A mobile phone, cell phone, cellphone, or hand phone, sometimes shortened to mobile, cell or just phone, is a portable telephone that can make and receive calls over a radio frequency link while the user is moving within a telephone service area. The radio frequency link establishes a connection to the switching systems of a mobile phone operator, which provides access to the public switched telephone network. Modern mobile telephone services use a cellular network architecture, therefore, mobile telephones are called cellular telephones or cell phones, in North America. In addition to telephony, 2000s-era mobile phones support a variety of other services, such as text messaging, MMS, Internet access, short-range wireless communications, business applications, video games, digital photography. Mobile phones offering only those capabilities are known as feature phones; the first handheld mobile phone was demonstrated by John F. Mitchell and Martin Cooper of Motorola in 1973, using a handset weighing c. 2 kilograms.
In 1979, Nippon Telegraph and Telephone launched the world's first cellular network in Japan. In 1983, the DynaTAC 8000x was the first commercially available handheld mobile phone. From 1983 to 2014, worldwide mobile phone subscriptions grew to over seven billion—enough to provide one for every person on Earth. In first quarter of 2016, the top smartphone developers worldwide were Samsung and Huawei, smartphone sales represented 78 percent of total mobile phone sales. For feature phones as of 2016, the largest were Samsung and Alcatel. A handheld mobile radio telephone service was envisioned in the early stages of radio engineering. In 1917, Finnish inventor Eric Tigerstedt filed a patent for a "pocket-size folding telephone with a thin carbon microphone". Early predecessors of cellular phones included analog radio communications from trains; the race to create portable telephone devices began after World War II, with developments taking place in many countries. The advances in mobile telephony have been traced in successive "generations", starting with the early zeroth-generation services, such as Bell System's Mobile Telephone Service and its successor, the Improved Mobile Telephone Service.
These 0G systems were not cellular, supported few simultaneous calls, were expensive. The first handheld cellular mobile phone was demonstrated by John F. Mitchell and Martin Cooper of Motorola in 1973, using a handset weighing 2 kilograms; the first commercial automated cellular network analog was launched in Japan by Nippon Telegraph and Telephone in 1979. This was followed in 1981 by the simultaneous launch of the Nordic Mobile Telephone system in Denmark, Finland and Sweden. Several other countries followed in the early to mid-1980s; these first-generation systems could support far more simultaneous calls but still used analog cellular technology. In 1983, the DynaTAC 8000x was the first commercially available handheld mobile phone. In 1991, the second-generation digital cellular technology was launched in Finland by Radiolinja on the GSM standard; this sparked competition in the sector as the new operators challenged the incumbent 1G network operators. Ten years in 2001, the third generation was launched in Japan by NTT DoCoMo on the WCDMA standard.
This was followed by 3.5G, 3G+ or turbo 3G enhancements based on the high-speed packet access family, allowing UMTS networks to have higher data transfer speeds and capacity. By 2009, it had become clear that, at some point, 3G networks would be overwhelmed by the growth of bandwidth-intensive applications, such as streaming media; the industry began looking to data-optimized fourth-generation technologies, with the promise of speed improvements up to ten-fold over existing 3G technologies. The first two commercially available technologies billed as 4G were the WiMAX standard, offered in North America by Sprint, the LTE standard, first offered in Scandinavia by TeliaSonera. 5G is a technology and term used in research papers and projects to denote the next major phase in mobile telecommunication standards beyond the 4G/IMT-Advanced standards. The term 5G is not used in any specification or official document yet made public by telecommunication companies or standardization bodies such as 3GPP, WiMAX Forum or ITU-R.
New standards beyond 4G are being developed by standardization bodies, but they are at this time seen as under the 4G umbrella, not for a new mobile generation. Smartphones have a number of distinguishing features; the International Telecommunication Union measures those with Internet connection, which it calls Active Mobile-Broadband subscriptions. In the developed world, smartphones have now overtaken the usage of earlier mobile systems. However, in the developing world, they account for around 50% of mobile telephony. Feature phone is a term used as a retronym to describe mobile phones which are limited in capabilities in contrast to a modern smartphone. Feature phones provide voice calling and text messaging functionality, in addition to basic multimedia and Internet capabilities, other services offered by the user's wireless service provider. A feature phone has additional functions over and above a basic mobile phone, only capable of voice calling and text messaging. Feature phones and basic mobile phones tend to use a proprietary, custom-designed software and user interface.
