Central processing unit
A central processing unit called a central processor or main processor, is the electronic circuitry within a computer that carries out the instructions of a computer program by performing the basic arithmetic, logic and input/output operations specified by the instructions. The computer industry has used the term "central processing unit" at least since the early 1960s. Traditionally, the term "CPU" refers to a processor, more to its processing unit and control unit, distinguishing these core elements of a computer from external components such as main memory and I/O circuitry; the form and implementation of CPUs have changed over the course of their history, but their fundamental operation remains unchanged. Principal components of a CPU include the arithmetic logic unit that performs arithmetic and logic operations, processor registers that supply operands to the ALU and store the results of ALU operations and a control unit that orchestrates the fetching and execution of instructions by directing the coordinated operations of the ALU, registers and other components.
Most modern CPUs are microprocessors, meaning they are contained on a single integrated circuit chip. An IC that contains a CPU may contain memory, peripheral interfaces, other components of a computer; some computers employ a multi-core processor, a single chip containing two or more CPUs called "cores". Array processors or vector processors have multiple processors that operate in parallel, with no unit considered central. There exists the concept of virtual CPUs which are an abstraction of dynamical aggregated computational resources. Early computers such as the ENIAC had to be physically rewired to perform different tasks, which caused these machines to be called "fixed-program computers". Since the term "CPU" is defined as a device for software execution, the earliest devices that could rightly be called CPUs came with the advent of the stored-program computer; the idea of a stored-program computer had been present in the design of J. Presper Eckert and John William Mauchly's ENIAC, but was omitted so that it could be finished sooner.
On June 30, 1945, before ENIAC was made, mathematician John von Neumann distributed the paper entitled First Draft of a Report on the EDVAC. It was the outline of a stored-program computer that would be completed in August 1949. EDVAC was designed to perform a certain number of instructions of various types; the programs written for EDVAC were to be stored in high-speed computer memory rather than specified by the physical wiring of the computer. This overcame a severe limitation of ENIAC, the considerable time and effort required to reconfigure the computer to perform a new task. With von Neumann's design, the program that EDVAC ran could be changed by changing the contents of the memory. EDVAC, was not the first stored-program computer. Early CPUs were custom designs used as part of a sometimes distinctive computer. However, this method of designing custom CPUs for a particular application has given way to the development of multi-purpose processors produced in large quantities; this standardization began in the era of discrete transistor mainframes and minicomputers and has accelerated with the popularization of the integrated circuit.
The IC has allowed complex CPUs to be designed and manufactured to tolerances on the order of nanometers. Both the miniaturization and standardization of CPUs have increased the presence of digital devices in modern life far beyond the limited application of dedicated computing machines. Modern microprocessors appear in electronic devices ranging from automobiles to cellphones, sometimes in toys. While von Neumann is most credited with the design of the stored-program computer because of his design of EDVAC, the design became known as the von Neumann architecture, others before him, such as Konrad Zuse, had suggested and implemented similar ideas; the so-called Harvard architecture of the Harvard Mark I, completed before EDVAC used a stored-program design using punched paper tape rather than electronic memory. The key difference between the von Neumann and Harvard architectures is that the latter separates the storage and treatment of CPU instructions and data, while the former uses the same memory space for both.
Most modern CPUs are von Neumann in design, but CPUs with the Harvard architecture are seen as well in embedded applications. Relays and vacuum tubes were used as switching elements; the overall speed of a system is dependent on the speed of the switches. Tube computers like EDVAC tended to average eight hours between failures, whereas relay computers like the Harvard Mark I failed rarely. In the end, tube-based CPUs became dominant because the significant speed advantages afforded outweighed the reliability problems. Most of these early synchronous CPUs ran at low clock rates compared to modern microelectronic designs. Clock signal frequencies ranging from 100 kHz to 4 MHz were common at this time, limited by the speed of the switching de
The Information Age is a historic period in the 21st century characterized by the rapid shift from traditional industry that the Industrial Revolution brought through industrialization, to an economy based on information technology. The onset of the Information Age can be associated with William Shockley, Walter Houser Brattain and John Bardeen, the inventors and engineers behind the first transistors, revolutionising modern technologies. With the Digital Revolution, just as the Industrial Revolution marked the onset of the Industrial Age; the definition of what "digital" means continues to change over time as new technologies, user devices, methods of interaction with other humans and devices enter the domain of research and market launch. During the Information Age, digital industry shapes a knowledge-based society surrounded by a high-tech global economy that exerts influence on how the manufacturing and service sectors operate in an efficient and convenient way. In a commercialized society, the information industry can allow individuals to explore their personalized needs, therefore simplifying the procedure of making decisions for transactions and lowering costs both for producers and for buyers.
