GadgetWorld

The PlayStation (abbreviated PS, PSone, PS1, or informally as PSX) is a 32-bit fifth generation video game console released by Sony Computer Entertainment in December 1994.

The PlayStation was the first of the ubiquitous PlayStation series of console and handheld game devices. Successor consoles and upgrades include the Net Yaroze, PS one, PocketStation, PlayStation 2, a revised slimline PlayStation 2, PlayStation Portable, a revised PlayStation Portable Slim and Lite, PSX, and the PlayStation 3. On March 31 2005, the PlayStation and PS one reached a combined total of 102.49 million units shipped, becoming the first video game console to reach the 100 million mark.As of July 20, 2008, the PlayStation has sold 102 million units.Sony ceased production of the PlayStation on March 23, 2006, over 11 years since it was first produced.

Manufacturer Sony Computer Entertainment
Product family PlayStation
Type Video game console
Generation Fifth generation era
First available JP December 3, 1994[1]
NA September 9, 1995[2]
EU September 29, 1995[3]
AUS November 1995[4]
CPU MIPS R3000A at 33.8688 MHz.
Media CD-ROM
System storage Memory card
Units sold 102 million (as of July 20, 2008)[5]
Units shipped 102.49 million, including 28.15 million PS one units (as of March 31 2005)[6]
Best-selling game Gran Turismo, 10.85 million shipped (as of April 30 2008)[7][8]
Successor PlayStation 2


The first conceptions of the PlayStation date back to 1986. Nintendo had been attempting to work with disc technology since the Famicom, but the medium had problems. Its rewritable magnetic nature could be easily erased (thus leading to a lack of durability), and the discs were a copyright infringement danger. Consequently, when details of CDROM/XA (an extension of the CD-ROM format that combines compressed audio, visual and computer data, allowing all to be accessed simultaneously) came out, Nintendo was interested. CD-ROM/XA was being simultaneously developed by Sony and Philips. Nintendo approached Sony to develop a CD-ROM add-on, tentatively titled the "SNES-CD". A contract was signed, and work began. Nintendo's choice of Sony was due to a prior dealing: Ken Kutaragi, the person who would later be dubbed "The Father of PlayStation", was the individual who had sold Nintendo on using the Sony SPC-700 processor for use as the eight-channel ADPCM sound synthesis set in the Super Famicom/SNES console through an impressive demonstration of the processor's capabilities.[11]

Sony also planned to develop another, Nintendo compatible, Sony-branded console, but one which would be more of a home entertainment system playing both Super Nintendo cartridges and a new CD format which Sony would design. This was also to be the format used in SNES-CD discs, giving a large degree of control to Sony despite Nintendo's leading position in the video gaming market.
The DualShock controller.
The DualShock controller.

The SNES-CD was to be announced at the June 1991 Consumer Electronics Show (CES). However, when Hiroshi Yamauchi read the original 1988 contract between Sony and Nintendo, he realized that the earlier agreement essentially handed Sony complete control over any and all titles written on the SNES CD-ROM format. Yamauchi decided that the contract was totally unacceptable and he secretly canceled all plans for the joint Nintendo-Sony SNES CD attachment. Instead of announcing a partnership between Sony and Nintendo, at 9 a.m. the day of the CES, Nintendo chairman Howard Lincoln stepped onto the stage and revealed that Nintendo was now allied with Philips, and Nintendo was planning on abandoning all the previous work Nintendo and Sony had accomplished. Lincoln and Minoru Arakawa had, unbeknown to Sony, flown to Philips headquarters in Europe and formed an alliance of a decidedly different nature—one that would give Nintendo total control over its licenses on Philips machines.

After the collapse of the joint project, Sony considered halting their research, but ultimately the company decided to use what they had developed so far and make it into a complete, stand alone console. As a result, Nintendo filed a lawsuit claiming breach of contract and attempted, in U.S. federal court, to obtain an injunction against the release of the PlayStation, on the grounds that Nintendo owned the name. The federal judge presiding over the case denied the injunction and, in October 1991, the first incarnation of the new Sony PlayStation was revealed. However, it is theorized that only 200 or so of these machines were ever produced.
PlayStation Memory Card.
PlayStation Memory Card.

By the end of 1992, Sony and Nintendo reached a deal whereby the "Sony Play Station" would still have a port for SNES games, but Nintendo would own the rights and receive the bulk of the profits from the games, and the SNES would continue to use the Sony-designed audio chip. However, Sony decided in early 1993 to begin reworking the "Play Station" concept to target a new generation of hardware and software. As part of this process the SNES cartridge port was dropped and the space between the names was removed.

Launch

The PlayStation was launched in Japan on December 3, 1994, North America on September 9, 1995, Europe on September 29, 1995, and Oceania in November 1995. The launch price in the American market was US$299 (a price point later used by its successor, the PlayStation 2), and Sony enjoyed a very successful launch with titles of almost every genre, including Battle Arena Toshinden, Twisted Metal, Tekken, Warhawk, Air Combat, Philosoma, and Ridge Racer. Almost all of Sony's and Namco's launch titles went on to spawn numerous sequels.

The PlayStation was also able to generate interest with a unique series of advertising campaigns. Many of the ads released at the time of launch were full of ambiguous content which had many gamers rabidly debating their meanings. The most well-known launch ads include the "Enos Lives" campaign, and the "U R Not e" ads (the "e" in "U R Not e" was always colored in red, to symbolize the word "ready", and the "Enos" meant "ready Ninth Of September", the U.S. launch date). The Enos ad could also be read as Sony written backward with phonetic sound of "E" replacing the "y". It is believed that these ads were an attempt to play off the gaming public's suspicion towards Sony as an unknown, untested entity in the video game market. The PlayStation 3 slogan, "PLAY B3YOND", resembles this slogan, as the 3 is red.

The PlayStation logo was designed by Ryan Harrington,[citation needed] who also designed the logo for Sony's VAIO computer products.

The Xbox 360 is the second video game console produced by Microsoft, and was developed in cooperation with IBM, ATI, and SiS. The integrated Xbox Live service allows players to compete online and download content such as arcade games, game demos, trailers, TV shows, and movies. The Xbox 360 is the successor to the Xbox, and competes with Sony's PlayStation 3 and Nintendo's Wii as part of the seventh generation of video game consoles.

The Xbox 360 was officially unveiled on MTV on May 12, 2005, with detailed launch and game information divulged later that month at the Electronic Entertainment Expo (E3). The console sold out completely at release in all regions except in Japan,[4][5][6] and, as of July 17, 2008, 20 million units have been sold worldwide according to Microsoft.[1][2] The Xbox 360 comes in three different versions: the "Arcade" console, the "Premium" console, and the "Elite" console, each having its own selection of included and available accessories. Another version of the Xbox 360, called the "Core" which was available from launch, has since been discontinued for retail and replaced with the "Arcade".






Manufacturer Microsoft
Product family Xbox
Type Video game console
Generation Seventh generation era
First available November 22, 2005 (details)
CPU 3.2 GHz PowerPC Tri-Core Xenon
GPU 500 MHz ATI Xenos
Media DVD, CD,
Add-on: HD DVD (discontinued)
System storage 20, 60 or 120 GB hard drive, 64, 256 or 512 MB memory cards
Controller input 4 maximum (wired or wireless or combination of either)
Connectivity 3 × USB 2.0, IR port, 100 Mbit Ethernet, Add-on: Wifi 802.11a/b/g
Online service Xbox Live
Units sold Worldwide: 20 million (as of July 17, 2008)[1][2] (details)
Best-selling game Halo 3, 8.1 million (as of January 3, 2008)[3]
Backward
compatibility 465 original Xbox games (requires hard drive and the latest update)
Predecessor Xbox


Development

Known during development as Xenon, Xbox 2, Xbox FS,[7] Xbox Next, or NextBox, the Xbox 360 was conceived in early 2003.[8] In February 2003, planning for the Xenon software platform began, and was headed by Microsoft's Vice President J Allard.[8] That month, Microsoft held an event for 400 developers in Bellevue, Washington, to recruit support for the system.[8] Also that month, Peter Moore, former president of Sega of America, joined Microsoft. On August 12, 2003, ATI signed on to produce the graphic processing unit for the new console, a deal which was publicly announced two days later.[9] The following month, IBM agreed to develop the triple-core CPU for the console.[8] Before the launch of the Xbox 360, several alpha development kits were spotted using Apple's Power Mac G5 hardware. This was due to the system's PowerPC 970 processor running the same PowerPC architecture that the Xbox 360 would eventually run under IBM's Xenon processor.

