.10) or from one LTS release to the next LTS release (e.g. Ubuntu 8.04 LTS to Ubuntu 10.04 LTS).[57]
The current release is 10.10 (Maverick Meerkat), released on 10 October 2010 (10/10/10). This is a departure from the traditional schedule of releasing at the end of October to get "the perfect 10",[58] and a playful reference to The Hitchhiker's Guide to the Galaxy, since, in binary, 101010 is equal to the number 42, the "Answer to the Ultimate Question of Life, the Universe and Everything" within the series.[59]
Ubuntu 11.04 planned for 28 April 2011 is code named "Natty Narwhal".[60][61]

Variants

Kubuntu is an official variant of the Ubuntu distribution which uses the KDE Plasma Workspaces.
Official Ubuntu editions, which are created and maintained by Canonical and the Ubuntu community and receive full support from Canonical, its partners and the Community, are the following:[62][63]
  • Ubuntu Desktop Edition, designed for desktop and laptop PCs.
  • Ubuntu Netbook Edition, (formerly Ubuntu Netbook Remix)[64][65] designed for netbooks and other ultra-portables.[66] Ubuntu Netbook Edition is set to be discontinued, as the Unity Interface will be used as default in both Desktop and Netbook Editions.[67]
  • Ubuntu Server Edition, made for use in servers.[68]
There are many Ubuntu variants (or derivates) based on the official Ubuntu editions. These Ubuntu variants install a set of packages that differ from the official Ubuntu distributions.
The variants recognized by Canonical as contributing significantly towards the Ubuntu project are the following:[62]
  • Edubuntu, a GNOME-based subproject and add-on for Ubuntu, designed for school environments and home users.[69]
  • Kubuntu, a desktop distribution using the KDE Plasma Workspaces desktop environment rather than GNOME.
  • Mythbuntu, designed for creating a home theater PC with MythTV and uses the Xfce desktop environment.
  • Ubuntu Studio, a distribution made for professional video and audio editing, comes with higher-end free editing software and is a DVD .iso image unlike the Live CD the other Ubuntu distributions use.
  • Xubuntu, a distribution based on the Xfce desktop environment instead of GNOME, designed to run more efficiently on low-specification computers.
Mythbuntu, Ubuntu Studio, Xubuntu and Gobuntu are not commercially supported by Canonical.[70]
Other variants are created and maintained by individuals and organizations outside of Canonical and they are self governed projects that work more or less closely with the Ubuntu community.[63] Some of the variants, such as Lubuntu, a lightweight variant using LXDE, have the explicit goal of earning official endorsement from Canonical.[71]

 Development

UDS Maverick Group Photo
The Ubuntu Developer Summit is a gathering of software developers which occurs prior to the release of a new public version of Ubuntu.[72]
At the beginning of a new development cycle, Ubuntu developers from around the world gather to help shape and scope the next release of Ubuntu. The summit is open to the public, but it is not a conference, exhibition or other audience-oriented event. Rather, it is an opportunity for Ubuntu developers, who usually collaborate online, to work together in person on specific tasks.

 Reception

Chris Kenyon, vice president for OEM at Canonical Ltd., indicates that because of a lack of registration, any numbers provided for Ubuntu distributions should be treated as estimates.[73] Nevertheless, a number of estimates and the results of surveys have been provided. In an August 2007 survey of 38,500 visitors on DesktopLinux.com, Ubuntu was the most popular distribution with 30.3% of respondents claiming to use it.[74] In January 2009, The New York Times reported that Ubuntu had over ten million users. In June 2009 ZDNet reported, "Worldwide, there are 13 million active Ubuntu users with use growing faster than any other distribution.",[75][76] though Kenyon provided a more conservative estimate of 12 million users in April 2010.[73]
Ubuntu was awarded the Reader Award for best Linux distribution at the 2005 LinuxWorld Conference and Expo in London,[77] received favorable reviews in online and print publications,[78][79]InfoWorld's 2007 Bossie Award for and has won Best Open Source Client OS.[80] In early 2008 PC World named Ubuntu the "best all-around Linux distribution available today", though it criticized the lack of an integrated desktop effects manager.[81]
The public sector has also made use of Ubuntu. The Ministry of Education and Science of the Republic of Macedonia deployed more than 180,000 Ubuntu GNU/Linux based classroom desktops, and has encouraged every student in the country to use Ubuntu-powered computer workstations.[82] In the beginning of 2008, having successfully deployed 13,000 Fedora Linux systems in schools in the Philippines, ASI, an independent Linux consultant company, was contracted to provide 10,000 Ubuntu systems for schools.[83] The French police, having already started using open source software in 2005 by replacing Microsoft Office with OpenOffice.org in 2005, decided to transition to Ubuntu from Windows XP after the release of Windows Vista in 2006.[84] By March 2009, the Gendarmerie Nationale had already switched 5000 workstations to Ubuntu.[84] Based on the success of that transition, it planned to switch 15,000 more over by the end of 2009 and to have switched all 90,000 workstations over by 2015.[84] Lt. Colonel Guimard announced that the move was very easy and allowed for a 70% saving on the IT budget without having to reduce its capabilities.[84]
In 2008, Jamie Hyneman, co-host of the television series Mythbusters, advocated Linux (specifically giving the example of Ubuntu) as an alternative to proprietary software, citing software bloat as a major hurdle in proprietary operating systems.[85]