This is accepted overwhelmingly by participants throughout the entire economic activities for efficacy purposes, new economic incentives would be indigenously encouraged, such as the knowledge economy. The Information Age formed by capitalizing on computer microminiaturization advances; this evolution of technology in daily life and social organization has led to the modernization of information and communication processes becoming the driving force of social evolution. Library expansion was calculated in 1945 by Fremont Rider to double in capacity every 16 years if sufficient space were made available, he advocated replacing bulky, decaying printed works with miniaturized microform analog photographs, which could be duplicated on-demand for library patrons or other institutions. He did not foresee the digital technology that would follow decades to replace analog microform with digital imaging and transmission media. Automated lossless digital technologies allowed vast increases in the rapidity of information growth.
Moore's law, formulated around 1965, calculated that the number of transistors in a dense integrated circuit doubles every two years. The proliferation of the smaller and less expensive personal computers and improvements in computing power by the early 1980s resulted in sudden access to and the ability to share and store information for increasing numbers of workers. Connectivity between computers within companies led to the ability of workers at different levels to access greater amounts of information; the world's technological capacity to store information grew from 2.6 exabytes in 1986 to 15.8 in 1993, over 54.5 in 2000, to 295 exabytes in 2007. This is the informational equivalent to less than one 730-MB CD-ROM per person in 1986 4 CD-ROM per person of 1993, 12 CD-ROM per person in the year 2000, 61 CD-ROM per person in 2007, it is estimated that the world's capacity to store information has reached 5 zettabytes in 2014. This is the informational equivalent of 4,500 stacks of printed books from the earth to the sun.
The world's technological capacity to receive information through one-way broadcast networks was 432 exabytes of information in 1986, 715 exabytes in 1993, 1.2 zettabytes in 2000, 1.9 zettabytes in 2007. The world's effective capacity to exchange information through two-way telecommunication networks was 281 petabytes of information in 1986, 471 petabytes in 1993, 2.2 exabytes in 2000, 65 exabytes in 2007. In the 1990s, the spread of the Internet caused a sudden leap in access to and ability to share information in businesses and homes globally. Technology was developing so that a computer costing $3000 in 1997 would cost $2000 two years and $1000 the following year; the world's technological capacity to compute information with humanly guided general-purpose computers grew from 3.0 × 108 MIPS in 1986, to 4.4 × 109 MIPS in 1993, 2.9 × 1011 MIPS in 2000 to 6.4 × 1012 MIPS in 2007. An article in the recognized Journal Trends in Ecology and Evolution reports that by now digital technology "has vastly exceeded the cognitive capacity of any single human being and has done so a decade earlier than predicted.
In terms of capacity, there are two measures of importance: the number of operations a system can perform and the amount of information that can be stored. The number of synaptic operations per second in a human brain has been estimated to lie between 10^15 and 10^17. While this number is impressive in 2007 humanity's general-purpose computers were capable of performing well over 10^18 instructions per second. Estimates suggest. On a per capita basis, this is matched by current digital storage". Information and Communication Technology—computers, computerized machinery, fiber optics, communication satellites and other ICT tools—became a significant part of the economy. Microcomputers were developed and many businesses and industries were changed by ICT. Nicholas Negroponte captured the essence of these changes in his 1995 book, Being Digital
International maritime signal flags
International maritime signal flags are various flags used to communicate with ships. The principal system of flags and associated codes is the International Code of Signals. Various navies have flag systems with additional flags and codes, other flags are used in special uses, or have historical significance. There are various methods by which the flags can be used as signals: A series of flags can spell out a message, each flag representing a letter. Individual flags have standard meanings. One or more flags form a code word whose meaning can be looked up in a code book held by both parties. An example is the Popham numeric code used at the Battle of Trafalgar. In yacht racing and dinghy racing, flags have other meanings. NATO uses the same flags, with a few unique to warships, alone or in short sets to communicate various unclassified messages; the NATO usage differs from the international meanings, therefore warships will fly the Code/answer flag above the signal to indicate it should be read using the international meaning.