Launch

Main article: Xbox 360 launch

The Xbox 360 was released on November 22, 2005, in the United States and Canada; December 2, 2005, in Europe and December 10, 2005, in Japan. It was later launched in Malaysia, Mexico, Colombia, South Korea, Hong Kong, Singapore, Taiwan, Australia, New Zealand, South Africa, Chile, India, Brazil, Poland, Czech Republic, and Russia. Microsoft has additionally announced official launches in: Hungary, Slovakia,[10] and the Philippines.[11][dead link] In its first year on the market, the system launched in 36 countries, more countries than any console has launched in a single year.[12] Due to its early launch, the Xbox 360 was launched a year before PlayStation 3 and Wii.

Retail configurations

The Xbox 360 is available in three standard variants; the "Xbox 360 Arcade", the "Xbox 360 Premium", and the "Xbox 360 Elite".[13] A discontinued SKU, the "Xbox 360 Core", was replaced by the "Xbox 360 Arcade" in October 2007.[14] The 60 GB version of the Xbox 360 Premium was released on August 1, 2008.

At launch, the Xbox 360 was available in two configurations: the "Xbox 360 Premium" package, priced at US$399 or GB£280 , and the "Xbox 360 Core", priced at US$299 and GB£199. The original shipment of the Premium version included a cut-down version of the Media Remote as a promotion. The Elite package was launched later at US$479.

* The Xbox 360 Core[15] was an entry level Xbox 360 priced at US$279.99. The "Core" is no longer being sold, being replaced by the Xbox 360 Arcade.[13] It was not originally available in Japan, but was later released on November 2, 2006.[16] The Core system came bundled with composite video cables, capable of only SDTV resolutions, but newer models with lot number 0728 or greater have an HDMI 1.2 output. The Core may output HD signals up to 1080p when connected to separately sold HDMI, Component, or VGA cables. It may also utilize a separately sold 20 or 120 GB hard drive. Unlike all other SKUs, it shipped with a wired version of the Xbox 360 controller, instead of the wireless version found in other SKUs.

Xbox 360 Arcade
Xbox 360 Arcade

* The Xbox 360 Arcade,[17] priced at US$199.99,[18] is the replacement for the "Xbox 360 Core".[19] It was publicly revealed (though it was available in stores far earlier)[17] by Microsoft's president of Entertainment Devices division Robbie Bach to the Financial Times on October 18, 2007,[18] and officially announced on October 22, 2007.[14] It includes a wireless controller, 256 MB memory unit, composite AV cable, HDMI 1.2 output, and 5 Xbox Live Arcade titles.[20] The consoles, identified by packaging labeled "Go Play!", are bundled with Boom Boom Rocket, Feeding Frenzy, Luxor 2, Pac-Man Championship Edition, and Uno on a single disk, which also includes a "Welcome Video" and several game trailers/demos.[21]

* The Xbox 360, commonly called the Premium or Pro, currently priced at US$299.99,[22] includes all the features of the Xbox 360 Core and includes a hybrid composite and component cable with optional optical out instead of a composite cable. The Xbox 360 also includes a detachable 20 GB Hard Disk Drive to store downloaded content, provide compatibility with original Xbox games, and store game data. The included hard drive comes with game demos, video clips and a free Live Arcade game, Hexic HD. In July 2007, this version of the Xbox 360 began appearing with the Zephyr motherboard (the motherboard used in the Elite) which features HDMI 1.2 output and an improved GPU heatsink. Although the Premium package does include an HDMI 1.2 output, it does not come with HDMI 1.2 cables.[23][24] Starting at the end of September 2007, the newest systems were shipped with the new "Falcon" motherboard. This motherboard includes the new 65-nm CPUs, making them quieter and cooler than the older systems.[25] Holiday 2007 consoles, with packaging labeled "Go Big", were bundled with Marvel: Ultimate Alliance and Forza Motorsport 2.[26] This bundle has since been discontinued.[13] On August 1, 2008, the 20 GB Premium Xbox 360 was discontinued and was replaced by a 60 GB HDD model at US$349.99 for about a month until the price was cut to US$299.99.[27]

Xbox 360 Elite
Xbox 360 Elite

* The Xbox 360 Elite is the fourth and most expensive variation of the console. It is priced at US$399.99 and includes a 120 GB hard drive and a matte black finish. The Elite retail package also includes an HDMI 1.2 cable and a controller and headset that match the system's black finish.[28] The initial release price was US$479.99,[29] C$549.99,[29] £299.99, and AU$729.95. The Elite was released in Europe on August 24, 2007, and Australia on August 30, 2007. Holiday 2007 consoles, with packaging labeled "Go Big", were bundled with Marvel: Ultimate Alliance and Forza Motorsport 2.[26] This bundle has since been discontinued.[13] Early Elite models shipped using the Zephyr motherboard, though newer models now use the Falcon 65nm chipset instead. These Elites (and other Xbox 360 models using the Falcon) can be identified from earlier versions by a re-designed power connector and a power supply that runs at 175w. The motherboard layout is also different.

Hardware and accessories

Hardware

The main unit of the Xbox 360 itself has slight double concavity in matte white or black. It features a port on the top (when vertical, left side when horizontal) to which a custom-housed hard drive unit can be attached in sizes of either 20, 60 (August 2008 onward) or 120 GB. Inside, the Xbox 360 uses the triple-core IBM designed Xenon as its CPU. Graphics processing is handled by the ATI Xenos which has 10 MB of eDRAM. Its main memory pool is 512 MB in size.

Accessories

Many accessories are available for the console, including both wired and wireless controllers, faceplates for customization, headsets for chatting, a webcam for video chatting, Dance Mats and Gamercize for exercise, three sizes of memory cards, and three sizes of hard drives (120GB, 60GB, and 20GB), among other items, all of which are styled to match the console.

Software

The Xbox 360's graphical user interface is the Xbox 360 Dashboard; a tabbed interface that features five "Blades" (formerly four blades), and was designed by AKQA. It can be launched automatically when the console boots up without a disc, or when the disc tray is ejected. However, the user may choose to launch a game automatically if a disc is inserted. A simplified version of it can also be accessed at any time via the Xbox Guide button on the gamepad. This simplified version shows the user's gamercard, Xbox Live messages and friends list. It also allows for personal and music settings, in addition to voice or video chats, or returning to the primary Dashboard from the game.

Since the console's release, Microsoft has released several updates for the Dashboard software. These updates have included adding new features to the console, enhancing Xbox Live functionality and multimedia playback cabilities, adding compatibility for new accessories, and fixing bugs in the software. The latest Dashboard update, revision 2.0.6717.0, was made available on August 6, 2008.