By contrast, smartphones use a mobile operating system that shares common traits across devices. There are Orthodox Jewish religious re
China the People's Republic of China, is a country in East Asia and the world's most populous country, with a population of around 1.404 billion. Covering 9,600,000 square kilometers, it is the third- or fourth-largest country by total area. Governed by the Communist Party of China, the state exercises jurisdiction over 22 provinces, five autonomous regions, four direct-controlled municipalities, the special administrative regions of Hong Kong and Macau. China emerged as one of the world's earliest civilizations, in the fertile basin of the Yellow River in the North China Plain. For millennia, China's political system was based on hereditary monarchies, or dynasties, beginning with the semi-legendary Xia dynasty in 21st century BCE. Since China has expanded, re-unified numerous times. In the 3rd century BCE, the Qin established the first Chinese empire; the succeeding Han dynasty, which ruled from 206 BC until 220 AD, saw some of the most advanced technology at that time, including papermaking and the compass, along with agricultural and medical improvements.
The invention of gunpowder and movable type in the Tang dynasty and Northern Song completed the Four Great Inventions. Tang culture spread in Asia, as the new Silk Route brought traders to as far as Mesopotamia and Horn of Africa. Dynastic rule ended in 1912 with the Xinhai Revolution; the Chinese Civil War resulted in a division of territory in 1949, when the Communist Party of China established the People's Republic of China, a unitary one-party sovereign state on Mainland China, while the Kuomintang-led government retreated to the island of Taiwan. The political status of Taiwan remains disputed. Since the introduction of economic reforms in 1978, China's economy has been one of the world's fastest-growing with annual growth rates above 6 percent. According to the World Bank, China's GDP grew from $150 billion in 1978 to $12.24 trillion by 2017. Since 2010, China has been the world's second-largest economy by nominal GDP and since 2014, the largest economy in the world by purchasing power parity.
China is the world's largest exporter and second-largest importer of goods. China is a recognized nuclear weapons state and has the world's largest standing army and second-largest defense budget; the PRC is a permanent member of the United Nations Security Council as it replaced the ROC in 1971, as well as an active global partner of ASEAN Plus mechanism. China is a leading member of numerous formal and informal multilateral organizations, including the Shanghai Cooperation Organization, WTO, APEC, BRICS, the BCIM, the G20. In recent times, scholars have argued that it will soon be a world superpower, rivaling the United States; the word "China" has been used in English since the 16th century. It is not a word used by the Chinese themselves, it has been traced through Portuguese and Persian back to the Sanskrit word Cīna, used in ancient India."China" appears in Richard Eden's 1555 translation of the 1516 journal of the Portuguese explorer Duarte Barbosa. Barbosa's usage was derived from Persian Chīn, in turn derived from Sanskrit Cīna.
Cīna was first used including the Mahābhārata and the Laws of Manu. In 1655, Martino Martini suggested that the word China is derived from the name of the Qin dynasty. Although this derivation is still given in various sources, it is complicated by the fact that the Sanskrit word appears in pre-Qin literature; the word may have referred to a state such as Yelang. The meaning transferred to China as a whole; the origin of the Sanskrit word is still a matter of debate, according to the Oxford English Dictionary. The official name of the modern state is the "People's Republic of China"; the shorter form is "China" Zhōngguó, from zhōng and guó, a term which developed under the Western Zhou dynasty in reference to its royal demesne. It was applied to the area around Luoyi during the Eastern Zhou and to China's Central Plain before being used as an occasional synonym for the state under the Qing, it was used as a cultural concept to distinguish the Huaxia people from perceived "barbarians". The name Zhongguo is translated as "Middle Kingdom" in English.
Archaeological evidence suggests that early hominids inhabited China between 2.24 million and 250,000 years ago. The hominid fossils of Peking Man, a Homo erectus who used fire, were discovered in a cave at Zhoukoudian near Beijing; the fossilized teeth of Homo sapiens have been discovered in Fuyan Cave in Hunan. Chinese proto-writing existed in Jiahu around 7000 BCE, Damaidi around 6000 BCE, Dadiwan from 5800–5400 BCE, Banpo dating from the 5th millennium BCE; some scholars have suggested. According to Chinese tradition, the first dynasty was the Xia, which emerged around 2100 BCE; the dynasty was considered mythical by historians until scientific excavations found early Bronze Age sites at Erlitou, Henan in 1959. It remains unclear whether these sites are the remains of the Xia dynasty or of another culture from the same period; the succeeding Shang dynasty is the earliest to be confirmed by contemporary records. The Shang ruled the plain of the Yellow River in eastern China from the 17th to the 11th century BCE.
