1.
Communications protocol
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These are the rules or standard that defines the syntax, semantics and synchronization of communication and possible error recovery methods. Protocols may be implemented by hardware, software, or a combination of both, Communicating systems use well-defined formats for exchanging various messages. Each message has a meaning intended to elicit a response from a range of possible responses pre-determined for that particular situation. The specified behavior is independent of how it is to be implemented. Communications protocols have to be agreed upon by the parties involved, to reach agreement, a protocol may be developed into a technical standard. Multiple protocols often describe different aspects of a single communication, a group of protocols designed to work together are known as a protocol suite, when implemented in software they are a protocol stack. Most recent protocols are assigned by the IETF for Internet communication, the ITU-T handles telecommunications protocols and formats for the PSTN. As the PSTN and Internet converge, the two sets of standards are also being driven towards convergence, the nature of a communication, the actual data exchanged and any state-dependent behaviors, is defined by these specifications. In digital computing systems, the rules can be expressed by algorithms, expressing the algorithms in a portable programming language makes the protocol software operating-system independent. Operating systems usually contain a set of cooperating processes that manipulate shared data to communicate each other. This communication is governed by protocols, which can be embedded in the process code itself. In contrast, because there is no memory, communicating systems have to communicate with each other using a shared transmission medium. Transmission is not necessarily reliable, and individual systems may use different hardware or operating systems, to implement a networking protocol, the protocol software modules are interfaced with a framework implemented on the machines operating system. This framework implements the functionality of the operating system. The best known frameworks are the TCP/IP model and the OSI model and this gave rise to the concept of layered protocols which nowadays forms the basis of protocol design. Systems typically do not use a protocol to handle a transmission. Instead they use a set of cooperating protocols, sometimes called a family or protocol suite. Some of the best known protocol suites are TCP/IP, IPX/SPX, X.25, AX.25, the protocols can be arranged based on functionality in groups, for instance there is a group of transport protocols
2.
Computer file
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A computer file is a computer resource for recording data discretely in a computer storage device. Just as words can be written to paper, so can information be written to a computer file, there are different types of computer files, designed for different purposes. A file may be designed to store a picture, a message, a video. Some types of files can store different several types of information at once, by using computer programs, a person can open, read, change, and close a computer file. Computer files may be reopened, modified, and copied a number of times. Typically, computer files are organised in a system, which keeps track of where the files are. The word file derives from the Latin filum, such a file now exists in a memory tube developed at RCA Laboratories. Electronically it retains figures fed into calculating machines, holds them in storage while it memorizes new ones - speeds intelligent solutions through mazes of mathematics, in 1952, file denoted, inter alia, information stored on punched cards. In early use, the hardware, rather than the contents stored on it, was denominated a file. For example, the IBM350 disk drives were denominated disk files, although the contemporary register file demonstrates the early concept of files, its use has greatly decreased. On most modern operating systems, files are organized into one-dimensional arrays of bytes, for example, the bytes of a plain text file are associated with either ASCII or UTF-8 characters, while the bytes of image, video, and audio files are interpreted otherwise. Most file types also allocate a few bytes for metadata, which allows a file to some basic information about itself. Some file systems can store arbitrary file-specific data outside of the file format, on other file systems this can be done via sidecar files or software-specific databases. All those methods, however, are susceptible to loss of metadata than are container. At any instant in time, a file might have a size, normally expressed as number of bytes, in most modern operating systems the size can be any non-negative whole number of bytes up to a system limit. Many older operating systems kept track only of the number of blocks or tracks occupied by a file on a storage device. In such systems, software employed other methods to track the exact byte count, the general definition of a file does not require that its size have any real meaning, however, unless the data within the file happens to correspond to data within a pool of persistent storage. A special case is a zero byte file, these files can be newly created files that have not yet had any data written to them, or may serve as some kind of flag in the file system, or are accidents
3.