New Xbox Experience

Further information: Xbox Live#The New Xbox Experience

At E3 2008, at Microsoft's Show, Microsoft's Aaron Greenberg and Marc Whitten announced the new look Xbox 360 called "The New Xbox Experience". The idea of the update is to allow people who cannot navigate the current Blade GUI, to navigate throughout the console easily. The GUI uses the Twist UI (used in Windows Media Center, Zune). The Blade interface is still used in the new Xbox Guide. The new guide allows you to do everything you could do from the Dashboard itself, whether it's ejecting a disk or browsing the Marketplace, thus making it easier to navigate throughout the system.

As well as a GUI update, many new features have been put into the system's software. Firstly, the update offers the ability to install games from the disk to the hard drive, theoretically reducing load times and disk drive noise. However, the game's disk must remain in the system to run its installed version. A new Community system is also built in, allowing the creation of digitalised Avatars. These Avatars can then be used for multiple activities such as sharing photos or playing Arcade games like 1 vs. 100. The update will be released on November 19, 2008.[33]

Multimedia
Xbox 360 Wireless Controller
Xbox 360 Wireless Controller

The Xbox 360 supports videos in .wmv-format, as well as high-definition .wmv-videos, H.264, MPEG-4, and PlaysForSure WMV videos. The December 2007 dashboard update added support for the playback of MPEG-4 ASP format videos.[43] The console can also display pictures and perform slideshows of photo collections with various transition effects, and supports audio playback, with music player controls accessible through the Xbox 360 Guide button. Users may play back their own music while playing games or using the dashboard, and can play music with an interactive visual synthesizer.

Music, photos and videos can be played from standard USB mass storage devices, Xbox 360 proprietary storage devices (such as memory cards or Xbox 360 hard drives), and servers or computers with Windows Media Center or Windows XP with Service Pack 2 or higher within the local-area network in streaming mode.[44][45] This is possible with video files up to HD-resolution and with several codecs (MPEG-2, MPEG-4, WMV) and container formats (WMV, MOV, TS).[46]

In the UK the Xbox 360 will be enabled to download and display BT Vision video content. [47]

XNA community

XNA Community is a future feature where Xbox 360 owners can receive community created XNA Creators Club developed games made with Microsoft XNA Game Studio. The games are written, published, and distributed through a community managed portal. XNA Community will be a channel for console videogame delivery over Xbox Live that can be free of royalties, paid-software development kits, publishers or licenses.[48][49]

Games

Main article: List of Xbox 360 games
See also: List of Xbox games compatible with Xbox 360 and List of Xbox Originals

Halo 3
Halo 3

At the 2008 Game Developer Conference, Microsoft announced there would be over 1000 games available for Xbox 360 by the end of the year.[50] The 2007 Game Critics Awards honoured the Xbox 360 platform with 38 Nominations and 11 Wins - more than any other platform.[51] By March 2008, the Xbox 360 had reached a software attach rate of 7.5 games per console -- a record for any console in history, in EU the rate was 7.0 while its competitors were 3.8 (PS3) and 3.5 (Wii).[52]

The Xbox 360 launched with 14 games in North America and 13 in Europe. The console's best-selling game for 2005, Call of Duty 2, sold over a million copies.[53] Five other games sold as well in the console's first year in the market: Ghost Recon Advanced Warfighter,[54] The Elder Scrolls IV: Oblivion,[55] Dead or Alive 4,[56] Saints Row[57] and Gears of War.[58] Gears of War would become the best-selling game of the console with 3 million units,[59] before being surpassed in 2007 by Halo 3, with 8.1 million units.[3]

Six games were initially offered in Japan, and eagerly anticipated titles such as Dead or Alive 4 and Enchanted Arms were released only a few weeks later.[60] Games more suitable to the region were planned or have since been released, such as Chromehounds, Ninety-Nine Nights, and Phantasy Star Universe.[61] Microsoft also had the support of RPG developer Mistwalker, founded by Final Fantasy creator Hironobu Sakaguchi. Mistwalker's first game, Blue Dragon, was released in 2006 and had a limited-edition bundle which sold out quickly with over 10,000 pre-orders.[62] Blue Dragon became the best-selling Xbox 360 game in the region, with over 200,000 units. Mistwalker's second game, Lost Odyssey also sold over 100,000 copies.[63]

The Xbox 360 has managed to gain a simultaneous release of titles which were initially planned to be PS3 exclusive, including Devil May Cry,[64] Ace Combat,[65] Virtua Fighter,[66] and Final Fantasy XIII.[67], or PS3 timed exclusives, such as Grand Theft Auto 4.[68]

At E3 2007, Microsoft announced that Disney movies would be coming to Xbox 360 Live Marketplace. Gears of War was announced to be coming to the PC. New trailers were shown for Halo 3 and Halo Wars. A Halo-themed Xbox 360 was also announced. Details on Civilization Revolution and Fallout 3 were given. BioShock, Call of Duty 4: Modern Warfare, and Assassin's Creed for Xbox 360, as well as Crysis for the PC were demoed. At E3 2008, Microsoft announced a number of titles for their 2009 line-up, including Fallout 3, Gears of War 2, Fable II, and Resident Evil 5,Saint's Row 2, among other games. A television-style gaming feature known as Primetime was shown with a game based on the game show 1 vs. 100 shown as an example, there were also hints at a Big Brother type game and also a Deal or no Deal one. Final Fantasy XIII was also announced to be released for Xbox 360 in Europe and North America.

Xbox Live

Main article: Xbox Live

Official logo of Xbox Live
Official logo of Xbox Live
Xbox Live Dashboard
Xbox Live Dashboard

On the day of the Xbox 360's release, Microsoft's online gaming service Xbox Live was shut down for 24 hours and went through a major upgrade, adding a basic non-subscription service, Silver, to its already established premium subscription-based service (which was renamed Gold). Xbox Live Silver is free of charge and is included with all SKUs of the console. It allows users to create a user profile, join on message boards, and access Microsoft's Xbox Live Arcade and Marketplace and talk to other members.[69] A Live Silver account does not generally support multiplayer gaming; however, some games that have rather limited online functions already, (such as Viva Pinata) or games that feature their own subscription service (eg. EA Sports games) can be played with a Silver account. Xbox Live also supports voice and video communication, the latter a feature possible with the Xbox Live Vision; an add-on USB web camera designed specifically for the Xbox 360.[70] The Gamercard of a player with a Silver account has a silver trim, rather than gold.

Xbox Live Gold has the same features as Silver and includes integrated online game playing capabilities outside of third-party subscriptions. Microsoft has allowed previous Xbox Live subscribers to maintain their profile information, friends list, and games history when they make the transition to Xbox Live Gold. To transfer an Xbox Live account to the new system, users need to link a Windows Live ID to their gamertag on Xbox.com.[71] When users add an Xbox Live enabled profile to their console, they are required to provide the console with their passport account information and the last four digits of their credit card number, which is used for verification purposes and billing. An Xbox Live Gold account has an annual cost of US$49.99, C$59.99, NZD 90.00, GB£39.99, or €59.99. As of May 14, 2008, Xbox Live has over 12 million subscribers.[72]

Xbox Live Marketplace

Main article: Xbox Live Marketplace

Xbox Live Marketplace
Xbox Live Marketplace

The Xbox Live Marketplace is a virtual market designed for the console that allows Xbox Live users to download purchased or promotional content. The service offers movie and game trailers, game demos, Xbox Live Arcade games, gamertag images, and Xbox 360 Dashboard themes as well as add-on game content (items, costumes, levels etc). These features are available to both silver and gold members on Xbox Live. A hard drive or memory unit is required to store products purchased from Xbox Live Marketplace.[73] In order to download priced content, users are required to purchase Microsoft Points for use as scrip;[74] though some products (such as trailers) are free to download. Users are able to view items available to download on the service through a PC via the Xbox Live Pipeline website.[75] An estimated seventy percent of Xbox Live users have downloaded items from the Marketplace.[76]