Their oracle bone script
Dung beetles are beetles that feed or on feces. A dung beetle can bury dung 250 times heavier than itself in one night. Many dung beetles, known as rollers, roll dung into round balls, which are used as a food source or breeding chambers. Others, known as tunnelers, bury the dung. A third group, the dwellers, neither roll nor burrow: they live in manure, they are attracted by the dung collected by burrowing owls. There are dung beetle species of different colours and sizes, some functional traits such as body mass and leg length can have high levels of variability. All the species belong to the superfamily Scarabaeoidea; as most species of Scarabaeinae feed on feces, that subfamily is dubbed true dung beetles. There are dung-feeding beetles, such as the Geotrupidae; the Scarabaeinae alone comprises more than 5,000 species. The nocturnal African dung beetle Scarabaeus satyrus is the only known non-vertebrate animal to navigate and orient itself using the Milky Way. Dung beetles are not a single taxonomic group.
Coleoptera, beetles Scarabaeoidea, scarabs Geotrupidae, "earth-boring dung beetles" Scarabaeidae, "scarab beetles" Scarabaeinae, "true dung beetles" Aphodiinae, "small dung beetles" Systematic Position: Kingdom Animalia Phylum Arthropoda Subphylum Hexapoda Class Insecta Order Coleoptera Suborder Polyphaga Superfamily Scarabaeoidea Family Scarabaeidae ↑ Dung beetles live in many habitats, including desert and savannas, native and planted forests. They are influenced by the environmental context, do not prefer cold or dry weather, they are found on all continents except Antarctica. They eat the dung of herbivores and omnivores, prefer that produced by the latter. Many of them feed on mushrooms and decaying leaves and fruits. One type living in Central America, Deltochilum valgum, is a carnivore preying upon millipedes; those that eat dung do not need to eat or drink anything else, because the dung provides all the necessary nutrients. Most dung beetles search for dung using their sensitive sense of smell.
Some smaller species attach themselves to the dung-providers to wait for the dung. After capturing the dung, a dung beetle rolls it. Sometimes, dung beetles try to steal the dung ball from another beetle, so the dung beetles have to move away from a dung pile once they have rolled their ball to prevent it from being stolen. Dung beetles can roll up to 10 times their weight. Male Onthophagus taurus beetles can pull 1,141 times their own body weight: the equivalent of an average person pulling six double-decker buses full of people. A species of dung beetle navigates by polarization patterns in moonlight, the first animal known to do so. Dung beetles can navigate when only the Milky Way or clusters of bright stars are visible, making them the only insects known to orient themselves by the Milky Way; the eyes of dung beetles are superposition compound eyes typical of many scarabaeid beetles. The "rollers" bury a dung ball either for food storage or for making a brooding ball. In the latter case, two beetles, one male and one female, stay around the dung ball during the rolling process.
It is the male that rolls the ball, while the female hitch-hikes or follows behind. In some cases, the male and the female roll together; when a spot with soft soil is found, they stop and bury the ball mate underground. After the mating, one or both of them prepares the brooding ball; when the ball is finished, the female lays eggs inside it, a form of mass provisioning. Some species remain to safeguard their offspring; the dung beetle goes through a complete metamorphosis. The larvae live in brood balls made with dung prepared by their parents. During the larval stage, the beetle feeds on the dung surrounding it; the behavior of the beetles was poorly understood until the studies of Jean Henri Fabre in the late 19th century. For example, Fabre corrected the myth that a dung beetle would seek aid from other dung beetles when confronted by obstacles. By observation and experiment, he found the seeming helpers were in fact awaiting an opportunity to steal the roller's food source, they are used in ecological research as a good bioindicator group to examine the impacts from human activities on tropical biodiversity and ecosystem functioning, such as seed dispersal, soil bioturbation and nutrient cycling.
