1.
Linux
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Linux is a Unix-like computer operating system assembled under the model of free and open-source software development and distribution. The defining component of Linux is the Linux kernel, an operating system kernel first released on September 17,1991 by Linus Torvalds, the Free Software Foundation uses the name GNU/Linux to describe the operating system, which has led to some controversy. Linux was originally developed for computers based on the Intel x86 architecture. Because of the dominance of Android on smartphones, Linux has the largest installed base of all operating systems. Linux is also the operating system on servers and other big iron systems such as mainframe computers. It is used by around 2. 3% of desktop computers, the Chromebook, which runs on Chrome OS, dominates the US K–12 education market and represents nearly 20% of the sub-$300 notebook sales in the US. Linux also runs on embedded systems – devices whose operating system is built into the firmware and is highly tailored to the system. This includes TiVo and similar DVR devices, network routers, facility automation controls, televisions, many smartphones and tablet computers run Android and other Linux derivatives. The development of Linux is one of the most prominent examples of free, the underlying source code may be used, modified and distributed—commercially or non-commercially—by anyone under the terms of its respective licenses, such as the GNU General Public License. Typically, Linux is packaged in a known as a Linux distribution for both desktop and server use. Distributions intended to run on servers may omit all graphical environments from the standard install, because Linux is freely redistributable, anyone may create a distribution for any intended use. The Unix operating system was conceived and implemented in 1969 at AT&Ts Bell Laboratories in the United States by Ken Thompson, Dennis Ritchie, Douglas McIlroy, first released in 1971, Unix was written entirely in assembly language, as was common practice at the time. Later, in a key pioneering approach in 1973, it was rewritten in the C programming language by Dennis Ritchie, the availability of a high-level language implementation of Unix made its porting to different computer platforms easier. Due to an earlier antitrust case forbidding it from entering the computer business, as a result, Unix grew quickly and became widely adopted by academic institutions and businesses. In 1984, AT&T divested itself of Bell Labs, freed of the legal obligation requiring free licensing, the GNU Project, started in 1983 by Richard Stallman, has the goal of creating a complete Unix-compatible software system composed entirely of free software. Later, in 1985, Stallman started the Free Software Foundation, by the early 1990s, many of the programs required in an operating system were completed, although low-level elements such as device drivers, daemons, and the kernel were stalled and incomplete. Linus Torvalds has stated that if the GNU kernel had been available at the time, although not released until 1992 due to legal complications, development of 386BSD, from which NetBSD, OpenBSD and FreeBSD descended, predated that of Linux. Torvalds has also stated that if 386BSD had been available at the time, although the complete source code of MINIX was freely available, the licensing terms prevented it from being free software until the licensing changed in April 2000
2.
Tablet computer
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Tablets often come equipped with sensors, including digital cameras, a microphone, and an accelerometer so images on screens are always displayed upright. The touchscreen display uses the recognition of finger or stylus gestures to replace the mouse, trackpad, tablets are typically larger than smartphones or personal digital assistants with screens 7 inches or larger, measured diagonally. However much of a tablets functionality resembles that of a modern smartphone, tablets can be classified according to the presence and physical appearance of keyboards. Slates and booklets do not have a keyboard, and usually accept text. Hybrids, convertibles, and 2-in-1s do have physical keyboards, yet they also make use of virtual keyboards. Some 2-in-1s have processors and operating systems like a full laptop, most tablets can use separate keyboards connected using Bluetooth. The format was conceptualized in the century and prototyped and developed in the last two decades of that century. In April 2010, Apple released the iPad, the first mass-market tablet to achieve widespread popularity, thereafter in the 2010s, tablets rapidly rose in ubiquity and became a large product category used for both personal and workplace applications. The tablet computer and its operating system began with the development of pen computing. Throughout the 20th century devices with these characteristics have been imagined and created whether as blueprints, prototypes, a device more powerful than todays tablets appeared briefly in Jerry Pournelle and