Video Store
Xbox Video Marketplace
Xbox Video Marketplace

On November 6, 2006, Microsoft announced the Xbox Video Marketplace, an exclusive video store accessible through the console. Launched in the United States on November 22, 2006, the first anniversary of the Xbox 360's launch, the service allows users in the United States to download high-definition and standard-definition television shows and movies onto an Xbox 360 console for viewing. With the exception of short clips, content is not currently available for streaming, and must be downloaded. Microsoft has also announced that its Microsoft TV service will add IPTV functionality to the console, giving users the ability to stream 2 simultaneous HD and 2 simultaneous SD channels.[77] Movies are also available for rental. They expire in 14 days after download or at the end of the first 24 hours after the movie has begun playing, whichever comes first. Television episodes can be purchased to own, and are transferable to an unlimited number of consoles. Downloaded files use 5.1 surround audio and are encoded using VC-1 for video at 720p, with a bitrate of 6.8 Mbit/s.[78] Television content is offered from MTV, VH1, Comedy Central, Turner Broadcasting, and CBS; and movie content is Warner Bros., Paramount, and Disney, along with other publishers.[79]

After the Spring 2007 update, the following video codecs are supported:

* H.264 video support: Up to 15 Mbit/s, Baseline, Main, and High (up to level 4.1) Profiles with 2 channel AAC LC and Main Profiles.
* MPEG-4 Part 2 video support: Up to 8 Mbit/s, Simple Profile with 2 channel AAC LC and Main Profiles.

As a late addition to the December Xbox 360 update, 25 movies were added to the European Xbox 360 video market place on the December 11, 2007 and cost 250 Microsoft points for the SD version on the movie and 380 Microsoft points for the HD version of the movie.[80] Xbox Live members in Canada featured the ability to go on the Xbox Live Marketplace as of December 10, 2007 with around 30 movies to be downloaded for the same amount of Microsoft Points.

Xbox Live Arcade

Main article: Xbox Live Arcade

Xbox Live Arcade
Xbox Live Arcade

Xbox Live Arcade is an online service operated by Microsoft that is used to distribute downloadable video games to Xbox and Xbox 360 owners. In addition to classic arcade games such as Ms. Pac-Man, the service offers some new original games like Assault Heroes. The Xbox Live Arcade also features games from other consoles, such as the PlayStation game Castlevania: Symphony of the Night and PC games such as Zuma. The service was first launched on November 3, 2004,[81] using a DVD to load, and offered games for about US$5 to $15. Items are purchased using Microsoft Points, a proprietary currency used to reduce credit card transaction charges. On November 22, 2005, Xbox Live Arcade was re-launched with the release of the Xbox 360, in which it was now integrated with the Xbox 360's dashboard. The games are generally aimed toward more casual gamers; examples of the more popular titles are Geometry Wars: Retro Evolved, Street Fighter II' Hyper Fighting, and UNO.[82]

Home cinema, also called home theater, are entertainment systems that seek to reproduce cinema quality video and audio in a private home. In the 1950s, home movies became popular in the United States with Kodak 8 mm film projector equipment becoming affordable. The development of multi-channel audio systems and laserdisc in the 1980s created a new paradigm for home cinema. In the early to mid 1990's, a typical home cinema would have a Laserdisc or S-VHS videocassette player fed to a large rear projection television. In the late 1990s, home theatre technology progressed with the development of DVD, Dolby Digital 5.1-channel audio ("surround sound"), and High-Definition Television.

In the 2000s, the term "home cinema" encompasses a range of systems. The most basic system could be a DVD player, a standard CRT television, and a "home theater in a box", a 2.1 speaker system with left and right speakers and a small 8" subwoofer cabinet. An expensive home cinema set-up might include a High-Definition video format such as Blu-ray, a 60" High-Definition Television with a "cinema-style" 16×9 format, a several thousand-watt home theatre receiver with five to seven surround sound speakers, and a powered subwoofer with a 12" subwoofer. The most expensive home theater set-ups, which can cost over $100,000 US, have digital projectors, expensive screens, and custom-built screening rooms which include cinema-style chairs and Audiophile-grade sound equipment.



Component systems vs. Theater-in-a-Box

High-quality home cinemas are assembled from component pieces purchased separately to provide the best combination of equipment for the cost. It is possible to purchase home theater in a box kits that include a set of speakers for surround sound, an amplifier/tuner for adjusting volume and selecting video sources, and sometimes a DVD player. Though these kits often pale in comparison to a custom-built home cinema, they are inexpensive and easy to set up; one needs only to add a television and some movies in order to create a simple home theater. This makes them popular in the public's eyes.

Dedicated home theaters
A home theater with video projector mounted in a box on the ceiling.
A home theater with video projector mounted in a box on the ceiling.
Built-in shelves provide a place for movie decor, DVDs, and equipment. Note the component stack on the right, where the audio receiver, DVD player, secondary monitor, and video game system are located.
Built-in shelves provide a place for movie decor, DVDs, and equipment. Note the component stack on the right, where the audio receiver, DVD player, secondary monitor, and video game system are located.
The same projection screen as at top, without image.
The same projection screen as at top, without image.

Some home cinema enthusiasts go so far as to build a dedicated room in the home for the theater. These more advanced installations often include sophisticated acoustic design elements, including "room-in-a-room" construction that isolates sound and provides the potential for a nearly ideal listening environment. These installations are often designated as "screening rooms" to differentiate from simpler installations.

This idea can go as far as completely recreating an actual cinema, with a projector enclosed in a projection booth, specialized furniture, a piano or theatre organ, curtains in front of the projection screen, movie posters, or a popcorn or snack machine. More commonly, real dedicated home theaters pursue this to a lesser degree. Presently the days of the $100,000 and over home theater is being usurped by the rapid advances in digital audio and video technologies, which has spurred a rapid drop in prices. This in turn has brought the true digital home theater experience to the doorsteps of the do-it-yourself people, often for less than what you would expect to pay for a low budget economy car. Current consumer level A/V equipment can meet and often exceed in performance what you would expect to experience at a modern commercial theater.

Home Theater Seating

Home theater seating consists of chairs specifically engineered and designed for viewing movies in a personal home theater setting. Most home theater seats have cup holder built into the chairs' armrests and a shared armrest between each seat. Some seating is movie theater-style chairs like those seen in a movie cinema, which features a flip up seat cushion. Other seating systems have plush leather reclining lounger types, with flip-out footrests. Additional features like storage compartments, snack trays, tactile transducers (nicknamed "Bass Shakers"), or even electric motors to recline the chair are available, depending on the model.

Backyard theater

In places that have the proper outdoor atmosphere, it is possible for people to set up a home theater in their backyard. Depending on the space available, it may simply be a temporary version with foldable screen, a projector and couple of speakers, or a permanent fixture with huge screens and dedicated audio set up poolside. Due to the outdoor nature, it is quite popular with BBQ parties and pool parties.

Some specialist outdoor home cinema companies are now marketing packages with inflatable movie screens and purpose built AV systems.[1]

Some people have built upon the idea, and constructed mobile drive-in theaters that can play movies in public open spaces. Usually, these require a powerful projector, a laptop or DVD player, outdoor speakers and/or an FM transmitter to broadcast the audio to other car radios.[2][3]

History

1960s

In the 1950s, home movies became popular in the United States and elsewhere as Kodak 8 mm film (Pathé 9.5 mm in France) and camera and projector equipment became affordable. Projected with a small, portable movie projector onto a portable screen, often without sound, this system became the first practical home theater. They were generally used to show home movies of family travels and celebrations but also doubled as a means of showing private stag films. Dedicated home cinemas were called screening rooms at the time and were outfitted with 16 mm or even 35 mm projectors for showing commercial films. These were found almost exclusively in the homes of the very wealthy, especially those in the movie industry.