Dung beetles play a remarkable role in agriculture and tropical forests. By burying and consuming dung, they improve soil structure. Dung beetles have been further shown to improv
Europe is a continent located in the Northern Hemisphere and in the Eastern Hemisphere. It is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west and the Mediterranean Sea to the south, it comprises the westernmost part of Eurasia. Since around 1850, Europe is most considered to be separated from Asia by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas and the waterways of the Turkish Straits. Although the term "continent" implies physical geography, the land border is somewhat arbitrary and has been redefined several times since its first conception in classical antiquity; the division of Eurasia into two continents reflects East-West cultural and ethnic differences which vary on a spectrum rather than with a sharp dividing line. The geographic border does not follow political boundaries, with Turkey and Kazakhstan being transcontinental countries. A strict application of the Caucasus Mountains boundary places two comparatively small countries and Georgia, in both continents.
Europe covers 2 % of the Earth's surface. Politically, Europe is divided into about fifty sovereign states of which the Russian Federation is the largest and most populous, spanning 39% of the continent and comprising 15% of its population. Europe had a total population of about 741 million as of 2016; the European climate is affected by warm Atlantic currents that temper winters and summers on much of the continent at latitudes along which the climate in Asia and North America is severe. Further from the sea, seasonal differences are more noticeable than close to the coast. Europe, in particular ancient Greece, was the birthplace of Western civilization; the fall of the Western Roman Empire in 476 AD and the subsequent Migration Period marked the end of ancient history and the beginning of the Middle Ages. Renaissance humanism, exploration and science led to the modern era. Since the Age of Discovery started by Portugal and Spain, Europe played a predominant role in global affairs. Between the 16th and 20th centuries, European powers controlled at various times the Americas all of Africa and Oceania and the majority of Asia.
The Age of Enlightenment, the subsequent French Revolution and the Napoleonic Wars shaped the continent culturally and economically from the end of the 17th century until the first half of the 19th century. The Industrial Revolution, which began in Great Britain at the end of the 18th century, gave rise to radical economic and social change in Western Europe and the wider world. Both world wars took place for the most part in Europe, contributing to a decline in Western European dominance in world affairs by the mid-20th century as the Soviet Union and the United States took prominence. During the Cold War, Europe was divided along the Iron Curtain between NATO in the West and the Warsaw Pact in the East, until the revolutions of 1989 and fall of the Berlin Wall. In 1949 the Council of Europe was founded, following a speech by Sir Winston Churchill, with the idea of unifying Europe to achieve common goals, it includes all European states except for Belarus and Vatican City. Further European integration by some states led to the formation of the European Union, a separate political entity that lies between a confederation and a federation.
The EU originated in Western Europe but has been expanding eastward since the fall of the Soviet Union in 1991. The currency of most countries of the European Union, the euro, is the most used among Europeans. In classical Greek mythology, Europa was a Phoenician princess; the word Europe is derived from her name. The name contains the elements εὐρύς, "wide, broad" and ὤψ "eye, countenance", hence their composite Eurṓpē would mean "wide-gazing" or "broad of aspect". Broad has been an epithet of Earth herself in the reconstructed Proto-Indo-European religion and the poetry devoted to it. There have been attempts to connect Eurṓpē to a Semitic term for "west", this being either Akkadian erebu meaning "to go down, set" or Phoenician'ereb "evening, west", at the origin of Arabic Maghreb and Hebrew ma'arav. Michael A. Barry, professor in Princeton University's Near Eastern Studies Department, finds the mention of the word Ereb on an Assyrian stele with the meaning of "night, sunset", in opposition to Asu " sunrise", i.e. Asia.
The same naming motive according to "cartographic convention" appears in Greek Ἀνατολή. Martin Litchfield West stated that "phonologically, the match between Europa's name and any form of the Semitic word is poor." Next to these hypotheses there is a Proto-Indo-European root *h1regʷos, meaning "darkness", which produced Greek Erebus. Most major world languages use words derived from Europa to refer to the continent. Chinese, for example, uses the word Ōuzhōu. In some Turkic languages the Persian name Frangistan is used casually in referring to much of Europe, besides official names such as Avrupa or Evropa; the prevalent definition of Europe as a geographical term has been in use since the mid-19th century. Europe is taken to be bounded by large bodies of water
The Atari ST is a line of home computers from Atari Corporation and the successor to the Atari 8-bit family. The initial ST model, the 520ST, saw limited release in April–June 1985 and was available in July; the Atari ST is the first personal computer to come with a bitmapped color GUI, using a version of Digital Research's GEM released in February 1985. The 1040ST, released in 1986, is the first personal computer to ship with a megabyte of RAM in the base configuration and the first with a cost-per-kilobyte of less than US$1; the Atari ST is part of a mid-1980s generation of home computers that have 16 or 32-bit processors, 256 KB or more of RAM, mouse-controlled graphical user interfaces. This generation includes the Macintosh, Commodore Amiga, Apple IIGS, and, in certain markets, the Acorn Archimedes. "ST" stands for "Sixteen/Thirty-two", which refers to the Motorola 68000's 16-bit external bus and 32-bit internals. The ST was sold with the less expensive monochrome monitor; the system's two color graphics modes are only available on the former while the highest-resolution mode needs the monochrome monitor.