During the Allied occupations of Axis countries after World War II, use and display of those nations' national flags was banned. In order to comply with the international legal requirement that a ship identify its registry by displaying the appropriate national ensign, swallow-tailed versions of the C, D, E signal flags were designated as provisional German and Japanese civil ensigns. Being swallowtails, they are referred to as the "C-pennant", "D-pennant", "E-pennant". Notes Substitute or repeater flags allow messages with duplicate characters to be signaled without the need for multiple sets of flags; the four NATO substitute flags are as follows: The International Code of Signals includes only the first three of these substitute flags. To illustrate their use, here are some messages and the way they would be encoded: "How Ships Talk With Flags", October 1944, Popular Science John Savard's flag page. Collection of different flag systems. Freeware to aid memorizing the flags La flag-alfabeto - signal flags used for the Esperanto language - the flags for the Esperanto letters with diacritical marks have the lighter color in the normal flag replaced with light green, not used in any normal flag
Digital photography uses cameras containing arrays of electronic photodetectors to capture images focused by a lens, as opposed to an exposure on photographic film. The captured images are digitized and stored as a computer file ready for further digital processing, digital publishing or printing; until the advent of such technology, photographs were made by exposing light sensitive photographic film and paper, processed in liquid chemical solutions to develop and stabilize the image. Digital photographs are created by computer-based photoelectric and mechanical techniques, without wet bath chemical processing; the first consumer digital cameras were marketed in the late 1990s. Professionals gravitated to digital and were won over when their professional work required using digital files to fulfill the demands of employers and/or clients, for faster turn-around than conventional methods would allow. Starting around 2007, digital cameras were incorporated in cell phones and in the following years, cell phone cameras became widespread due to their connectivity to social media websites and email.
Since 2010, the digital point-and-shoot and DSLR formats have seen competition from the mirrorless digital camera format, which provides better image quality than the point-and-shoot or cell phone formats but comes in a smaller size and shape than the typical DSLR. Many mirrorless cameras accept interchangeable lenses and have advanced features through an electronic viewfinder, which replaces the through-the-lens finder image of the SLR format. While digital photography has only recently become mainstream, the late 20th century saw many small developments leading to its creation; the first image of Mars was taken as the Mariner 4 flew by it on July 15, 1965, with a camera system designed by NASA/JPL. While not what we define as a digital camera, it used a comparable process, it used a video camera tube, followed by a digitizer, rather than a mosaic of solid state sensor elements. This produced a digital image, stored on tape for slow transmission back to Earth; the real history of digital photography as we know.
In 1951, the first digital signals were saved to magnetic tape via the first video tape recorder. Six years in 1957, the first digital image was produced through a computer by Russell Kirsch, it was an image of his son. In the late 1960s, Willard S. Boyle and George E. Smith, two physicists with Bell Labs, Inc. invented the charge-coupled device, a semiconductor circuit used in the first digital video cameras for television broadcasting. Their invention was recognized by a Nobel Prize in Physics in 2009; the first published color digital photograph was produced in 1972 by Michael Francis Tompsett using CCD sensor technology and was featured on the cover of Electronics Magazine. It was a picture of Margaret Thompsett; the Cromemco Cyclops, a digital camera developed as a commercial product and interfaced to a microcomputer, was featured in the February 1975 issue of Popular Electronics magazine. It used metal-oxide semiconductor technology for its image sensor; the first self-contained digital camera was created in 1975 by Steven Sasson of Eastman Kodak.
Sasson's camera used CCD image sensor chips developed by Fairchild Semiconductor in 1973. The camera weighed 8 pounds, recorded black and white images to a cassette tape, had a resolution of 0.01 megapixels, took 23 seconds to capture its first image in December 1975. The prototype camera was a technical exercise. While it was not until 1981 that the first consumer camera was produced by Sony, Inc. the groundwork for digital imaging and photography had been laid. The first commercially available digital camera was the 1990 Dycam Model 1, it used a CCD image sensor, stored pictures digitally, connected directly to a computer for downloading images. Offered to professional photographers for a hefty price, by the mid-to-late 1990s, due to technology advancements, digital cameras were available to the general public; the advent of digital photography gave way to cultural changes in the field of photography. Unlike with traditional photography, dark rooms and hazardous chemicals were no longer required for post-production of an image - images could now be processed and enhanced from behind a computer screen in one's own home.