Portable home cinemas improved over time with color film, Kodak Super 8 mm film film cartridges, and monaural sound but remained awkward and somewhat expensive. The rise of home video in the late 1970s almost completely killed the consumer market for 8 mm film cameras and projectors, as VCRs connected to ordinary televisions provided a simpler and more flexible substitute.

1980s

The development of multi-channel audio systems and laserdisc in the 1980s added new dimensions for home cinema. The first known home cinema system was installed as a sales tool at Kirshmans furniture store in Metairie, Louisiana in 1974. They built a special sound room which incorporated the earliest quadraphonic audio systems and modified Sony trinitron televisions for projecting the image. Many systems were sold in the New Orleans area in the ensuing years before the first public demonstration of this integration occurred in 1982 at the Summer Consumer Electronics Show in Chicago, Illinois. Peter Tribeman of NAD (USA) organized and presented a demonstration made possible by the collaborative effort of NAD, Proton, ADS, Lucasfilm and Dolby Labs who contributed their technologies to demonstrate what a home cinema would "look and sound" like.

Over the course of three days, retailers, manufacturers, and members of the consumer electronics press were exposed to the first "home like" experience of combining a high quality video source with multi-channel surround sound. That one demonstration is credited with being the impetus for developing what is now a multi-billion dollar business.

1990s and 2000s

In the early to mid 90's, a typical Home Cinema would have a Laserdisc or S-VHS player fed to a large screen: rear projection for the more affordable setups, and LCD or CRT front projection in the more elaborate. In the late 1990s, the development of DVD, 5.1-channel audio, and high-quality video projectors that provide a cinema experience at a price that rivals a big-screen HDTVs sparked a new wave of home cinema interest. In the 2000s, developments such as High Definition video and newer HD display technologies enable people to enjoy a cinematic feeling in their own home at an affordable price.

A liquid crystal display (LCD) is an electro-optical amplitude modulator realized as a thin, flat display device made up of any number of color or monochrome pixels arrayed in front of a light source or reflector. It is often utilized in battery-powered electronic devices because it uses very small amounts of electric power.

A comprehensive classification of the various types and electro-optical modes of LCDs is provided here.


Each pixel of an LCD typically consists of a layer of molecules aligned between two transparent electrodes, and two polarizing filters, the axes of transmission of which are (in most of the cases) perpendicular to each other. With no liquid crystal between the polarizing filters, light passing through the first filter would be blocked by the second (crossed) polarizer.

The surface of the electrodes that are in contact with the liquid crystal material are treated so as to align the liquid crystal molecules in a particular direction. This treatment typically consists of a thin polymer layer that is unidirectionally rubbed using, for example, a cloth. The direction of the liquid crystal alignment is then defined by the direction of rubbing. Electrodes are made of a transparent conductor called Indium Tin Oxide (ITO).

Before applying an electric field, the orientation of the liquid crystal molecules is determined by the alignment at the surfaces. In a twisted nematic device (still the most common liquid crystal device), the surface alignment directions at the two electrodes are perpendicular to each other, and so the molecules arrange themselves in a helical structure, or twist. Because the liquid crystal material is birefringent, light passing through one polarizing filter is rotated by the liquid crystal helix as it passes through the liquid crystal layer, allowing it to pass through the second polarized filter. Half of the incident light is absorbed by the first polarizing filter, but otherwise the entire assembly is reasonably transparent.
LCD with top polarizer removed from device and placed on top, such that the top and bottom polarizers are crossed.
LCD with top polarizer removed from device and placed on top, such that the top and bottom polarizers are crossed.

When a voltage is applied across the electrodes, a torque acts to align the liquid crystal molecules parallel to the electric field, distorting the helical structure (this is resisted by elastic forces since the molecules are constrained at the surfaces). This reduces the rotation of the polarization of the incident light, and the device appears grey. If the applied voltage is large enough, the liquid crystal molecules in the center of the layer are almost completely untwisted and the polarization of the incident light is not rotated as it passes through the liquid crystal layer. This light will then be mainly polarized perpendicular to the second filter, and thus be blocked and the pixel will appear black. By controlling the voltage applied across the liquid crystal layer in each pixel, light can be allowed to pass through in varying amounts thus constituting different levels of gray.
LCD with top polarizer removed from device and placed on top, such that the top and bottom polarizers are parallel.
LCD with top polarizer removed from device and placed on top, such that the top and bottom polarizers are parallel.

The optical effect of a twisted nematic device in the voltage-on state is far less dependent on variations in the device thickness than that in the voltage-off state. Because of this, these devices are usually operated between crossed polarizers such that they appear bright with no voltage (the eye is much more sensitive to variations in the dark state than the bright state). These devices can also be operated between parallel polarizers, in which case the bright and dark states are reversed. The voltage-off dark state in this configuration appears blotchy, however, because of small variations of thickness across the device.

Both the liquid crystal material and the alignment layer material contain ionic compounds. If an electric field of one particular polarity is applied for a long period of time, this ionic material is attracted to the surfaces and degrades the device performance. This is avoided either by applying an alternating current or by reversing the polarity of the electric field as the device is addressed (the response of the liquid crystal layer is identical, regardless of the polarity of the applied field).

When a large number of pixels are needed in a display, it is not technically possible to drive each directly since then each pixel would require independent electrodes. Instead, the display is multiplexed. In a multiplexed display, electrodes on one side of the display are grouped and wired together (typically in columns), and each group gets its own voltage source. On the other side, the electrodes are also grouped (typically in rows), with each group getting a voltage sink. The groups are designed so each pixel has a unique, unshared combination of source and sink. The electronics, or the software driving the electronics then turns on sinks in sequence, and drives sources for the pixels of each sink.

[edit] Specifications

Important factors to consider when evaluating an LCD monitor:

* Resolution: The horizontal and vertical size expressed in pixels (e.g., 1024x768). Unlike monochrome CRT monitors, LCD monitors have a native-supported resolution for best display effect.
* Dot pitch: The distance between the centers of two adjacent pixels. The smaller the dot pitch size, the less granularity is present, resulting in a sharper image. Dot pitch may be the same both vertically and horizontally, or different (less common).
* Viewable size: The size of an LCD panel measured on the diagonal (more specifically known as active display area).
* Response time: The minimum time necessary to change a pixel's color or brightness. Response time is also divided into rise and fall time. For LCD Monitors, this is measured in btb (black to black) or gtg (gray to gray). These different types of measurements make comparison difficult.
* Refresh rate: The number of times per second in which the monitor draws the data it is being given. A refresh rate that is too low can cause flickering and will be more noticeable on larger monitors. Many high-end LCD televisions now have a 120 Hz refresh rate (current and former NTSC countries only)[citation needed]. This allows for less distortion when movies filmed at 24 frames per second (fps) are viewed due to the elimination of telecine (3:2 pulldown). The rate of 120 was chosen as the least common multiple of 24 fps (cinema) and 30 fps (TV).
* Matrix type: Active TFT or Passive.
* Viewing angle: (coll., more specifically known as viewing direction).
* Color support: How many types of colors are supported (coll., more specifically known as color gamut).
* Brightness: The amount of light emitted from the display (coll., more specifically known as luminance).
* Contrast ratio: The ratio of the intensity of the brightest bright to the darkest dark.
* Aspect ratio: The ratio of the width to the height (for example, 4:3, 16:9 or 16:10).
* Input ports (e.g., DVI, VGA, LVDS, DisplayPort, or even S-Video and HDMI).