Terminal emulator
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A terminal emulator, terminal application, term, or tty for short, is a program that emulates a video terminal within some other display architecture. Though typically synonymous with a shell or text terminal, the terminal covers all remote terminals. A terminal emulator inside a graphical interface is often called a terminal window. A terminal window allows the access to a text terminal and all its applications such as command-line interfaces. These may be running either on the machine or on a different one via telnet, ssh. On Unix-like operating systems, it is common to have one or more terminal windows connected to the local machine, terminals usually support a set of escape sequences for controlling color, cursor position, etc. Examples include the family of terminal control sequence standards known as ECMA-48, Terminal emulators may implement a local echo function, which may erroneously be named half-duplex, or still slightly incorrectly echoplex. Terminal emulators may implement local editing, also known as line-at-a-time mode and this is also mistakenly referred to as half-duplex. In this mode, the terminal emulator only sends complete lines of input to the host system, the user enters and edits a line, but it is held locally within the terminal emulator as it is being edited. It is not transmitted until the user signals its completion, usually with the ↵ Enter key on the keyboard or a button of some sort in the user interface. At that point the line is transmitted. Line-at-a-time mode implies local echo, since otherwise the user will not be able to see the line as it is being edited and constructed, however, line-at-a-time mode is independent of echo mode and does not require local echo. When entering a password, for example, line-at-a-time entry with local editing is possible, the complexities of line-at-a-time mode are exemplified by the line-at-a-time mode option in the telnet protocol. In asynchronous terminals data can flow in any direction at any time, in synchronous terminals a protocol controls who may send data when. IBM 3270-based terminals used with IBM mainframe computers are an example of synchronous terminals and they operate in an essentially screen-at-a-time mode. Users can make changes to a page, before submitting the updated screen to the remote machine as a single action. Other examples of synchronous terminals include the IBM5250, ICL7561, Honeywell Bull VIP7800, additionally, programs have been developed to emulate other terminal emulators such as xterm and assorted console terminals. Finally, some emulators simply refer to a standard, such as ANSI, such programs are available on many platforms ranging from DOS and Unix to Windows and macOS to embedded operating systems found in cellphones and industrial hardware
4.
Computer hardware
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Computer hardware is the collection of physical components that constitute a computer system. By contrast, software is instructions that can be stored and run by hardware, hardware is directed by the software to execute any command or instruction. A combination of hardware and software forms a usable computing system, the template for all modern computers is the Von Neumann architecture, detailed in a 1945 paper by Hungarian mathematician John von Neumann. The meaning of the term has evolved to mean a stored-program computer in which an instruction fetch and this is referred to as the Von Neumann bottleneck and often limits the performance of the system. For the third year, U. S. business-to-business channel sales increased. The impressive growth was the fastest sales increase since the end of the recession, sales growth accelerated in the second half of the year peaking in fourth quarter with a 6.9 percent increase over the fourth quarter of 2012. There are a number of different types of system in use today. The personal computer, also known as the PC, is one of the most common types of computer due to its versatility, laptops are generally very similar, although they may use lower-power or reduced size components, thus lower performance. The computer case is a plastic or metal enclosure that houses most of the components, a case can be either big or small, but the form factor of motherboard for which it is designed matters more. A power supply unit converts alternating current electric power to low-voltage DC power for the components of the computer. Laptops are capable of running from a battery, normally for a period of hours. The motherboard is the component of a computer. It is usually cooled by a heatsink and fan, or water-cooling system, most newer CPUs include an on-die Graphics Processing Unit. The clock speed of CPUs governs how fast it executes instructions, many modern computers have the option to overclock the CPU which enhances performance at the expense of greater thermal output and thus a need for improved cooling. The chipset, which includes the bridge, mediates communication between the CPU and the other components of the system, including main memory. Random-Access Memory, which stores the code and data that are being accessed by the CPU. For example, when a web browser is opened on the computer it takes up memory, RAM usually comes on DIMMs in the sizes 2GB, 4GB, and 8GB, but can be much larger. Read-Only Memory, which stores the BIOS that runs when the computer is powered on or otherwise begins execution, the BIOS includes boot firmware and power management firmware
5.