 Local Communities (LoCos)

In an effort to reach out to users who are less technical, and to foster a sense of community around the distribution, Local Communities,[86] better known as "LoCos", have been established throughout the world. Originally, each country had one LoCo Team. However, in some areas, most notably, the United States, each state or province may establish a team. A LoCo Council approves teams based upon their efforts to either aid in the development or the promotion of Ubuntu.

 Vendor support

A number of vendors offer computers with Ubuntu pre-installed, including Hasee, Dell,[87] Tesco, OP3, Gliese IT, System76,[88] Sharp Corporation[89] and the South African company Bravium Computers.[90] Dell and System76 customers are able to choose between 30-day, three-month, and yearly Ubuntu support plans through Canonical.[91] Dell computers (running Ubuntu 10.04) include extra support for ATI Video Graphics, Dell Wireless, Fingerprint Readers, HDMI, Bluetooth, DVD Playback (using LinDVD), and MP3/WMA/WMV.[92]

Wednesday, March 2, 2011

KEYBOARD

Computer keyboard

A laptop's keyboard.
In computing, a keyboard is a typewriter keyboard, which uses an arrangement of buttons or keys, to act as mechanical levers or electronic switches. With the decline of punch cards and paper tape, interaction via teletype-style keyboards became the main input device for computers.
Despite the development of alternative input devices, such as the mouse, touchscreen, pen devices, character recognition and voice recognition, the keyboard remains the most commonly used and most versatile device used for direct (human) input into computers.
A keyboard typically has characters engraved or printed on the keys and each press of a key typically corresponds to a single written symbol. However, to produce some symbols requires pressing and holding several keys simultaneously or in sequence. While most keyboard keys produce letters, numbers or signs (characters), other keys or simultaneous key presses can produce actions or computer commands.
In normal usage, the keyboard is used to type text and numbers into a word processor, text editor or other program. In a modern computer, the interpretation of key presses is generally left to the software. A computer keyboard distinguishes each physical key from every other and reports all key presses to the controlling software. Keyboards are also used for computer gaming, either with regular keyboards or by using keyboards with special gaming features, which can expedite frequently used keystroke combinations. A keyboard is also used to give commands to the operating system of a computer, such as Windows' Control-Alt-Delete combination, which brings up a task window or shuts down the machine. It is the only way to enter commands on a command-line interface.

Contents


Keyboard types

One factor determining the size of a keyboard is the presence of duplicate keys, such as a separate numeric keyboard, for convenience.
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. See also text entry interface.
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.

Standard

Standard "full-travel" 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 102/105 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.[1] Computer keyboards are similar to electric-typewriter keyboards but contain additional keys. Standard USB keyboards can also be connected to some non-desktop devices. [2]

Laptop-size

Keyboards on laptops and notebook computers usually have a shorter travel distance for the keystroke 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 keyboards on laptops have a shorter travel distance and (usually) a reduced set of keys.

Thumb-sized

Smaller keyboards have been introduced for laptops (mainly nettops), PDAs, smartphones, or users who have a limited workspace.
A chording keyer allows pressing several keys simultaneously. For example, the GKOS keyboard has been designed for small wireless devices. Other two-handed alternatives more akin to a game controller, such as the AlphaGrip, are also used as a way to input data and text.
A "thumbboard" (thumbing) is used in some personal digital assistants such as the Palm Treo and BlackBerry and some Ultra-Mobile PCs such as the OQO.
Numeric keyboards contain only numbers, mathematical symbols for addition, subtraction, multiplication, and division, a decimal point, and several function keys. They are often used to facilitate data entry with smaller keyboards that do not have a numeric keypad, commonly those of laptop computers. These keys are collectively known as a numeric pad, numeric keys, or a numeric keypad, and it can consist of the following types of keys:
  • arithmetic operators such as +, -, *, /
  • numeric digits 0–9
  • cursor arrow keys
  • navigation keys such as Home, End, PgUp, PgDown, etc.
  • Num Lock button, used to enable or disable the numeric pad
  • enter key.