Larry Nivens The Mote in Gods Eye. Adults could also use a Dynabook, but the audience was children. In 1992, Atari showed developers the Stylus, later renamed ST-Pad, the ST-Pad was based on the TOS/GEM Atari ST Platform and prototyped early handwriting recognition. Shiraz Shivjis company Momentus demonstrated in the time a failed x86 MS-DOS based Pen Computer with its own GUI. In 1994, the European Union initiated the NewsPad project, inspired by Clarke, Acorn Computers developed and delivered an ARM-based touch screen tablet computer for this program, branding it the NewsPad, the project ended in 1997. During the November 2000 COMDEX, Microsoft used the term Tablet PC to describe a prototype handheld device they were demonstrating, all three products were based on extended versions of the MS-DOS operating system. In 1992, IBM announced and shipped to developers the 2521 ThinkPad, also based on PenPoint was AT&Ts EO Personal Communicator from 1993, which ran on AT&Ts own hardware, including their own AT&T Hobbit CPU. Apple Computer launched the Apple Newton personal digital assistant in 1993 and it utilised Apples own new Newton OS, initially running on hardware manufactured by Motorola and incorporating an ARM CPU, that Apple had specifically co-developed with Acorn Computers. The operating system and platform design were later licensed to Sharp and Digital Ocean, in 1996, Palm, Inc. released the first of the Palm OS based PalmPilot touch and stylus based PDA, the touch based devices initially incorporating a Motorola Dragonball CPU
3.
Smartphone
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A smartphone is a mobile phone with an advanced mobile operating system that combines features of a personal computer operating system with other features useful for mobile or handheld use. Smartphones can access the Internet and can run a variety of third-party software components and they typically have a color display with a graphical user interface that covers more than 76% of the front surface. In 1999, the Japanese firm NTT DoCoMo released the first smartphones to achieve mass adoption within a country, smartphones became widespread in the late 2000s. Most of those produced from 2012 onward have high-speed mobile broadband 4G LTE, motion sensors, in the third quarter of 2012, one billion smartphones were in use worldwide. Global smartphone sales surpassed the sales figures for regular cell phones in early 2013, devices that combined telephony and computing were first conceptualized by Nikola Tesla in 1909 and Theodore Paraskevakos in 1971 and patented in 1974, and were offered for sale beginning in 1993. Paraskevakos was the first to introduce the concepts of intelligence, data processing and they were installed at Peoples Telephone Company in Leesburg, Alabama and were demonstrated to several telephone companies. The original and historic working models are still in the possession of Paraskevakos, the first mobile phone to incorporate PDA features was a prototype developed by Frank Canova in 1992 while at IBM and demonstrated that year at the COMDEX computer industry trade show. It included PDA features and other mobile applications such as maps, stock reports. A refined version was marketed to consumers in 1994 by BellSouth under the name Simon Personal Communicator, the Simon was the first commercially available device that could be properly referred to as a smartphone, although it was not called that in 1994. The term smart phone appeared in print as early as 1995, in the mid-late 1990s, many mobile phone users carried a separate dedicated PDA device, running early versions of operating systems such as Palm OS, BlackBerry OS or Windows CE/Pocket PC. These operating systems would later evolve into mobile operating systems, in March 1996, Hewlett-Packard released the OmniGo 700LX, a modified HP 200LX palmtop PC that supported a Nokia 2110 phone with ROM-based software to support it. It had a 640×200 resolution CGA compatible four-shade gray-scale LCD screen and could be used to place and receive calls and it was also 100% DOS5.0 compatible, allowing it to run thousands of existing software titles, including early versions of Windows. In August 1996, Nokia released the Nokia 9000 Communicator, a cellular phone based on the Nokia 2110 with an integrated PDA based on the PEN/GEOS3.0 operating system from Geoworks. The two components were attached by a hinge in what known as a clamshell design, with the display above. The PDA provided e-mail, calendar, address book, calculator and notebook applications, text-based Web browsing, when closed, the device could be used as a digital cellular phone. In June 1999 Qualcomm released the pdQ Smartphone, a CDMA digital PCS Smartphone with an integrated Palm PDA, subsequent landmark devices included, The Ericsson R380 by Ericsson Mobile Communications. The first device marketed as a smartphone, it combined the functions of a phone and PDA. The Kyocera 6035 introduced by Palm, Inc, combining a PDA with a mobile phone, it operated on the Verizon network, and supported limited Web browsing
4.