Operating system
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An operating system is system software that manages computer hardware and software resources and provides common services for computer programs. All computer programs, excluding firmware, require a system to function. Operating systems are found on many devices that contain a computer – from cellular phones, the dominant desktop operating system is Microsoft Windows with a market share of around 83. 3%. MacOS by Apple Inc. is in place, and the varieties of Linux is in third position. Linux distributions are dominant in the server and supercomputing sectors, other specialized classes of operating systems, such as embedded and real-time systems, exist for many applications. A single-tasking system can run one program at a time. Multi-tasking may be characterized in preemptive and co-operative types, in preemptive multitasking, the operating system slices the CPU time and dedicates a slot to each of the programs. Unix-like operating systems, e. g. Solaris, Linux, cooperative multitasking is achieved by relying on each process to provide time to the other processes in a defined manner. 16-bit versions of Microsoft Windows used cooperative multi-tasking, 32-bit versions of both Windows NT and Win9x, used preemptive multi-tasking. Single-user operating systems have no facilities to distinguish users, but may allow multiple programs to run in tandem, a distributed operating system manages a group of distinct computers and makes them appear to be a single computer. The development of networked computers that could be linked and communicate with each other gave rise to distributed computing, distributed computations are carried out on more than one machine. When computers in a work in cooperation, they form a distributed system. The technique is used both in virtualization and cloud computing management, and is common in large server warehouses, embedded operating systems are designed to be used in embedded computer systems. They are designed to operate on small machines like PDAs with less autonomy and they are able to operate with a limited number of resources. They are very compact and extremely efficient by design, Windows CE and Minix 3 are some examples of embedded operating systems. A real-time operating system is a system that guarantees to process events or data by a specific moment in time. A real-time operating system may be single- or multi-tasking, but when multitasking, early computers were built to perform a series of single tasks, like a calculator. Basic operating system features were developed in the 1950s, such as resident monitor functions that could run different programs in succession to speed up processing
6.
Text file
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A text file is a kind of computer file that is structured as a sequence of lines of electronic text. A text file exists within a file system. The end of a file is often denoted by placing one or more special characters. Such markers were required under the CP/M and MS-DOS operating systems, on modern operating systems such as Windows and Unix-like systems, text files do not contain any special EOF character. Text file refers to a type of container, while plain text refers to a type of content, Text files can contain plain text, but they are not limited to such. At a generic level of description, there are two kinds of files, text files and binary files. Because of their simplicity, text files are used for storage of information. They avoid some of the problems encountered with other formats, such as endianness, padding bytes. Further, when data corruption occurs in a file, it is often easier to recover. A disadvantage of text files is that usually have a low entropy. A simple text file needs no additional metadata to assist the reader in interpretation, and therefore may contain no data at all, the ASCII character set is the most common format for English-language text files, and is generally assumed to be the default file format in many situations. For accented and other characters, it is necessary to choose a character encoding. In many systems, this is chosen on the basis of the locale setting on the computer it is read on. Common character encodings include ISO 8859-1 for many European languages, because many encodings have only a limited repertoire of characters, they are often only usable to represent text in a limited subset of human languages. Unicode is an attempt to create a standard for representing all known languages. On most operating systems the name text file refers to file format that only plain text content with very little formatting. Such files can be viewed and edited on text terminals or in text editors. Text files usually have the MIME type text/plain, usually with additional information indicating an encoding, MS-DOS and Windows use a common text file format, with each line of text separated by a two-character combination, carriage return and line feed
7.
Binary file
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A binary file is a computer file that is not a text file. The term binary file is used as a term meaning non-text file. Binary files are usually thought of as being a sequence of bytes, binary files typically contain bytes that are intended to be interpreted as something other than text characters. Compiled computer programs are examples, indeed, compiled applications are sometimes referred to, particularly by programmers. But binary files can also mean that they contain images, sounds, compressed versions of files, etc. — in short. Some binary files contain headers, blocks of metadata used by a program to interpret the data in the file. The header often contains a signature or magic number which can identify the format, for example, a GIF file can contain multiple images, and headers are used to identify and describe each block of image data. The leading bytes of the header would contain text like GIF87a or GIF89a that can identify the binary as a GIF file, if a binary file does not contain any headers, it may be called a flat binary file. To send binary files through certain systems that do not allow all data values, encoding the data has the disadvantage of increasing the file size during the transfer, as well as requiring translation back into binary after receipt. See Binary-to-text encoding for more on this subject, a hex editor or viewer may be used to view file data as a sequence of hexadecimal values for corresponding bytes of a binary file. If a binary file is opened in an editor, each group of eight bits will typically be translated as a single character. Other type of viewers simply replace the characters with spaces revealing only the human-readable text. This type of view is useful for inspection of a binary file in order to find passwords in games, find hidden text in non-text files. It can even be used to inspect suspicious files for unwanted effects, for example, the user would see any URL/email to which the suspected software may attempt to connect in order to upload unapproved data. If the file is itself treated as an executable and run, standards are very important to binary files. For example, a binary file interpreted by the ASCII character set will result in text being displayed, a custom application can interpret the file differently, a byte may be a sound, or a pixel, or even an entire word. Binary itself is meaningless, until such time as an executed algorithm defines what should be done with each bit, byte, thus, just examining the binary and attempting to match it against known formats can lead to the wrong conclusion as to what it actually represents. This fact can be used in steganography, where an algorithm interprets a binary data file differently to reveal hidden content, without the algorithm, it is impossible to tell that hidden content exists
8.