Non-standard layout and special-use types

Chorded

While other keyboards generally associate one action with each key, chorded keyboards associate actions with combinations of key presses. Since there are many combinations available, chorded keyboards can effectively produce more actions on a board with fewer keys. Court reporters' stenotype machines use chorded keyboards to enable them to enter text much faster by typing a syllable with each stroke instead of one letter at a time. The fastest typists (as of 2007) use a stenograph, a kind of chorded keyboard used by most court reporters and closed-caption reporters. Some chorded keyboards are also made for use in situations where fewer keys are preferable, such as on devices that can be used with only one hand, and on small mobile devices that don't have room for larger keyboards. Chorded keyboards are less desirable in many cases because it usually takes practice and memorization of the combinations to become proficient.

Software

Software keyboards or on-screen keyboards often take the form of computer programs that display an image of a keyboard on the screen. Another input device such as a mouse or a touchscreen can be used to operate each virtual key to enter text. Software keyboards have become very popular in touchscreen enabled cell phones, due to the additional cost and space requirements of other types of hardware keyboards. Microsoft Windows, Mac OS X, and some varieties of Linux include on-screen keyboards that can be controlled with the mouse.

foldable

A foldable keyboard.
Foldable (also called flexible) keyboards are made of soft plastic or silicone which can be rolled or folded on itself for travel.[3] When in use, these keyboards can conform to uneven surfaces, and are more resistant to liquids than standard keyboards. These can also be connected to portable devices and smartphones. Some models can be fully immersed in water, making them popular in hospitals and laboratories, as they can be disinfected.

Projection/laser

Projection keyboards project an image of keys, usually with a laser, onto a flat surface. The device then uses a camera or infrared sensor to "watch" where the user's fingers move, and will count a key as being pressed when it "sees" the user's finger touch the projected image. Projection keyboards can simulate a full size keyboard from a very small projector. Because the "keys' are simply projected images, they cannot be felt when pressed. Users of projected keyboards often experience increased discomfort in their fingertips because of the lack of "give" when typing. A flat, non-reflective surface is also required for the keys to be projected onto. Most projection keyboards are made for use with PDAs due to their small form factor.

Optical keyboard technology

Also known as photo-optical keyboard, light responsive keyboard, photo-electric keyboard and optical key actuation detection technology.
An optical keyboard technology utilizes light emitting devices and photo sensors to optically detect actuated keys. Most commonly the emitters and sensors are located in the perimeter, mounted on a small PCB. The light is directed from side to side of the keyboard interior and it can only be blocked by the actuated keys. Most optical keyboards require at least 2 beams (most commonly vertical beam and horizontal beam) to determine the actuated key. Some optical keyboards use a special key structure that blocks the light in a certain pattern, allowing only one beam per row of keys (most commonly horizontal beam).