This allowed for photographers to be more creative with their editing techniques. As the field became more popular, types of digital photography and photographers diversified. Digital photography took photography itself from a small somewhat elite circle, to one that encompassed many people; the camera phone helped popularize digital photography, along with the internet and social media. The first cell phones with built-in digital cameras were produced in 2000 by Samsung. Small and easy to use, camera phones have made digital photography ubiquitous in the daily life of the general public. According to research from KeyPoint Intelligence/InfoTrends, an estimated 400 billion digital photos were taken globally in 2011 and this will rise to 1.2 trillion photos in 2017. An estimated 85 percent of the photos taken in 2017 will be done with the smartphone rather than a traditional digital camera. Image sensors read the intensity of light, digital memory devices store the digital image information as RGB color space or as raw data.
The two main types of sensors are charge-coupled devices, in which the photocharge is shifted to a central charge-to-voltage converter, CMOS or active pixel sensors. Except for some linear array type of cameras at the highest-end and simple
Home computers were a class of microcomputers that entered the market in 1977, that started with what Byte Magazine called the "trinity of 1977", which became common during the 1980s. They were marketed to consumers as affordable and accessible computers that, for the first time, were intended for the use of a single nontechnical user; these computers were a distinct market segment that cost much less than business, scientific or engineering-oriented computers of the time such as the IBM PC, were less powerful in terms of memory and expandability. However, a home computer had better graphics and sound than contemporary business computers, their most common uses were playing video games, but they were regularly used for word processing, doing homework, programming. Home computers were not electronic kits. There were, commercial kits like the Sinclair ZX80 which were both home and home-built computers since the purchaser could assemble the unit from a kit. Advertisements in the popular press for early home computers were rife with possibilities for their practical use in the home, from cataloging recipes to personal finance to home automation, but these were realized in practice.
For example, using a typical 1980s home computer as a home automation appliance would require the computer to be kept powered on at all times and dedicated to this task. Personal finance and database use required tedious data entry. By contrast, advertisements in the specialty computer press simply listed specifications. If no packaged software was available for a particular application, the home computer user could program one—provided they had invested the requisite hours to learn computer programming, as well as the idiosyncrasies of their system. Since most systems shipped with the BASIC programming language included on the system ROM, it was easy for users to get started creating their own simple applications. Many users found programming to be a fun and rewarding experience, an excellent introduction to the world of digital technology; the line between'business' and'home' computer market segments blurred or vanished once IBM PC compatibles became used in the home, since now both categories of computers use the same processor architectures, operating systems, applications.
The only difference may be the sales outlet through which they are purchased. Another change from the home computer era is that the once-common endeavour of writing one's own software programs has vanished from home computer use; as early as 1965, some experimental projects such as Jim Sutherland's ECHO IV explored the possible utility of a computer in the home. In 1969, the Honeywell Kitchen Computer was marketed as a luxury gift item, would have inaugurated the era of home computing, but none were sold. Computers became affordable for the general public in the 1970s due to the mass production of the microprocessor starting in 1971. Early microcomputers such as the Altair 8800 had front-mounted switches and diagnostic lights to control and indicate internal system status, were sold in kit form to hobbyists; these kits would contain an empty printed circuit board which the buyer would fill with the integrated circuits, other individual electronic components and connectors, hand-solder all the connections.
While two early home computers could be bought either in kit form or assembled, most home computers were only sold pre-assembled. They were enclosed in plastic or metal cases similar in appearance to typewriter or hi-fi equipment enclosures, which were more familiar and attractive to consumers than the industrial metal card-cage enclosures used by the Altair and similar computers; the keyboard - a feature lacking on the Altair - was built into the same case as the motherboard. Ports for plug-in peripheral devices such as a video display, cassette tape recorders and disk drives were either built-in or available on expansion cards. Although the Apple II series had internal expansion slots, most other home computer models' expansion arrangements were through externally accessible'expansion ports' that served as a place to plug in cartridge-based games; the manufacturer would sell peripheral devices designed to be compatible with their computers as extra cost accessories. Peripherals and software were not interchangeable between different brands of home computer, or between successive models of the same brand.