Wearable computer
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Wearable computers, also known as body-borne computers or wearables are miniature electronic devices that are worn under, with or on top of clothing. This class of technology has been developed for general or special purpose information technologies. It is also used in media development, Wearable computers are especially useful for applications that require more complex computational support, such as accelerometers or gyroscopes, than just hardware coded logic. Wearable computing devices are variously defined, for example, consumers often refer to wearable computers as computers that can be easily carried on the body, or systems with a heads-up display or speech activated. This contrasts with academics that define wearables as a system that can perform a set of functions without being constrained by the hardware of the system. Merchandiser often use the broadest definition, as any computing device worn on the body and this article page will use the broadest definition. Smartwatches and the Fitbit system are the most common form, worn on the wrist, Google Glass is an optical head-mounted display supplying a augmented reality perspective, controlled by novel gestural movements. One common feature of wearable computers is their persistence of activity, there is constant interaction between the wearable and user, so there is no need to turn the device on or off. Another feature is the ability to multi-task, when using a wearable computer, there is no need to stop what one is doing to use the device, its functionality blends seamlessly into all other user actions. These devices can be used by the wearer to act as a prosthetic and it may therefore be an extension of the users mind or body. Many issues are common to wearables as with mobile computing, ambient intelligence, in many applications, the users body is actively engaged as the devices interface. This usually includes, the skin, hands, voice, eyes, Wearables are also receptive to any motion or attention. Wearable computer items have been developed and applied in the following, sensory integration, the use of wearables for specific applications, for compensating disabilities or supporting elderly people steadily increases. The application of computers in fashion design is evident through Microsofts prototype of The Printing Dress at the International Symposium on Wearable Computers in June 2011. However, a computer is not merely a time-keeping or calculating device, but rather a user-programmable item for complex algorithms, interfacing, Queen Elizabeth I of England received the wristwatch from Robert Dudley in 1571, as a new years present. The Qing Dynasty saw the introduction of a fully functional abacus on a ring, the first wearable timepiece was made by watchmaker Breguet for the Queen of Naples in 1810. It was a small pocket watch on a bracelet chain. A wristwatch is a computer in the sense that it can be worn
5.
Home automation
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Home automation or smart home is building automation for the home. It involves the control and automation of lighting, heating, ventilation, air conditioning, wi-Fi is often used for remote monitoring and control. Home devices, when remotely monitored and controlled via the Internet, are an important constituent of the Internet of Things, while there are many competing vendors, there are very few world-wide accepted industry standards and the smart home space is heavily fragmented. Popular communications protocol for products include X10, Ethernet, RS-485, 6LoWPAN, Bluetooth LE, ZigBee and Z-Wave, manufacturers often prevent independent implementations by withholding documentation and by litigation. The home automation market was worth US$5.77 billion in 2015, early home automation began with labor-saving machines. In 1975, the first general purpose home automation network technology and it is a communication protocol for electronic devices. It primarily uses electric power transmission wiring for signalling and control, where the signals involve brief radio frequency bursts of digital data, by 1978, X10 products included a 16 channel command console, a lamp module, and an appliance module. Soon after came the wall switch module and the first X10 timer, by 2012, in the United States, according to ABI Research,1.5 million home automation systems were installed. The word domotics is a contraction of the Latin word for a home, heating, ventilation and air conditioning, it is possible to have remote control of all home energy monitors over the internet incorporating a simple and friendly user interface. Technology is still in its infancy, and consumers could invest in a system that becomes abandonware. In 2014, Google bought the company selling the Revolv Hub home automation system, integrated it with Nest and in 2016 shut down the servers Revolv Hub depended on, rendering the hardware useless. Microsoft Research found in 2011, that home automation could involve high cost of ownership, inflexibility of interconnected devices, however, there are now open source software systems which can be used with proprietary hardware. There are a variety of technology platforms, or protocols. Each one is, essentially, its own language, each language speaks to the various connected devices and instructs them to perform a function. The automation protocol transport has involved direct wire connectivity, powerline and wireless hybrid, most of the protocols below are not open. Customers may be hesitant to bet their IoT future on proprietary software or hardware devices that use proprietary protocols that may fade or become difficult to customize and interconnect. The nature of home automation devices can also be a problem for security, since patches to bugs found in the operating system often do not reach users of older. One set of researchers say that the failure of vendors to support devices with patches and updates leaves more than 87% of active devices vulnerable
6.