Layout

Alphabetic

The 104-key PC US English QWERTY keyboard layout evolved from the standard typewriter keyboard, with extra keys for computing.
The Dvorak Simplified Keyboard layout arranges keys so that frequently used keys are easiest to press, which reduces muscle fatigue when typing common English.
There are a number of different arrangements of alphabetic, numeric, and punctuation symbols on keys. These different keyboard layouts arise mainly because different people need easy access to different symbols, either because they are inputting text in different languages, or because they need a specialized layout for mathematics, accounting, computer programming, or other purposes. The United States keyboard layout is used as default in the currently most popular operating systems: Windows,[4] Mac OS X[5] and Linux.[6][7] Most of the more common keyboard layouts (QWERTY-based and similar) were designed in the era of the mechanical typewriters, so their ergonomics had to be slightly compromised in order to tackle some of the mechanical limitations of the typewriter.
As the letter-keys were attached to levers that needed to move freely, inventor Christopher Sholes developed the QWERTY layout to reduce the likelihood of jamming. With the advent of computers, lever jams are no longer an issue, but nevertheless, QWERTY layouts were adopted for electronic keyboards because they were widely used. Alternative layouts such as the Dvorak Simplified Keyboard are not in widespread use.
The QWERTZ layout is widely used in Germany and much of Central Europe. The main difference between it and QWERTY is that Y and Z are swapped, and most special characters such as brackets are replaced by diacritical characters.
Another situation takes place with “national” layouts. Keyboards designed for typing in Spanish have some characters shifted, to release the space for Ñ ñ; similarly, those for French and other European languages may have a special key for the character Ç ç . The AZERTY layout is used in France, Belgium and some neighbouring countries. It differs from the QWERTY layout in that the A and Q are swapped, the Z and W are swapped, and the M is moved from the right of N to the right of L (where colon/semicolon is on a US keyboard). The digits 0 to 9 are on the same keys, but to be typed the shift key must be pressed. The unshifted positions are used for accented characters.
Keyboards in many parts of Asia may have special keys to switch between the Latin character set and a completely different typing system. In Japan, keyboards often can be switched between Japanese and the Latin alphabet, and the character ¥ (the Yen currency) is used instead of "\"[citation needed]. In the Arab world, keyboards can often be switched between Arabic and Latin characters.
In bilingual regions of Canada and in the French-speaking province of Québec, keyboards can often be switched between an English and a French-language keyboard; while both keyboards share the same QWERTY alphabetic layout, the French-language keyboard enables the user to type accented vowels such as "é" or "à" with a single keystroke. Using keyboards for other languages leads to a conflict: the image on the key does not correspond to the character. In such cases, each new language may require an additional label on the keys, because the standard keyboard layouts do not share even similar characters of different languages (see the example in the figure above).

Key types

Alphanumeric

A Hebrew keyboard lets the user type in both Hebrew and the Latin alphabet.
A Greek keyboard lets the user type in both Greek and the Latin alphabet (Macbook Pro).
Alphabetical, numeric, and punctuation keys are used in the same fashion as a typewriter keyboard to enter their respective symbol into a word processing program, text editor, data spreadsheet, or other program. Many of these keys will produce different symbols when modifier keys or shift keys are pressed. The alphabetic characters become uppercase when the shift key or Caps Lock key is depressed. The numeric characters become symbols or punctuation marks when the shift key is depressed. The alphabetical, numeric, and punctuation keys can also have other functions when they are pressed at the same time as some modifier keys.
The Space bar is a horizontal bar in the lowermost row, which is significantly wider than other keys. Like the alphanumeric characters, it is also descended from the mechanical typewriter. Its main purpose is to enter the space between words during typing. It is large enough so that a thumb from either hand can use it easily. Depending on the operating system, when the space bar is used with a modifier key such as the control key, it may have functions such as resizing or closing the current window, half-spacing, or backspacing. In computer games and other applications the key has myriad uses in addition to its normal purpose in typing, such as jumping and adding marks to check boxes. In certain programs for playback of digital video, the space bar is used for pausing and resuming the playback.

Modifiers

Modifier keys are special keys that modify the normal action of another key, when the two are pressed in combination. For example, <Alt> + <F4> in Microsoft Windows will close the program in an active window. In contrast, pressing just <F4> will probably do nothing, unless assigned a specific function in a particular program. By themselves, modifier keys usually do nothing.
The Ctrl and Alt keys are important modifier keys.
The most widely-used modifier keys include the Control key, Shift key and the Alt key. The AltGr key is used to access additional symbols for keys that have three symbols printed on them. On the Macintosh and Apple keyboards, the modifier keys are the Option key and Command key, respectively. On MIT computer keyboards, the Meta key is used as a modifier and for Windows keyboards, there is a Windows key. Compact keyboard layouts often use a Fn key. "Dead keys" allow placement of a diacritic mark, such as an accent, on the following letter (e.g., the Compose key).
A Space-cadet keyboard has many modifier keys.
The Enter/Return key typically causes a command line, window form or dialog box to operate its default function, which is typically to finish an "entry" and begin the desired process. In word processing applications, pressing the enter key ends a paragraph and starts a new one.

Navigation and typing modes

Navigation keys include a variety of keys which move the cursor to different positions on the screen. Arrow keys are programmed to move the cursor in a specified direction; page scroll keys, such as the 'Page Up and Page Down keys', scroll the page up and down. The Home key is used to return the cursor to the beginning of the line where the cursor is located; the End key puts the cursor at the end of the line. The Tab key advances the cursor to the next tab stop.
The Insert key is mainly used to switch between overtype mode, in which the cursor overwrites any text that is present on and after its current location, and insert mode, where the cursor inserts a character at its current position, forcing all characters past it one position further. The Delete key discards the character ahead of the cursor's position, moving all following characters one position "back" towards the freed place. On many notebook computer keyboards the key labeled Delete (sometimes Delete and Backspace are printed on the same key) serves the same purpose as a Backspace key. The Backspace key deletes the preceding character.
Lock keys lock part of a keyboard, depending on the settings selected. The lock keys are scattered around the keyboard. Most styles of keyboards have three LEDs indicating which locks are enabled, in the upper right corner above the numpad. The lock keys include Scroll lock, Num lock (which allows the use of the numeric keypad), and Caps lock.