In some markets Germany, the machine gained a strong foothold as a small business machine for CAD and desktop publishing work. Thanks to its built-in MIDI ports, the ST enjoyed success for running music-sequencer software and as a controller of musical instruments among amateurs and well-known musicians alike; the ST was superseded by the Atari STE, Atari TT, Atari MEGA STE, Falcon computers. The Atari ST was born from the rivalry between home-computer makers Atari, Inc. and Commodore International. Jay Miner, one of the original designers for the custom chips found in the Atari 2600 and Atari 8-bit family, tried to convince Atari management to create a new chipset for a video game console and computer; when his idea was rejected, Miner left Atari to form a small think tank called Hi-Toro in 1982 and began designing the new "Lorraine" chipset. The company, renamed Amiga Corporation, was pretending to sell video game controllers to deceive competition while it developed a Lorraine-based computer.
Amiga ran out of capital to complete Lorraine's development, Atari, owned by Warner Communications, paid Amiga to continue development work. In return Atari received exclusive use of the Lorraine design for one year as a video game console. After one year Atari would have the right to add a keyboard and market the complete computer, designated the 1850XLD; as Atari was involved with Disney at the time, it was code-named "Mickey", the 256K memory expansion board was codenamed "Minnie". After leaving Commodore International in January 1984, Jack Tramiel formed Tramel Technology with his sons and other ex-Commodore employees and, in April, began planning a new computer; the company considered the National Semiconductor NS320xx microprocessor but was disappointed with its performance. This started the move to the 68000; the lead designer of the Atari ST was ex-Commodore employee Shiraz Shivji, who had worked on the Commodore 64's development. Atari in mid-1984 was losing about a million dollars per day.
Interested in Atari's overseas manufacturing and worldwide distribution network for his new computer, Tramiel negotiated with Warner in May and June 1984. He bought Atari's Consumer Division in July; as executives and engineers left Commodore to join Tramiel's new Atari Corporation, Commodore responded by filing lawsuits against four former engineers for theft of trade secrets. The Tramiels did not purchase the employee contracts when they bought the assets of Atari Inc. so one of their first acts was to interview Atari Inc. employees to decide whom to hire at what was a brand new company. This company was called TTL renamed to Atari Corp. At the time of the purchase of Atari Inc's assets, there were 900 employees remaining from a high point of 10,000. After the interviews 100 employees were hired to work at Atari Corp. At one point a custom sound processor called AMY was a planned component for the new ST computer design, but the chip needed more time to complete, so AMY was dropped in favor of an off-the-shelf Yamaha sound chip.
It was during this time in late July/early August that Leonard Tramiel discovered the original Amiga contract, which required Amiga Corporation to deliver the Lorraine chipset to Atari on June 30, 1984. Amiga Corp. had sought more monetary support from investors in spring 1984. Having heard rumors that Tramiel was negotiating to buy Atari, Amiga Corp. entered into discussions with Commodore. The discussions led to Commodore wanting to purchase Amiga Corporation outright, which Commodore believed would cancel any outstanding contracts, including Atari's. Instead of Amiga Corp. delivering Lorraine to Atari, Commodore delivered a check of $500,000 to Atari on Amiga's behalf, in effect returning the funds Atari invested into Amiga for the chipset. Tramiel countersued Amiga Corp. on August 13, 1984. He sought an injunction to bar Amiga from producing anything with its technology. At Commodore, the Amiga team was in limbo during the summer of 1984 because of the lawsuit. No word on the status of the chipset, the Lorraine computer, or the team's fate was known.