ARM architecture
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ARM, originally Acorn RISC Machine, later Advanced RISC Machine, is a family of reduced instruction set computing architectures for computer processors, configured for various environments. It also designs cores that implement this instruction set and licenses these designs to a number of companies that incorporate those core designs into their own products, a RISC-based computer design approach means processors require fewer transistors than typical complex instruction set computing x86 processors in most personal computers. This approach reduces costs, heat and power use and these characteristics are desirable for light, portable, battery-powered devices—including smartphones, laptops and tablet computers, and other embedded systems. For supercomputers, which large amounts of electricity, ARM could also be a power-efficient solution. ARM Holdings periodically releases updates to architectures and core designs, some older cores can also provide hardware execution of Java bytecodes. The ARMv8-A architecture, announced in October 2011, adds support for a 64-bit address space, with over 100 billion ARM processors produced as of 2017, ARM is the most widely used instruction set architecture in terms of quantity produced. Currently, the widely used Cortex cores, older classic cores, the British computer manufacturer Acorn Computers first developed the Acorn RISC Machine architecture in the 1980s to use in its personal computers. Its first ARM-based products were coprocessor modules for the BBC Micro series of computers, according to Sophie Wilson, all the tested processors at that time performed about the same, with about a 4 Mbit/second bandwidth. After testing all available processors and finding them lacking, Acorn decided it needed a new architecture, inspired by white papers on the Berkeley RISC project, Acorn considered designing its own processor. Wilson developed the set, writing a simulation of the processor in BBC BASIC that ran on a BBC Micro with a 6502 second processor. This convinced Acorn engineers they were on the right track, Wilson approached Acorns CEO, Hermann Hauser, and requested more resources. Hauser gave his approval and assembled a team to implement Wilsons model in hardware. The official Acorn RISC Machine project started in October 1983 and they chose VLSI Technology as the silicon partner, as they were a source of ROMs and custom chips for Acorn. Wilson and Furber led the design and they implemented it with a similar efficiency ethos as the 6502. A key design goal was achieving low-latency input/output handling like the 6502, the 6502s memory access architecture had let developers produce fast machines without costly direct memory access hardware. The first samples of ARM silicon worked properly when first received and tested on 26 April 1985, Wilson subsequently rewrote BBC BASIC in ARM assembly language. The in-depth knowledge gained from designing the instruction set enabled the code to be very dense, the original aim of a principally ARM-based computer was achieved in 1987 with the release of the Acorn Archimedes. In 1992, Acorn once more won the Queens Award for Technology for the ARM, the ARM2 featured a 32-bit data bus, 26-bit address space and 27 32-bit registers
7.