System commands

The SysRq / Print screen commands often share the same key. SysRq was used in earlier computers as a "panic" button to recover from crashes. The Print screen command used to capture the entire screen and send it to the printer, but in the present it usually puts a screenshot in the clipboard. The Break key/Pause key no longer has a well-defined purpose. Its origins go back to teletype users, who wanted a key that would temporarily interrupt the communications line. The Break key can be used by software in several different ways, such as to switch between multiple login sessions, to terminate a program, or to interrupt a modem connection.
In programming, especially old DOS-style BASIC, Pascal and C, Break is used (in conjunction with Ctrl) to stop program execution. In addition to this, Linux and variants, as well as many DOS programs, treat this combination the same as Ctrl+C. On modern keyboards, the break key is usually labeled Pause/Break. In most Windows environments, the key combination Windows key+Pause brings up the system properties.
The Escape key (often abbreviated Esc) is used to initiate an escape sequence. As most computer users no longer are concerned with the details of controlling their computer's peripherals, the task for which the escape sequences were originally designed, the escape key was appropriated by application programmers, most often to "escape" or back out of a mistaken command. This use continues today in Microsoft Windows's use of escape as a shortcut in dialog boxes for No, Quit, Exit, Cancel, or Abort.
A common application today of the Esc key is as a shortcut key for the Stop button in many web browsers. On machines running Microsoft Windows, prior to the implementation of the Windows key on keyboards, the typical practice for invoking the "start" button was to hold down the control key and press escape. This process still works in Windows 2000, XP, Windows Vista and Windows 7.
The Menu key or Application key is a key found on Windows-oriented computer keyboards. It is used to launch a context menu with the keyboard rather than with the usual right mouse button. The key's symbol is a small icon depicting a cursor hovering above a menu. This key was created at the same time as the Windows key. This key is normally used when the right mouse button is not present on the mouse. Some Windows public terminals do not have a Menu key on their keyboard to prevent users from right-clicking (however, in many windows applications, a similar functionality can be invoked with the Shift+F10 keyboard shortcut).

Miscellaneous

Multimedia buttons on some keyboards give quick access to the Internet or control the volume of the speakers.
Many, but not all, computer keyboards have a numeric keypad to the right of the alphabetic keyboard which contains numbers, basic mathematical symbols (e.g., addition, subtraction, etc.), and a few function keys. On Japanese/Korean keyboards, there may be Language input keys. Some keyboards have power management keys (e.g., Power key, Sleep key and Wake key); Internet keys to access a web browser or E-mail; and/or multimedia keys, such as volume controls.

Multiple Layouts

It possible to install multiple keyboard layout and switch among them in computer with the help of either operating system or application program. Microsoft Windows[8], Ubuntu[9], Linux[10], Mac[11] provide support to add keyboard layouts and choose from them.

Layout changing software

Depending on operating systems, various application programs are available to create, add and switch among keyboard layouts. For example, Ukelele for Mac, The Microsoft Keyboard Layout Creator[12] and open source Avro Keyboard for Windows provide the ability to customize the keyboard layout as desired. Many other similar softwares[13] are available, some of which are language specific.

Illumination

Keyboards and keypads may be illuminated from inside, especially on equipment for mobile use. Illumination facilitates the use of the keyboard or keypad in dark environments. Some gaming keyboards have lighted keys, to make it easier for gamers to find command keys while playing in a dark room. Some computers may have small LED lights in a few important function keys, to remind users that the function is activated (see photo).
Keys with integrated LED indicator lights