RS-232
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In telecommunications, RS-232 is a standard for serial communication transmission of data. It formally defines the signals connecting between a DTE such as a terminal, and a DCE, such as a modem. The RS-232 standard is used in computer serial ports. The standard defines the characteristics and timing of signals, the meaning of signals. The current version of the standard is TIA-232-F Interface Between Data Terminal Equipment and Data Circuit-Terminating Equipment Employing Serial Binary Data Interchange, issued in 1997. An RS-232 serial port was once a feature of a personal computer, used for connections to modems, printers, mice, data storage, uninterruptible power supplies. However, RS-232 is hampered by low speed, large voltage swing. In modern personal computers, USB has displaced RS-232 from most of its peripheral interface roles, nevertheless, RS-232 devices are still used, especially in industrial machines, networking equipment, and scientific instruments. Interface mechanical characteristics, pluggable connectors and pin identification, functions of each circuit in the interface connector. Standard subsets of interface circuits for selected telecom applications, the standard does not define such elements as the character encoding, the framing of characters, transmission order of bits, or error detection protocols. The character format and transmission bit rate are set by the serial port hardware which may also contain circuits to convert the internal logic levels to RS-232 compatible signal levels. The standard does not define bit rates for transmission, except that it says it is intended for bit rates lower than 20,000 bits per second, RS-232 was first introduced in 1960 by the Electronic Industries Association as a Recommended Standard. The original DTEs were electromechanical teletypewriters, and the original DCEs were modems, when electronic terminals began to be used, they were often designed to be interchangeable with teletypewriters, and so supported RS-232. The C revision of the standard was issued in 1969 in part to accommodate the electrical characteristics of these devices, the resulting common problems were non-standard pin assignment of circuits on connectors, and incorrect or missing control signals. The lack of adherence to the standards produced a thriving industry of breakout boxes, patch boxes, test equipment, books, a common deviation from the standard was to drive the signals at a reduced voltage. Some manufacturers therefore built transmitters that supplied +5 V and −5 V, later personal computers started to make use of the standard so that they could connect to existing equipment. For many years, an RS-232-compatible port was a feature for serial communications, such as modem connections. It remained in use into the late 1990s
9.
Sliding window protocol
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A sliding window protocol is a feature of packet-based data transmission protocols. Sliding window protocols are used where reliable in-order delivery of packets is required, the problem with this is that there is no limit on the size of the sequence number that can be required. The term window on the transmitter side represents the boundary of the total number of packets yet to be acknowledged by the receiver. The receiver informs the transmitter in each acknowledgment packet the current maximum receiver buffer size, the TCP header uses a 16 bit field to report the receive window size to the sender. Therefore, the largest window that can be used is 216 =64 kilobytes, in slow-start mode, the transmitter starts with low packet count and increases the number of packets in each transmission after receiving acknowledgment packets from receiver. For every ack packet received, the window slides by one packet to one new packet. When the window threshold is reached, the transmitter sends one packet for one ack packet received. If the window limit is 10 packets then in slow start mode the transmitter may start transmitting one packet followed by two packets, followed by three packets and so on until 10 packets. But after reaching 10 packets, further transmissions are restricted to one packet transmitted for one ack packet received, in a simulation this appears as if the window is moving by one packet distance for every ack packet received. On the receiver side also the window moves one packet for every packet received, the sliding window method ensures that traffic congestion on the network is avoided. The window size may vary depending on network traffic. For the highest possible throughput, it is important that the transmitter is not forced to stop sending by the sliding window protocol earlier than one round-trip delay time. The limit on the amount of data that it can send before stopping to wait for an acknowledgment should be larger than the product of the communications link. If it is not, the protocol will limit the bandwidth of the link. In any communication protocol based on automatic repeat request for error control, if the transmitter does not receive an acknowledgment within a reasonable time, it re-sends the data. A transmitter that does not hear an acknowledgment cannot know if the receiver actually received the packet, if error detection reveals corruption, the packet will be ignored by the receiver and no acknowledgement will be sent. Similarly, the receiver is usually uncertain about whether its acknowledgements are being received and it may be that an acknowledgment was sent, but was lost or corrupted in the transmission medium. In this case, the receiver must acknowledge the retransmission to prevent the data being continually resent, the transmitter and receiver each have a current sequence numbernt and nr, respectively
10.