In the fall of 1984, Commodore informed the team that the Lorraine project was active again, the chipset was to be improved, the operating system developed, the hardware design completed. While Commodore announced the Amiga 1000 with the Lorraine chipset in July 1985, the delay gave Atari, with its ma
Shoot 'em up
Shoot'em up is a subgenre of the shooter genre of video games. There is no consensus as to; some restrict the definition to games featuring spacecraft and certain types of character movement. The genre's roots can be traced back to Spacewar!, one of the earliest computer games, developed in 1962. The shoot'em up genre was established by the hit arcade game Space Invaders, which popularised and set the general template for the genre in 1978, the genre was further developed by arcade hits such as Asteroids and Galaxian in 1979. Shoot'em ups were popular throughout early 1990s. In the mid-1990s, shoot'em ups became a niche genre based on design conventions established in the 1980s, catered to specialist enthusiasts in Japan. "Bullet hell" games are a subgenre that features overwhelming numbers of enemy projectiles in visually impressive formations. A "shoot'em up" known as a "shmup" or "STG", is a game in which the protagonist combats a large number of enemies by shooting at them while dodging their fire.
The controlling player must rely on reaction times to succeed. Beyond this, critics differ on which design elements constitute a shoot'em up; some restrict the genre to games using fixed or scrolling movement. Others widen the scope to include games featuring such protagonists as robots or humans on foot, as well as including games featuring "on-rails" and "run and gun" movement. Mark Wolf restricts the definition to games featuring multiple antagonists, calling games featuring one-on-one shooting "combat games". Critics described any game where the primary design element was shooting as a "shoot'em up", but shoot'em ups became a specific, inward-looking genre based on design conventions established in those shooting games of the 1980s. Shoot'em ups are a subgenre of shooter game, in turn a type of action game; these games are viewed from a top-down or side-view perspective, players must use ranged weapons to take action at a distance. The player's avatar is a vehicle under constant attack. Thus, the player's goal is to shoot as as possible at anything that moves or threatens them.
In some games, the player's character can withstand some damage. The main skills required in shoot'em ups are memorising enemy attack patterns; some games feature overwhelming numbers of enemy projectiles and the player has to memorise their patterns to survive. These games belong to one of the fastest-paced video game genres. Large numbers of enemy characters are featured; these enemies may behave in a certain way dependent on their type, or attack in formations that the player can learn to predict. The basic gameplay tends to be straightforward and many games offset this with boss battles and a variety of weapons. Shoot'em ups have realistic physics. Characters can change direction with no inertia, projectiles move in a straight line at constant speeds; the player's character can collect "power-ups" which may afford the character greater protection, an "extra life", or upgraded weaponry. Different weapons are suited to different enemies, but these games keep track of ammunition; as such, players tend to fire indiscriminately, their weapons only damage legitimate targets.
Shoot'em ups are categorized by design elements viewpoint and movement:Fixed shooters restrict the protagonist to a single axis of motion, enemies attack in a single direction, each level is contained within a single screen. Atari's Centipede is a hybrid, in that the player can move but that movement is constrained to a small area at the bottom of the screen, the game otherwise meets the fixed shooter definition. Tube shooters feature craft flying through an abstract tube, such as Gyruss. Rail shooters limit the player to moving around the screen. Examples include Space Harrier, Captain Skyhawk, Star Wars: Rebel Assault, Panzer Dragoon, Star Fox 64, Sin and Punishment. Light-Gun games that are "on-rails" are not in the shoot-em-up category but the FPS category, the term has been applied to scripted events in first-person shooters such as Call of Duty. Scrolling shooters include horizontal scrolling games. Vertically scrolling shooters: In a vertically scrolling shoot'em up, the action is viewed from above and scrolls up the screen.