Technology

Key switches

In the first electronic keyboards in the early 1970s, the key switches were individual switches inserted into holes in metal frames. These keyboards cost from 80–120 US dollars and were used in mainframe data terminals. The most popular switch types were reed switches (contacts enclosed in a vacuum in a glass capsule, affected by a magnet mounted on the switch plunger – from Clare-Pendar in Post Falls Idaho, which became part of General Instrument, which used reedswitch capsules made by C.P. Clare Co. in Illinois; and Key Tronic Corporation of Spokane, Washington), Hall-effect switches (using a Hall-effect semiconductor where a current is generated by a passing magnet – from Microswitch in Illinois, which became part of Honeywell), and inductive core switches (again, activated by a magnet – from Cortron, which was part of ITW/Illinois Tool Works). These switches were rated to last for 100 million cycles and had 0.187-inch (4.75 mm) key travel, compared to 0.110 inch (2.79 mm) today.
In the mid 1970's, lower-cost direct-contact key switches were introduced, but their life in switch cycles was much shorter (rated ten million cycles) because they were open to the environment. This became more acceptable, however, for use in computer terminals at the time, which began to see increasingly shorter model lifespans as they advanced.
In 1978, Key Tronic Corporation introduced keyboards with capacitive-based switches, one of the first keyboard technologies to not use self-contained switches. There was simply a sponge pad with a conductive-coated Mylar plastic sheet on the switch plunger, and two half-moon trace patterns on the printed circuit board below. As the key was depressed, the capacitance between the plunger pad and the patterns on the PCB below changed, which was detected by IC's/Integrated Circuits. These keyboards were claimed to have the same reliability as the other "solid-state switch" keyboards such as inductive and Hall-Effect, but competitive with direct-contact keyboards. Prices of $60 for keyboards were achieved and Key Tronic rapidly became the largest independent keyboard manufacturer.
Meanwhile, IBM made their own keyboards, using their own patented technology: Keys on older IBM keyboards were made with a "buckling spring" mechanism, in which a coil spring under the key buckles under pressure from the user's finger, pressing a rubber dome, whose inside is coated with conductive graphite, which connects two leads below, completing a circuit. This produces a clicking sound, and gives physical feedback for the typist indicating that the key has been depressed.[14][15]
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 which was only about one inch thick. And now keyboards measure only about a half-inch thick.
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 names/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. 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 than standard ABS keytop plastic material.
Three final mechanical technologies brought keyboards to where they are today, driving the cost well under $10:
  1. "Monoblock" keyboard designs were developed where individual switch housings were eliminated and a one-piece "monoblock" housing used instead. This was possible because of molding techniques that could provide very tight tolerances for the switch-plunger holes and guides across the width of the keyboard so that the key plunger-to-housing clearances were not too tight or too loose, either of which could cause the keys to bind.
  2. The use of contact-switch membrane sheets under the monoblock. This technology came from flat-panel switch membranes, where the switch contacts are printed inside of a top and bottom layer, with a spacer layer in between, so that when pressure is applied to the area above, a direct electrical contact is made. The membrane layers can be printed by very-high volume, low-cost "reel-to-reel" printing machines, with each keyboard membrane cut and punched out afterwards.
  3. The use of pad-printed keytops (called "Tampo printed" at the time because Tampo was the most popular equipment manufacturer). Initially sublimation ink was used (see above), but very durable clear-coats are now printed over the key legends to protect them. These coatings are also used to reduce glare, and in many cases have an anti-microbial content added for user protection.[16]
Plastic materials played a very important part in the development and progress of electronic keyboards. Until "monoblocks" came along, GE's "self-lubricating" Delrin was the only plastic material for keyboard switch plungers that could withstand the beating over tens of millions of cycles of lifetime use. Greasing or oiling switch plungers was undesirable because it would attract dirt over time which would eventually affect the feel and even bind the key switches (although keyboard manufacturers would sometimes sneak this into their keyboards, especially if they could not control the tolerances of the key plungers and housings well enough to have a smooth key depression feel or prevent binding). But Delrin was only available in black and white, and was not suitable for keytops (too soft), so keytops use ABS plastic. However, as plastic molding advanced in maintaining tight tolerances, and as key travel length reduced from 0.187-inch to 0.110-inch (4.75 mm to 2.79 mm), single-part keytop/plungers could be made of ABS, with the keyboard monolocks also made of ABS.