X86
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X86 is a family of backward-compatible instruction set architectures based on the Intel 8086 CPU and its Intel 8088 variant. The term x86 came into being because the names of several successors to Intels 8086 processor end in 86, many additions and extensions have been added to the x86 instruction set over the years, almost consistently with full backward compatibility. The architecture has been implemented in processors from Intel, Cyrix, AMD, VIA and many companies, there are also open implementations. In the 1980s and early 1990s, when the 8088 and 80286 were still in common use, today, however, x86 usually implies a binary compatibility also with the 32-bit instruction set of the 80386. An 8086 system, including such as 8087 and 8089. There were also terms iRMX, iSBC, and iSBX – all together under the heading Microsystem 80, however, this naming scheme was quite temporary, lasting for a few years during the early 1980s. Today, x86 is ubiquitous in both stationary and portable computers, and is also used in midrange computers, workstations, servers. A large amount of software, including operating systems such as DOS, Windows, Linux, BSD, Solaris and macOS, functions with x86-based hardware. There have been attempts, including by Intel itself, to end the market dominance of the inelegant x86 architecture designed directly from the first simple 8-bit microprocessors. Examples of this are the iAPX432, the Intel 960, Intel 860, however, the continuous refinement of x86 microarchitectures, circuitry and semiconductor manufacturing would make it hard to replace x86 in many segments. The table below lists processor models and model series implementing variations of the x86 instruction set, each line item is characterized by significantly improved or commercially successful processor microarchitecture designs. Such x86 implementations are seldom simple copies but often employ different internal microarchitectures as well as different solutions at the electronic, quite naturally, early compatible microprocessors were 16-bit, while 32-bit designs were developed much later. For the personal computer market, real quantities started to appear around 1990 with i386 and i486 compatible processors, other companies, which designed or manufactured x86 or x87 processors, include ITT Corporation, National Semiconductor, ULSI System Technology, and Weitek. Some early versions of these microprocessors had heat dissipation problems, AMD later managed to establish itself as a serious contender with the K6 set of processors, which gave way to the very successful Athlon and Opteron. There were also other contenders, such as Centaur Technology, Rise Technology, VIA Technologies energy efficient C3 and C7 processors, which were designed by the Centaur company, have been sold for many years. Centaurs newest design, the VIA Nano, is their first processor with superscalar and it was, perhaps interestingly, introduced at about the same time as Intels first in-order processor since the P5 Pentium, the Intel Atom. The instruction set architecture has twice been extended to a word size. In 1999-2003, AMD extended this 32-bit architecture to 64 bits and referred to it as x86-64 in early documents, Intel soon adopted AMDs architectural extensions under the name IA-32e, later using the name EM64T and finally using Intel 64
8.
User interface
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The user interface, in the industrial design field of human–computer interaction, is the space where interactions between humans and machines occur. Examples of this concept of user interfaces include the interactive aspects of computer operating systems, hand tools, heavy machinery operator controls. The design considerations applicable when creating user interfaces are related to or involve such disciplines as ergonomics and psychology. Generally, the goal of user interface design is to produce a user interface makes it easy, efficient. This generally means that the needs to provide minimal input to achieve the desired output. Other terms for user interface are man–machine interface and when the machine in question is a computer human–computer interface, the user interface or human–machine interface is the part of the machine that handles the human–machine interaction. Membrane switches, rubber keypads and touchscreens are examples of the part of the Human Machine Interface which we can see. In complex systems, the interface is typically computerized. The term human–computer interface refers to this kind of system, in the context of computing the term typically extends as well to the software dedicated to control the physical elements used for human-computer interaction. The engineering of the interfaces is enhanced by considering ergonomics. The corresponding disciplines are human factors engineering and usability engineering, which is part of systems engineering, tools used for incorporating human factors in the interface design are developed based on knowledge of computer science, such as computer graphics, operating systems, programming languages. Nowadays, we use the graphical user interface for human–machine interface on computers. There is a difference between a user interface and an interface or a human–machine interface. A human-machine interface is typically local to one machine or piece of equipment, an operator interface is the interface method by which multiple equipment that are linked by a host control system is accessed or controlled. The system may expose several user interfaces to serve different kinds of users, for example, a computerized library database might provide two user interfaces, one for library patrons and the other for library personnel. The user interface of a system, a vehicle or an industrial installation is sometimes referred to as the human–machine interface. HMI is a modification of the original term MMI, in practice, the abbreviation MMI is still frequently used although some may claim that MMI stands for something different now. Another abbreviation is HCI, but is commonly used for human–computer interaction
9.