Display that have built-in TV Tuner or decoders may feature

* Gamma correction

Brief history

* 1888: Friedrich Reinitzer (1858-1927) discovers the liquid crystalline nature of cholesterol extracted from carrots (that is, two melting points and generation of colors) and published his findings at a meeting of the Vienna Chemical Society on May 3, 1888 (F. Reinitzer: Beiträge zur Kenntniss des Cholesterins, Monatshefte für Chemie (Wien) 9, 421-441 (1888)).[1]

* 1904: Otto Lehmann publishes his work "Flüssige Krystalle" (Liquid Crystals).

* 1911: Charles Mauguin first experiments of liquids crystals confined between plates in thin layers.

* 1922: George Friedel describes the structure and properties of liquid crystals and classified them in 3 types (nematics, smectics and cholesterics).

* 1936: The Marconi Wireless Telegraph company patents the first practical application of the technology, "The Liquid Crystal Light Valve".

* 1962: The first major English language publication on the subject "Molecular Structure and Properties of Liquid Crystals", by Dr. George W. Gray.[2]

* 1962: Richard Williams of RCA found that liquid crystals had some interesting electro-optic characteristics and he realized an electro-optical effect by generating stripe-patterns in a thin layer of liquid crystal material by the application of a voltage. This effect is based on an electro-hydrodynamic instability forming what is now called “Williams domains” inside the liquid crystal.[3]

* 1964: In the fall of 1964 George H. Heilmeier, then working in the RCA laboratories on the effect discovered by Williams realized the switching of colors by field-induced realignment of dichroic dyes in a homeotropically oriented liquid crystal. Practical problems with this new electro-optical effect made Heilmeier to continue work on scattering effects in liquid crystals and finally the realization of the first operational liquid crystal display based on what he called the dynamic scattering mode (DSM). Application of a voltage to a DSM display switches the initially clear transparent liquid crystal layer into a milky turbid state. DSM displays could be operated in transmissive and in reflective mode but they required a considerable current to flow for their operation.[4][5][6]

* 1960s: Pioneering work on liquid crystals was undertaken in the late 1960s by the UK's Royal Radar Establishment at Malvern. The team at RRE supported ongoing work by George Gray and his team at the University of Hull who ultimately discovered the cyanobiphenyl liquid crystals (which had correct stability and temperature properties for application in LCDs).

* 1970: On December 4, 1970, the twisted nematic field effect in liquid crystals was filed for patent by Hoffmann-LaRoche in Switzerland, (Swiss patent No. 532 261) with Wolfgang Helfrich and Martin Schadt (then working for the Central Research Laboratories) listed as inventors.[4] Hoffmann-La Roche then licensed the invention to the Swiss manufacturer Brown, Boveri & Cie who produced displays for wrist watches during the 1970s and also to Japanese electronics industry which soon produced the first digital quartz wrist watches with TN-LCDs and numerous other products. James Fergason at the Westinghouse Research Laboratories in Pittsburgh while working with Sardari Arora and Alfred Saupe at Kent State University Liquid Crystal Institute filed an identical patent in the USA on April 22, 1971.[7] In 1971 the company of Fergason ILIXCO (now LXD Incorporated) produced the first LCDs based on the TN-effect, which soon superseded the poor-quality DSM types due to improvements of lower operating voltages and lower power consumption.
* 1972: The first active-matrix liquid crystal display panel was produced in the United States by T. Peter Brody.[8]
* 2007: In the 4Q of 2007 for the first time LCD surpassed CRT in worldwide sales.[9]
* 2008: LCD TVs are the main stream with 50% market share of the 200 million TVs forecast to ship globally in 2008 according to Display Bank.[10]

A detailed description of the origins and the complex history of liquid crystal displays from the perspective of an insider during the early days has been published by Joseph A. Castellano in "Liquid Gold, The Story of Liquid Crystal Displays and the Creation of an Industry" [11]. Another report on the origins and history of LCD from a different perspective has been published by Hiroshi Kawamoto, available at the IEEE History Center.[12]
Color displays
A subpixel of a color LCD
A subpixel of a color LCD
Simulation of an LCD monitor up close
Simulation of an LCD monitor up close
Comparison of the OLPC XO-1 display (left) with a typical color LCD. The images show 1×1 mm of each screen. A typical LCD addresses groups of 3 locations as pixels. The XO-1 display addresses each location as a separate pixel.
Comparison of the OLPC XO-1 display (left) with a typical color LCD. The images show 1×1 mm of each screen. A typical LCD addresses groups of 3 locations as pixels. The XO-1 display addresses each location as a separate pixel.

In color LCDs each individual pixel is divided into three cells, or subpixels, which are colored red, green, and blue, respectively, by additional filters (pigment filters, dye filters and metal oxide filters). Each subpixel can be controlled independently to yield thousands or millions of possible colors for each pixel. CRT monitors employ a similar 'subpixel' structures via phosphors, although the electron beam employed in CRTs do not hit exact 'subpixels'.

Color components may be arrayed in various pixel geometries, depending on the monitor's usage. If software knows which type of geometry is being used in a given LCD, this can be used to increase the apparent resolution of the monitor through subpixel rendering. This technique is especially useful for text anti-aliasing.

To reduce smudging in a moving picture when pixels do not respond quickly enough to color changes, so-called pixel overdrive may be used.

[edit] Passive-matrix and active-matrix addressed LCDs
A general purpose alphanumeric LCD, with two lines of 16 characters.
A general purpose alphanumeric LCD, with two lines of 16 characters.

LCDs with a small number of segments, such as those used in digital watches and pocket calculators, have individual electrical contacts for each segment. An external dedicated circuit supplies an electric charge to control each segment. This display structure is unwieldy for more than a few display elements.

Small monochrome displays such as those found in personal organizers, or older laptop screens have a passive-matrix structure employing super-twisted nematic (STN) or double-layer STN (DSTN) technology—the latter of which addresses a color-shifting problem with the former—and color-STN (CSTN)—wherein color is added by using an internal filter. Each row or column of the display has a single electrical circuit. The pixels are addressed one at a time by row and column addresses. This type of display is called passive-matrix addressed because the pixel must retain its state between refreshes without the benefit of a steady electrical charge. As the number of pixels (and, correspondingly, columns and rows) increases, this type of display becomes less feasible. Very slow response times and poor contrast are typical of passive-matrix addressed LCDs.

High-resolution color displays such as modern LCD computer monitors and televisions use an active matrix structure. A matrix of thin-film transistors (TFTs) is added to the polarizing and color filters. Each pixel has its own dedicated transistor, allowing each column line to access one pixel. When a row line is activated, all of the column lines are connected to a row of pixels and the correct voltage is driven onto all of the column lines. The row line is then deactivated and the next row line is activated. All of the row lines are activated in sequence during a refresh operation. Active-matrix addressed displays look "brighter" and "sharper" than passive-matrix addressed displays of the same size, and generally have quicker response times, producing much better images.

[edit] Active matrix technologies
A Casio 1.8" colour TFT liquid crystal display which equips the Sony Cyber-shot DSC-P93A digital compact cameras
A Casio 1.8" colour TFT liquid crystal display which equips the Sony Cyber-shot DSC-P93A digital compact cameras

Main article: TFT LCD, Active-matrix liquid crystal display

Twisted nematic (TN)

Twisted nematic displays contain liquid crystal elements which twist and untwist at varying degrees to allow light to pass through. When no voltage is applied to a TN liquid crystal cell, the light is polarized to pass through the cell. In proportion to the voltage applied, the LC cells twist up to 90 degrees changing the polarization and blocking the light's path. By properly adjusting the level of the voltage almost any grey level or transmission can be achieved.

For a more comprehensive description refer to the section on the twisted nematic field effect.