Control processor

Computer keyboards include control circuitry to convert key presses into key codes that the computer's electronics can understand. The key switches are connected via the printed circuit board in an electrical X-Y matrix where a voltage is provided sequentially to the Y lines and, when a key is depressed, detected sequentially by scanning the X lines.
The first computer keyboards were for mainframe computer data terminals and used discrete electronic parts. The first keyboard microprocessor was introduced in 1972 by General Instruments, but keyboards have been using the single-chip 8048 microcontroller variant since it became available in 1978. The keyboard switch matrix is wired to its inputs, it converts the keystrokes to key codes, and, for a detached keyboard, sends the codes down a serial cable (the keyboard cord) to the main processor on the computer motherboard. This serial keyboard cable communication is only bi-directional to the extent that the computer's electronics controls the illumination of the "caps lock", "num lock" and "scroll lock" lights.
One test for whether the computer has crashed is pressing the "caps lock" key. The keyboard sends the key code to the keyboard driver running in the main computer; if the main computer is operating, it commands the light to turn on. All the other indicator lights work in a similar way. The keyboard driver also tracks the shift, alt and control state of the keyboard.
Some lower-quality keyboards have multiple or false key entries due to inadequate electrical designs. These are caused by inadequate keyswitch "debouncing" or inadequate keyswitch matrix layout that don't allow multiple keys to be depressed at the same time, both circumstances which are explained below:
When pressing a keyboard key, the key contacts "bounce" against each other several times for several milliseconds before they settle into firm contact (although this was not true with early "solid-state" keyswitch keyboards that used Hall-effect, inductive, or capacitive keyswitch technologies). When released, they bounce some more until they revert to the uncontacted state. If the computer were watching for each pulse, it would see many keystrokes for what the user thought was just one. To resolve this problem, the processor in a keyboard (or computer) "debounces" the keystrokes, by aggregating them across time to produce one "confirmed" keystroke that (usually) corresponds to what is typically a solid contact.
Some low-quality keyboards also suffer problems with rollover (that is, when multiple keys pressed at the same time, or when keys are pressed so fast that multiple keys are down within the same milliseconds). Early "solid-state" keyswitch keyboards did not have this problem because the keyswitches are electrically isolated from each other, and early "direct-contact" keyswitch keyboards avoided this problem by having isolation diodes for every keyswitch. So, these early keyboards had "n-key" rollover, which means any number of keys can be depressed and the keyboard will still recognize the next key depressed. But when three keys are pressed (electrically closed) at the same time in a "direct contact" keyswitch matrix that doesn't have isolation diodes (diode are not practical with current membrane-switch based keyboards), the keyboard electronics can see a fourth "phantom" key which is the intersection (shorting out) of the X and Y lines of the three keys. Some types of keyboard circuitry will register a maximum number of keys at one time, such as "three-key" rollover maximum, also called "phantom key blocking" or "phantom key lockout", meaning that it will only register three keys and ignore all others until one of the three keys is lifted. This is of course undesirable, especially for fast typing (hitting new keys before the fingers can release previous keys, and undesirable for games (designed for multiple key presses).
As direct-contact membrane keyboards became popular, the available rollover of keys was optimized by analyzing the most common key sequences and placing these keys so that they do not potentially produce phantom keys in the electrical key matrix (for example, simply placing three or four keys that might be depressed simultaneously on the same X or same Y line, so that a phantom key intersection/short cannot happen), so that blocking a third key usually isn't a problem. But lower-quality keyboard designs and unknowledgeable engineers may not know these tricks, and it can still be a problem in games due to wildly different and/or configurable key/command layouts in different games.

Connection types

There are several ways of connecting a keyboard to a system unit (more precisely, to its keyboard controller) using cables, including the standard AT connector commonly found on motherboards, which was eventually replaced by the PS/2 and the USB connection. Prior to the iMac line of systems, Apple used the proprietary Apple Desktop Bus for its keyboard connector.
Wireless keyboards have become popular for their increased user freedom. A wireless keyboard often includes a required combination transmitter and receiver unit that attaches to the computer's keyboard port (see Connection types above). The wireless aspect is achieved either by radio frequency (RF) or by infrared (IR) signals sent and received from both the keyboard and the unit attached to the computer. A wireless keyboard may use an industry standard RF, called Bluetooth. With Bluetooth, the transceiver may be built into the computer. However, a wireless keyboard needs batteries to work and may pose a security problem due to the risk of data "eavesdropping" by hackers. An early example of a consumer wireless keyboard is that of the Olivetti Envision.