Digital camera
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A digital camera or digicam is a camera that produces digital images that can be stored in a computer, displayed on a screen and printed. Most cameras sold today are digital, and digital cameras are incorporated into many devices ranging from PDAs, Digital and movie cameras share an optical system, typically using a lens with a variable diaphragm to focus light onto an image pickup device. The diaphragm and shutter admit the correct amount of light to the imager, just as with film, however, unlike film cameras, digital cameras can display images on a screen immediately after being recorded, and store and delete images from memory. Many digital cameras can also record moving videos with sound, some digital cameras can crop and stitch pictures and perform other elementary image editing. The history of the camera began with Eugene F. Lally of the Jet Propulsion Laboratory. His 1961 idea was to take pictures of the planets and stars while travelling through space to give information about the astronauts position, unfortunately, as with Texas Instruments employee Willis Adcocks filmless camera in 1972, the technology had yet to catch up with the concept. Steven Sasson as an engineer at Eastman Kodak invented and built the first electronic camera using a charge-coupled device image sensor in 1975, earlier ones used a camera tube, later ones digitized the signal. Early uses were military and scientific, followed by medical. In the mid to late 1990s digital cameras became common among consumers, by the mid-2000s digital cameras had largely replaced film cameras, and higher-end cell phones had an integrated digital camera. By the beginning of the 2010s, almost all smartphones had a digital camera. The two major types of image sensor are CCD and CMOS. A CCD sensor has one amplifier for all the pixels, while each pixel in a CMOS active-pixel sensor has its own amplifier, compared to CCDs, CMOS sensors use less power. Cameras with a small sensor use a back-side-illuminated CMOS sensor, overall final image quality is more dependent on the image processing capability of the camera, than on sensor type. The resolution of a camera is often limited by the image sensor that turns light into that discrete signals. The brighter the image at a point on the sensor. Depending on the structure of the sensor, a color filter array may be used. The number of pixels in the sensor determines the cameras pixel count, in a typical sensor, the pixel count is the product of the number of rows and the number of columns. For example, a 1,000 by 1,000 pixel sensor would have 1,000,000 pixels, final quality of an image depends on all optical transformations in the chain of producing the image
10.
Smartwatch
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A smartwatch is a computerized wristwatch with functionality that goes beyond timekeeping. While early models can perform tasks, such as calculations, translations. Many run mobile apps, using an operating system. Some smartwatches function as media players, with FM radio and playback of digital audio. Some models, also called watch phones, feature full mobile phone capability, while internal hardware varies, most have an electronic visual display, either backlit LCD or OLED. Some use transflective or electronic paper, to less power. Most have a battery and many have a touchscreen. Peripheral devices may include digital cameras, thermometers, accelerometers, altimeters, barometers, compasses, GPS receivers, tiny speakers, software may include digital maps, schedulers and personal organizers, calculators, and various kinds of watch faces. The watch may communicate with devices such as sensors, wireless headsets. Like other computers, a smartwatch may collect information from internal or external sensors and it may control, or retrieve data from and it may support wireless technologies like Bluetooth, Wi-Fi, and GPS. For many purposes, a wristwatch computer serves as a front end for a system such as a smartphone. Smartwatches are advancing, especially their design, battery capacity, many smartwatch models manufactured in the 2010s are completely functional as standalone products. Some serve as sport watches, the GPS tracking unit being used to record historical data, for example, after a workout, data can be uploaded onto a computer or online to create a log of activities for analysis or sharing. Some watches can serve as full GPS watches, displaying maps and current coordinates, users can mark their current location and then edit the entrys name and coordinates, which enables navigation to those new coordinates. As companies add competitive products into the market, media space is becoming a commodity on smart watches. With Apple, Sony, Samsung, and Motorola introducing their smart watch models and this is a dense market of tech consumers who possess buying power, which has attracted many advertisers. It is expected for mobile advertising on wearable devices to increase heavily by 2017 as advanced hypertargeting modules are introduced to the devices. In order for an advertisement to be effective on a smart watch, sport watch functionality often includes activity tracker features as seen in GPS watches made for training, diving, and outdoor sports
11.