In-plane switching (IPS)

In-plane switching is an LCD technology which aligns the liquid crystal cells in a horizontal direction. In this method, the electrical field is applied through each end of the crystal, but this requires two transistors for each pixel instead of the single transistor needed for a standard thin-film transistor (TFT) display. This results in blocking more transmission area, thus requiring a brighter backlight, which will consume more power, making this type of display less desirable for notebook computers.

[edit] Vertical alignment (VA)

Vertical alignment displays are a form of LC displays in which the liquid crystal material naturally exists in a horizontal state removing the need for extra transistors (as in IPS). When no voltage is applied the liquid crystal cell, it remains perpendicular to the substrate creating a black display. When voltage is applied, the liquid crystal cells shift to a horizontal position, parallel to the substrate, allowing light to pass through and create a white display. VA liquid crystal displays provide some of the same advantages as IPS panels, particularly an improved viewing angle and improved black level.

Blue Phase mode

Main article: Blue Phase Mode LCD

In blue phase based LC-displays for TV applications it is not the selective reflection of light according the lattice pitch (Bragg reflection), but an electric field deforms the lattice which results in anisotropy of the refractive indices of the layer, followed by a change of transmission between crossed polarizers.

Developed with a look at cost-efficiency, blue phase mode LCDs do not require liquid crystal alignment layers, unlike today’s most widely used LCD modes such as Twisted Nematic (TN), In-Plane Switching (IPS) or Vertical Alignment (VA) modes. The blue phase mode can make its own alignment layers, eliminating the need for any mechanical alignment and rubbing processes. This reduces the number of required fabrication steps, resulting in savings on production costs. Additionally it has been claimed that blue phase panels will reduce sensitivity of the LC-layer to mechanical pressure which can impair the lateral uniformity of display luminance.[citation needed]

Overdrive circuits that are currently applied to many LCD panels with 120 Hz frame frequency for improvement of the display of moving images in premium LCD TVs will become obsolete since the blue phase mode features a superior response speed, allowing images to be reproduced at 240 Hz frame rate or higher without the need for any overdrive circuit [13].

Quality control

Some LCD panels have defective transistors, causing permanently lit or unlit pixels which are commonly referred to as stuck pixels or dead pixels respectively. Unlike integrated circuits (ICs), LCD panels with a few defective pixels are usually still usable. It is also economically prohibitive to discard a panel with just a few defective pixels because LCD panels are much larger than ICs. Manufacturers have different standards for determining a maximum acceptable number of defective pixels. The maximum acceptable number of defective pixels for LCD varies greatly. At one point, Samsung held a zero-tolerance policy for LCD monitors sold in Korea.[14] Currently, though, Samsung adheres to the less restrictive ISO 13406-2 standard.[15] Other companies have been known to tolerate as many as 11 dead pixels in their policies.[16] Dead pixel policies are often hotly debated between manufacturers and customers. To regulate the acceptability of defects and to protect the end user, ISO released the ISO 13406-2 standard.[17] However, not every LCD manufacturer conforms to the ISO standard and the ISO standard is quite often interpreted in different ways.
Examples of defects in LCDs
Examples of defects in LCDs

LCD panels are more likely to have defects than most ICs due to their larger size. In the example to the right, a 300 mm SVGA LCD has 8 defects and a 150 mm wafer has only 3 defects. However, 134 of the 137 dies on the wafer will be acceptable, whereas rejection of the LCD panel would be a 0% yield. The standard is much higher now due to fierce competition between manufacturers and improved quality control. An SVGA LCD panel with 4 defective pixels is usually considered defective and customers can request an exchange for a new one. Some manufacturers, notably in South Korea where some of the largest LCD panel manufacturers, such as LG, are located, now have "zero defective pixel guarantee", which is an extra screening process which can then determine "A" and "B" grade panels. Many manufacturers would replace a product even with one defective pixel. Even where such guarantees do not exist, the location of defective pixels is important. A display with only a few defective pixels may be unacceptable if the defective pixels are near each other. Manufacturers may also relax their replacement criteria when defective pixels are in the center of the viewing area.

LCD panels also have defects known as mura, which look like a small-scale crack with very small changes in luminance or color.[18] It is most visible in dark or black areas of displayed scenes. Defects in various LCD panel components can cause mura effect.[clarify]

Zero-power (bistable) displays

The zenithal bistable device (ZBD), developed by QinetiQ (formerly DERA), can retain an image without power. The crystals may exist in one of two stable orientations (Black and "White") and power is only required to change the image. ZBD Displays is a spin-off company from QinetiQ who manufacture both grayscale and color ZBD devices.

A French company, Nemoptic, has developed another zero-power, paper-like LCD technology which has been mass-produced since July 2003. This technology is intended for use in applications such as Electronic Shelf Labels, E-books, E-documents, E-newspapers, E-dictionaries, Industrial sensors, Ultra-Mobile PCs, etc. Zero-power LCDs are a category of electronic paper.

Kent Displays has also developed a "no power" display that uses Polymer Stabilized Cholesteric Liquid Crystals (ChLCD). The major drawback to the ChLCD is slow refresh rate, especially with low temperatures.

In 2004 researchers at the University of Oxford demonstrated two new types of zero-power bistable LCDs based on Zenithal bistable techniques.[19]

Several bistable technologies, like the 360° BTN and the bistable cholesteric, depend mainly on the bulk properties of the liquid crystal (LC) and use standard strong anchoring, with alignment films and LC mixtures similar to the traditional monostable materials. Other bistable technologies (i.e. Binem Technology) are based mainly on the surface properties and need specific weak anchoring materials

Standard keyboards

Standard keyboards such as 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).[1]

Keyboards with extra keys such as multimedia keyboards have special keys for accessing music, web, and other oft-used programs, a mute button, volume buttons or knob, and standby (sleep) button. gaming keyboards have extra function keys which can be programmed with keystroke macros. For example, ctrl+shift+y could be a keystroke that is frequently used in a certain computer game. Shortcuts marked on color-coded keys are used for some software applications and for specialized for uses including word processing, video editing, graphic design, and audio editing.
Multimedia keyboards have special keys for accessing music, websites, and computer programs.
Multimedia keyboards have special keys for accessing music, websites, and computer programs.

Smaller keyboards have been introduced for laptops, PDAs, cellphones, or users who have a limited workspace. The size of a standard keyboard is dictated by the practical consideration that the keys must be large enough to be easily pressed by fingers. To reduce the size of the keyboard, the numeric keyboard to the right of the alphabetic keyboard can be removed, or the size of the keys can be reduced, which makes it harder to enter text. Another way to reduce the size of the keyboard is to reduce the number of keys and use chording keyer, i.e. 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. Another way to reduce the size of a keyboard is to use smaller buttons and pack them closer together. Such keyboards, often called a "thumbboard" (thumbing) are used in some personal digital assistants such as the Treo and BlackBerry and some Ultra-Mobile PCs such as the OQO.
Keyboards on laptops such as this Sony VAIO usually have a shorter travel distance for the keystroke and a reduced set of keys.
Keyboards on laptops such as this Sony VAIO usually have a shorter travel distance for the keystroke and a reduced set of keys.

Numeric keyboards contain only numbers, mathematical symbols for addition, subtraction, multiplication, and division, a decimal point, and several function keys (e.g. End, Delete, etc.). They are often used to facilitate data entry with smaller keyboard-equipped laptops or with smaller keyboards that do not have a numeric keypad.

Non-standard or special-use types

A keyset or chorded keyboard (also called a chord keyboard or chording keyboard) is a computer input device that allows the user to enter characters or commands formed by pressing several keys together, like playing a "chord" on a piano. The large number of combinations available from a small number of keys allows text or commands to be entered with one hand, leaving the other hand free to do something else. A secondary advantage is that it can be built into a device (such as a pocket-sized computer) that is too small to contain a normal sized keyboard. A chorded keyboard designed to be used while held in the hand is called a keyer.
The Microwriter MW4 (circa 1980) uses a chording keyboard in which several key presses are needed for each letter.
The Microwriter MW4 (circa 1980) uses a chording keyboard in which several key presses are needed for each letter.