Alternative text-entering methods

An on-screen keyboard controlled with the mouse can be used by users with limited mobility.
Optical character recognition (OCR) is preferable to rekeying for converting existing text that is already written down but not in machine-readable format (for example, a Linotype-composed book from the 1940s). In other words, to convert the text from an image to editable text (that is, a string of character codes), a person could re-type it, or a computer could look at the image and deduce what each character is. OCR technology has already reached an impressive state (for example, Google Book Search) and promises more for the future.
Speech recognition converts speech into machine-readable text (that is, a string of character codes). The technology has already reached an impressive state and is already implemented in various software products. For certain uses (e.g., transcription of medical or legal dictation; journalism; writing essays or novels) it is starting to replace the keyboard; however, it does not threaten to replace keyboards entirely anytime soon. It can, however, interpret commands (for example, "close window" or "undo that") in addition to text. Therefore, it has theoretical potential to replace keyboards entirely (whereas OCR replaces them only for a certain kind of task).
Pointing devices can be used to enter text or characters in contexts where using a physical keyboard would be inappropriate or impossible. These accessories typically present characters on a display, in a layout that provides fast access to the more frequently used characters or character combinations. Popular examples of this kind of input are Graffiti, Dasher and on-screen virtual keyboards.

Other issues

Keystroke hacking

Keystroke logging (often called keylogging) is a method of capturing and recording user keystrokes. While it is used legally to measure employee productivity on certain clerical tasks, or by law enforcement agencies to find out about illegal activities, it is also used by hackers for various illegal or malicious acts. Hackers use keyloggers as a means to obtain passwords or encryption keys and thus bypass other security measures.
Keystroke logging can be achieved by both hardware and software means. Hardware key loggers are attached to the keyboard cable or installed inside standard keyboards. Software keyloggers work on the target computer’s operating system and gain unauthorized access to the hardware, hook into the keyboard with functions provided by the OS, or use remote access software to transmit recorded data out of the target computer to a remote location. Some hackers also use wireless keylogger sniffers to collect packets of data being transferred from a wireless keyboard and its receiver, and then they crack the encryption key being used to secure wireless communications between the two devices.
Anti-spyware applications are able to detect many keyloggers and cleanse them. Responsible vendors of monitoring software support detection by anti-spyware programs, thus preventing abuse of the software. Enabling a firewall does not stop keyloggers per se, but can possibly prevent transmission of the logged material over the net if properly configured. Network monitors (also known as reverse-firewalls) can be used to alert the user whenever an application attempts to make a network connection. This gives the user the chance to prevent the keylogger from "phoning home" with his or her typed information. Automatic form-filling programs can prevent keylogging entirely by not using the keyboard at all. Most keyloggers can be fooled by alternating between typing the login credentials and typing characters somewhere else in the focus window.[17]

Wireless keystroke hacking

Also known as remote keylogging or wireless keylogging.
In their research “Compromising Electromagnetic Emanations of Wired Keyboard”[18] Vuagnoux and Pasini have provided evidence that modern keyboards radiate compromising electromagnetic emanations. The four techniques presented in their paper prove that these basic devices are generally not sufficiently protected against compromising emanations. Additionally, they showed that these emanations can be captured with relatively inexpensive equipment and keystrokes are recovered[19] not only in the semi-anechoic chamber but in practical environments as well (e.g office). The consequences of these attacks are that compromising electromagnetic emanations of keyboards still represent a security risk. PS/2, USB, laptop and wireless keyboards are vulnerable. Moreover, there is no software patch to avoid these attacks. Hardware has to be replaced in order to obtain safe devices. Due to cost pressure in the design and lack of knowledge, manufacturers do not systematically protect keyboards. Even in the practical space of an office with multiple keyboards, Vuagnoux and Pasini were able to deduce a specific fingerprint for every keyboard. When multiple keyboards are radiating at the same time, they are able to identify and differentiate them.

Physical injury

Proper ergonomic design of computer keyboard desks is necessary to prevent repetitive strain injuries, which can develop over time and can lead to long-term disability.[20]
The use of any keyboard may cause serious injury (that is, carpal tunnel syndrome or other repetitive strain injury) to hands, wrists, arms, neck or back. The risks of injuries can be reduced by taking frequent short breaks to get up and walk around a couple of times every hour. As well, users should vary tasks throughout the day, to avoid overuse of the hands and wrists. When inputting at the keyboard, a person should keep the shoulders relaxed with the elbows at the side, with the keyboard and mouse positioned so that reaching is not necessary. The chair height and keyboard tray should be adjusted so that the wrists are straight, and the wrists should not be rested on sharp table edges. Wrist or palm rests should not be used while typing.
Some adaptive technology ranging from special keyboards, mouse replacements and pen tablet interfaces to speech recognition software can reduce the risk of injury. Pause software reminds the user to pause frequently. Switching to a much more ergonomic mouse, such as a vertical mouse or joystick mouse may provide relief. Switching from using a mouse to using a stylus pen with graphic tablet or a trackpad can lessen the repetitive strain on the arms and hands.