Horizontally scrolling shooters: In a "horizontal shooter" or "side-scrolling shooter", the action is viewed side-on and scrolls horizontally. Isometrically scrolling shooters: A small number of scrolling shooters, such as Sega's Zaxxon, feature an isometric point of view. Multidirectional shooters feature 360 degree movement where the protagonist may rotate and move in any direction. Multidirectional shooters with one joystick for movement and one joystick for firing in any direction independent of movement are called "twin-stick shooters."Bullet hell is a shoot'em up in which the entire screen is almost fille
The ZX Spectrum is an 8-bit personal home computer released in the United Kingdom in 1982 by Sinclair Research. Referred to during development as the ZX81 Colour and ZX82, it was launched as the ZX Spectrum by Sinclair to highlight the machine's colour display, compared with the black and white of its predecessor, the ZX81; the Spectrum was released as eight different models, ranging from the entry level with 16 KB RAM released in 1982 to the ZX Spectrum +3 with 128 KB RAM and built in floppy disk drive in 1987. The Spectrum was among the first mainstream-audience home computers in the UK, similar in significance to the Commodore 64 in the US; the introduction of the ZX Spectrum led to a boom in companies producing software and hardware for the machine, the effects of which are still seen. Some credit it as the machine. Licensing deals and clones followed, earned Clive Sinclair a knighthood for "services to British industry"; the Commodore 64, Dragon 32, Oric-1, Oric Atmos, BBC Micro and the Amstrad CPC range were rivals to the Spectrum in the UK market during the early 1980s.
While the machine was discontinued in 1992, new software titles continue to be released – over 40 so far in 2018. The Spectrum is based on a Zilog Z80 A CPU running at 3.5 MHz. The original model has 16 KB of ROM and either 16 KB or 48 KB of RAM. Hardware design was by Richard Altwasser of Sinclair Research, the outward appearance was designed by Sinclair's industrial designer Rick Dickinson. Video output is through an RF modulator and was designed for use with contemporary television sets, for a simple colour graphic display. Text can be displayed using 32 columns × 24 rows of characters from the ZX Spectrum character set or from a set provided within an application, from a palette of 15 shades: seven colours at two levels of brightness each, plus black; the image resolution is 256×192 with the same colour limitations. To conserve memory, colour is stored separate from the pixel bitmap in a low resolution, 32×24 grid overlay, corresponding to the character cells. In practice, this means that all pixels of an 8x8 character block share one foreground colour and one background colour.
Altwasser received a patent for this design. An "attribute" consists of a foreground and a background colour, a brightness level and a flashing "flag" which, when set, causes the two colours to swap at regular intervals; this scheme leads to what was dubbed colour clash or attribute clash, where a desired colour of a specific pixel could not be selected. This became a distinctive feature of the Spectrum, meaning programs games, had to be designed around this limitation. Other machines available around the same time, for example the Amstrad CPC or the Commodore 64, did not suffer from this limitation; the Commodore 64 used colour attributes in a similar way, but a special multicolour mode, hardware sprites and hardware scrolling were used to avoid attribute clash. Sound output is through a beeper on the machine itself, capable of producing one channel with 10 octaves. Software was available that could play two channel sound; the machine includes an expansion bus edge connector and 3.5 mm audio in/out ports for the connection of a cassette recorder for loading and saving programs and data.
The "ear" port has a higher output than the "mic" and is recommended for headphones, with "mic" for attaching to other audio devices as line in. It was manufactured in Scotland, in the now closed Timex factory; the machine's Sinclair BASIC interpreter is stored in ROM and was written by Steve Vickers on contract from Nine Tiles Ltd. The Spectrum's chiclet keyboard is marked with BASIC keywords. For example, pressing "G" when in programming mode would insert the BASIC command GO TO; the BASIC interpreter was developed from that used on the ZX81 and a ZX81 BASIC program can be typed into a Spectrum unmodified, but Spectrum BASIC included many extra features making it easier to use. The ZX Spectrum character set was expanded from that of the ZX81, which did not feature lower-case letters. Spectrum BASIC included extra keywords for the more advanced display and sound, supported multi-statement lines; the cassette interface was much more advanced and loading around five times faster than the ZX81, unlike the ZX81, the Spectrum could maintain the TV display during tape storage and retrieval operations.
As well as being able to save programs, the Spectrum could save the contents of arrays, the contents of the screen memory, the contents of any defined range of memory addresses. Rick Dickinson came up with a number of designs for the "ZX82" project before the final ZX Spectrum design. A number of the keyboard legends changed during the design phase including ARC becoming CIRCLE, FORE becoming INK and BACK becoming PAPER; the Spectrum reused a number of design elements of the ZX81: The ROM code for things such as floating point calculations and expression parsing were similar. The simple keyboard decoding and cassette interfaces were nearly identical; the central ULA integrated circuit was somewhat similar although it implemented the major enhancement over the ZX81: A hardware based television raster generator that indirectly gave the new machine four times as much processing power as the ZX81 due to the Z80 now being released from this video generation task. A bug in the ULA as designed