To save the cost of a dedicated monitor, the home computer would connect through an RF modulator to the family TV set, which served as both video display and sound system. By 1982, an estimated 621,000 home computers were in American households, at an average sales price of US$530. After the success of the Radio Shack TRS-80, the Commodore PET and the Apple II in 1977 every manufacturer of consumer electronics rushed to introduce a home computer. Large numbers of new machines of all types began to appear during the early 1980s. Mattel, Texas Instruments and Timex, none of which had any previous connection to the computer industry, all had short-lived home computer lines in the early 1980s; some home computers were more successful – the BBC Micro, Sinclair ZX Spectrum, Atari 800XL and Commodore 64, sold many units over several years and attracted third-party software development. Universally, home computers had a BASIC interpreter combined with a line editor in permanent read-only memory which one could use to type in BASIC programs and execute them
The smoke signal is one of the oldest forms of long-distance communication. It is a form of visual communication used over long distance. In general smoke signals are used to transmit news, signal danger, or gather people to a common area. In ancient China, soldiers stationed along the Great Wall would alert each other of impending enemy attack by signaling from tower to tower. In this way, they were able to transmit a message as far away as 750 kilometres in just a few hours. Misuse of the smoke signal is known to have contributed to the fall of the Western Zhou Dynasty in the 8th century BCE. King You of Zhou had a habit of fooling his warlords with false warning beacons in order to amuse Bao Si, his concubine. Polybius, a Greek historian, devised a more complex system of alphabetical smoke signals around 150 BCE, which converted Greek alphabetic characters into numeric characters, it enabled messages to be signaled by holding sets of torches in pairs. This idea, known as the "Polybius square" lends itself to cryptography and steganography.
This cryptographic concept has been used with Japanese Hiragana and the Germans in the years of the First World War. The North American indigenous peoples communicated via smoke signal; each tribe had understanding. A signaler started a fire on an elevation using damp grass, which would cause a column of smoke to rise; the grass would be taken off as it dried and another bundle would be placed on the fire. Reputedly the location of the smoke along the incline conveyed a meaning. If it came from halfway up the hill, this would signify all was well, but from the top of the hill it would signify danger. Smoke signals remain in use today. In Rome, the College of Cardinals uses smoke signals to indicate the selection of a new Pope during a papal conclave. Eligible cardinals conduct a secret ballot; the ballots are burned after each vote. Black smoke indicates a failed ballot. Colored smoke grenades are used by military forces to mark positions during calls for artillery or air support. Smoke signals may refer to smoke-producing devices used to send distress signals.
Lewis and Clark's journals cite several occasions when they adopted the Native American method of setting the plains on fire to communicate the presence of their party or their desire to meet with local tribes. Yámanas of South America used fire to send messages by smoke signals, for instance if a whale drifted ashore; the large amount of meat required notification of many people. They might have used smoke signals on other occasions, thus it is possible that Magellan saw such fires but he may have seen the smoke or lights of natural phenomena; the Cape Town Noon Gun the smoke its firing generates, was used to set marine chronometers in Table Bay. Aboriginal Australians throughout Australia would send up smoke signals for various purposes. Sometimes to notify others of their presence when entering lands which were not their own. Sometimes used to describe visiting whites, smoke signals were the fastest way. Smoke signals were sometimes to notify of incursions by hostile tribes, or to arrange meetings between hunting parties of the same tribe.
This signal could be from a fixed lookout on a ridge of from a mobile band of tribesman. "Putting up a smoke" would result in nearby individuals or groups replying with their own signals. To carry information, the colour of the smoke was varied, sometimes black, white or blue depending on whether the material being burnt was wet grass, dry grass, reeds or other, the shape of the smoke could be a column, ball or smoke ring; this message could include the names of individual tribesmen. Like other means of communication, signals could be misinterpreted. In one recorded instance, a smoke signal reply translated as "we are coming" was misinterpreted as joining a war party for protection of the tribe when it was hunting parties coming together after a successful hunt. Modern avionics has made skywriting possible. Gusinde, Martin. Nordwind—Südwind. Mythen und Märchen der Feuerlandindianer. Kassel: E. Röth. Itsz, Rudolf. "A kihunyt tüzek földje". Napköve. Néprajzi elbeszélések. Budapest: Móra Könyvkiadó. Pp. 93–112.
Translation of the original: Итс, Р.Ф.. Камень солнца. Ленинград: Detskaya Literatura. Title means: “Stone of sun”. Myers, Fred. Pintupi Country, Pintupi Self. USA: Smithsonian Institution