Virtual keyboards, such as the I-Tech Virtual Laser Keyboard, project an image of a full-size keyboard onto a surface. Sensors in the projection unit identify which key is being "pressed" and relay the signals to a computer or personal digital assistant. There is also a virtual keyboard, the On-Screen Keyboard, for use on WIndows.

Touchscreens such as with the iPhone and the OLPC laptop can be used as a keyboard. (The OLPC initiative's second computer will be effectively two tablet touchscreens hinged together like a book. It can be used as a convertible tablet PC where the keyboard is one half-screen (one side of the book) which turns into a touchscreen virtual keyboard.)
A foldable keyboard.
A foldable keyboard.

Foldable keyboards are made of soft plastic which can be rolled or folded over for travel. When in use, the keyboard can conform to uneven surfaces, and it is more resistant to liquids than a standard keyboard.

Layout

Main article: Keyboard layout

Alphabetic layout

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. 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 reduced 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 Dvorak Simplified Keyboard layout arranges keys so that frequently used keys are easiest to press, which reduces muscle fatigue when typing common English.
The Dvorak Simplified Keyboard layout arranges keys so that frequently used keys are easiest to press, which reduces muscle fatigue when typing common English.

The QWERTZ layout is fairly 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.
A Hebrew keyboard lets the user type in both Hebrew and the Latin alphabet.
A Hebrew keyboard lets the user type in both Hebrew and the Latin alphabet.

Keyboards designed for non-English speaking markets may have special keys to switch between non-English typing and the Roman alphabet and vice-versa. In Japan, keyboards often can be switched between Japanese and the Roman alphabet, and the character ¥ (the Yen currency) is used instead of "\". In Israel, keyboards can often be switched between Hebrew and English. In bilingual regions of Canada and in the French-speaking province of Quebec, 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 keys

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.

Special keys

Modifier keys are special keys on a computer keyboard that modify the normal action of another key when the two are pressed in combination. For example, + in Microsoft Windows will close the program in an active window. In contrast, pressing just will probably do nothing unless assigned a specific function in a particular program. By themselves, modifier keys usually do nothing. 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 diacritic mark such as an accent) on the following letter (e.g., the Compose key).

The Return key / Enter 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 mode keys

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 Page up key and the Page down key, 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 command keys

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 typically captures the entire screen and sends it to the printer. The Break/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 mean Stop. 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 XP and Windows Vista.

The Menu key or Application key is a key found on Windows-oriented computer keyboards. It is used 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 keys

Many, but not all computer keyboards have a numeric keypad to the right of the alphabetic keyboard. 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.

Technology

Key switches

"Dome-switch" keyboards (sometimes incorrectly referred to as a membrane keyboards) are the most common type in use in the 2000s. When a key is pressed, it pushes down on a rubber dome sitting beneath the key. A conductive contact on the underside of the dome touches (and hence connects) a pair of conductive lines on the circuit below. This bridges the gap between them and allows electric current to flow (the open circuit is closed). A scanning signal is emitted by the chip along the pairs of lines in the matrix circuit which connects to all the keys. When the signal in one pair becomes different, the chip generates a "make code" corresponding to the key connected to that pair of lines. Keycaps are also required for most types of keyboards; while modern keycaps are typically surface-marked, they can also be 2-shot molded, or engraved, or they can be made of transparent material with printed paper inserts

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.[2][3]When a key is pressed and the circuit is completed, the code generated is sent to the computer either via a keyboard cable (using on-off electrical pulses to represent bits) or over a wireless connection.

A chip inside the computer receives the signal bits and decodes them into the appropriate keypress. The computer then decides what to do on the basis of the key pressed (e.g. display a character on the screen, or perform some action). When the key is released, a break code (different than the make code) is sent to indicate the key is no longer pressed. If the break code is missed (e.g. due to a keyboard switch) it is possible for the keyboard controller to believe the key is pressed down when it is not, which is why pressing then releasing the key again will release the key (since another break code is sent). Other types of keyboards function in a similar manner, the main differences being how the individual key-switches work. For more on this subject refer to the article on keyboard technology.

Certain key presses are special, namely Ctrl-Alt-Delete and SysRq, but what makes them special is a function of software. In the PC architecture, the keyboard controller (the component in the computer that receives the make and break codes) sends the computer's CPU a hardware interrupt whenever a key is pressed or released. The CPU's interrupt routine which handles these interrupts usually just places the key's code in a queue, to be handled later by other code when it gets around to it, then returns to whatever the computer was doing before. The special keys cause the interrupt routine to take a different "emergency" exit instead. This more trusted route is much harder to intercept.

The layout of a keyboard can be changed by remapping the keys. When you remap a key, you tell the computer a new meaning for the pressing of that key. Keyboard remapping is supported at a driver-level configurable within the operating system, or as add-ons to the existing programs. For Windows, Microsoft provides a downloadable tool called Microsoft Keyboard Layout Creator, and there are several other software programs, including SharpKeys and KeyTweak.

Control processor

The modern PC keyboard has more than switches. It also includes a control processor and indicator lights to provide feedback to the user about what state the keyboard is in. Depending on the sophistication of the controller's programming, the keyboard may also offer other special features. The processor is usually a single chip 8048 microcontroller variant. The keyboard switch matrix is wired to its inputs and it processes the incoming keystrokes and sends the results down a serial cable (the keyboard cord) to a receiver in the main computer box. It also controls the illumination of the "caps lock", "num lock" and "scroll lock" lights.

A common 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.

When pressing a keyboard key, the key "bounces" like a ball against its contacts several times before it settles into firm contact. When released, it bounces some more until it reverts to the uncontacted state. If the computer was 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 suffer problems with rollover (that is, when multiple keys are pressed in quick succession); some types of keyboard circuitry will register a maximum number of keys at one time. This is undesirable for games (designed for multiple keypresses, e.g. casting a spell while holding down keys to run) and undesirable for extremely fast typing (hitting new keys before the fingers can release previous keys). A common side effect of this shortcoming is called "phantom key blocking": on some keyboards, pressing three keys simultaneously sometimes resulted in a 4th keypress being registered. Modern keyboards prevent this from happening by blocking the 3rd key in certain key combinations, but while this prevents phantom input, it also means that when two keys are depressed simultaneously, many of the other keys on the keyboard will not respond until one of the two depressed keys is lifted. With better keyboards designs, this seldom happens in office programs, but it remains a problem in games even on expensive keyboards, due to wildly different and/or configurable key/command layouts in different games.

Connection types

There are several ways of connecting a keyboard 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.[4]

Alternative text-entering methods
An on-screen keyboard controlled with the mouse can be used by users with limited mobility.
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. FITALY (http://www.FITALY.com) is a stylus/one-finger keyboard that can yield 50+ WPM. The key is to stare at the keyboard, not the screen (as in traditional touch typing). No memorization of layout is required. It is engineered for rapid text input (e.g., some 85% of English words are visible at the center of the keyboard). It is available for many mobile and laptop devices.

Other issues

Keystroke hacking

Keystroke logging (often called keylogging) is a method of capturing and recording user keystrokes. While it is used legitimately 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 law-breaking. Hackers use keyloggers as a means to obtain passwords or encryption keys and thus bypassing 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 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[5].

Physical injury

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.
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.
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.[6]

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 keyboard layout such as Dvorak[citation needed] or Colemak may reduce the risk of injury. 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 such as a Smart Cat trackpad can lessen the repetitive strain on the arms and hands.