DVD player
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A DVD player is a device that plays discs produced under both the DVD-Video and DVD-Audio technical standards, two different and incompatible standards. Some DVD players will also play audio CDs, DVD players are connected to a television to watch the DVD content, which could be a movie, a recorded TV show, or other content. The first DVD player was created by Sony Company in Taiwan in collaboration with Pacific Digital Company from the United States in 1994, some manufacturers originally announced that DVD players would be available as early as the middle of 1996. Delivery was initially held up for reasons of copy protection demanded by movie studios. The first players appeared in Japan in November 1,1996, players slowly trickled into other regions around the world. Prices for the first players in 1997 were $1000 and up, by the end of 2000, players were available for under $100 at discount retailers. In 2003 players became available for under $50, six years after the initial launch, close to one thousand models of DVD players were available from over a hundred consumer electronics manufacturers. Fujitsu released the first DVD-ROM-equipped computer on Nov.6 in GB, Toshiba released a DVD-ROM-equipped computer and a DVD-ROM drive in Japan in early 1997. DVD-ROM drives from Toshiba, Pioneer, Panasonic, Hitachi, and Sony began appearing in sample quantities as early as January 1997, the first PC upgrade kits became available from Creative Labs, Hi-Val, and Diamond Multimedia in April and May 1997. In 2014, every major PC manufacturer has models that include DVD-ROM drives, the first DVD-Audio players were released in Japan by Pioneer in late 1999, but they did not play copy-protected discs. Matsushita first released full-fledged players in July 2000 for $700 to $1,200, DVD-Audio players are now also made by Aiwa, Denon, JVC, Kenwood, Madrigal, Marantz, Nakamichi, Onkyo, Toshiba, Yamaha, and others. Sony released the first SACD players in May 1999 for $5,000, pioneers first DVD-Audio players released in late 1999 also played SACD. SACD players are now made by Accuphase, Aiwa, Denon, Kenwood, Marantz, Philips, Sharp. A DVD player has to complete tasks, Read a DVD disc in ISO – UDF version 1. DVD players cannot play Blu-ray discs, however, most Blu-ray players are backwards compatible and they will play DVDs. Additionally, most DVD players allow users to play audio CDs, a few include a home cinema decoder. Some newer devices also play videos in the MPEG-4 ASP video compression format popular in the Internet, most hardware DVD players have to be connected to a television, there are portable devices which have an attached LCD screen and stereo speakers. Portable DVD players are used for long road trips and travel
12.
Refrigerator
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Refrigeration is an essential food storage technique in developed countries. The lower temperature lowers the rate of bacteria, so the refrigerator reduces the rate of spoilage. A refrigerator maintains a temperature a few degrees above the point of water. Optimum temperature range for food storage is 3 to 5 °C. A similar device that maintains a temperature below the point of water is called a freezer. The refrigerator replaced the icebox, which had been a household appliance for almost a century. For this reason, a refrigerator is sometimes referred to as an icebox in American usage, the first cooling systems for food involved using ice. Artificial refrigeration began in the mid-1750s, and developed in the early 1800s, in 1834, the first working vapor-compression refrigeration system was built. The first commercial ice-making machine was invented in 1854, in 1913, refrigerators for home use were invented. In 1923 Frigidaire introduced the first self-contained unit, the introduction of Freon in the 1920s expanded the refrigerator market during the 1930s. Home freezers as separate compartments were introduced in 1940, frozen foods, previously a luxury item, became commonplace. Freezer units are used in households and in industry and commerce, commercial refrigerator and freezer units were in use for almost 40 years prior to the common home models. Most households use the style, which has been the basic style since the 1940s. A vapor compression cycle is used in most household refrigerators, refrigerator–freezers and freezers, newer refrigerators may include automatic defrosting, chilled water and ice from a dispenser in the door. Domestic refrigerators and freezers for food storage are made in a range of sizes, among the smallest is a 4 L Peltier refrigerator advertised as being able to hold 6 cans of beer. A large domestic refrigerator stands as tall as a person and may be about 1 m wide with a capacity of 600 L. Refrigerators and freezers may be free-standing, the refrigerator allows the modern household to keep food fresh for longer than before. Freezers allow people to buy food in bulk and eat it at leisure, before the invention of the refrigerator, icehouses were used to provide cool storage for most of the year. Placed near freshwater lakes or packed snow and ice during the winter