Columbia University
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Columbia University is a private Ivy League research university in Upper Manhattan, New York City. It was established in 1754 as Kings College by royal charter of George II of Great Britain, after the American Revolutionary War, Kings College briefly became a state entity, and was renamed Columbia College in 1784. Columbia is one of the fourteen founding members of the Association of American Universities and was the first school in the United States to grant the M. D. degree. The university also has global research outposts in Amman, Beijing, Istanbul, Paris, Mumbai, Rio de Janeiro, Santiago, Asunción, Columbia administers annually the Pulitzer Prize. Additionally,100 Nobel laureates have been affiliated with Columbia as students, researchers, faculty, Columbia is second only to Harvard University in the number of Nobel Prize-winning affiliates, with over 100 recipients of the award as of 2016. In 1746 an act was passed by the assembly of New York to raise funds for the foundation of a new college. Classes were initially held in July 1754 and were presided over by the colleges first president, Dr. Johnson was the only instructor of the colleges first class, which consisted of a mere eight students. Instruction was held in a new schoolhouse adjoining Trinity Church, located on what is now lower Broadway in Manhattan, in 1763, Dr. Johnson was succeeded in the presidency by Myles Cooper, a graduate of The Queens College, Oxford, and an ardent Tory. In the charged political climate of the American Revolution, his opponent in discussions at the college was an undergraduate of the class of 1777. The suspension continued through the occupation of New York City by British troops until their departure in 1783. The colleges library was looted and its sole building requisitioned for use as a hospital first by American. Loyalists were forced to abandon their Kings College in New York, the Loyalists, led by Bishop Charles Inglis fled to Windsor, Nova Scotia, where they founded Kings Collegiate School. After the Revolution, the college turned to the State of New York in order to restore its vitality, the Legislature agreed to assist the college, and on May 1,1784, it passed an Act for granting certain privileges to the College heretofore called Kings College. The Regents finally became aware of the colleges defective constitution in February 1787 and appointed a revision committee, in April of that same year, a new charter was adopted for the college, still in use today, granting power to a private board of 24 Trustees. On May 21,1787, William Samuel Johnson, the son of Dr. Samuel Johnson, was unanimously elected President of Columbia College, prior to serving at the university, Johnson had participated in the First Continental Congress and been chosen as a delegate to the Constitutional Convention. The colleges enrollment, structure, and academics stagnated for the majority of the 19th century, with many of the college presidents doing little to change the way that the college functioned. In 1857, the college moved from the Kings College campus at Park Place to a primarily Gothic Revival campus on 49th Street and Madison Avenue, during the last half of the 19th century, under the leadership of President F. A. P. Barnard, the institution assumed the shape of a modern university
11.
Statistical multiplexing
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Statistical multiplexing is a type of communication link sharing, very similar to dynamic bandwidth allocation. In statistical multiplexing, a channel is divided into an arbitrary number of variable bitrate digital channels or data streams. The link sharing is adapted to the traffic demands of the data streams that are transferred over each channel. This is an alternative to creating a fixed sharing of a link, such as in general time division multiplexing, when performed correctly, statistical multiplexing can provide a link utilization improvement, called the statistical multiplexing gain. Statistical multiplexing is facilitated through packet mode or packet-oriented communication, which among others is utilized in packet switched computer networks, each stream is divided into packets that normally are delivered asynchronously in a first-come first-served fashion. In alternative fashion, the packets may be delivered according to some scheduling discipline for fair queuing or differentiated and/or guaranteed quality of service, statistical multiplexing normally implies on-demand service rather than one that preallocates resources for each data stream. Statistical multiplexing schemes do not control user data transmissions, statistical multiplexing allows the bandwidth to be divided arbitrarily among a variable number of channels. Statistical multiplexing ensures that slots will not be wasted, the transmission capacity of the link will be shared by only those users who have packets. Static TDM and other circuit switching is carried out at the layer in the OSI model and TCP/IP model, while statistical multiplexing is carried out at the data link layer. In statistical multiplexing, each packet or frame contains a channel/data stream identification number, examples of statistical multiplexing are, The MPEG transport stream for digital TV transmission. Statistical multiplexing is used to allow several video, audio and data streams of different data rates to be transmitted over a bandwidth-limited channel, the channel number is denoted Program ID. The UDP and TCP protocols, where streams from several application processes are multiplexed together. The packets may have varying lengths, the port numbers constitute channel identification numbers. The X.25 and Frame relay packet-switching protocols, where the packets have varying lengths, and the channel number is denoted Virtual Connection Identifier. The international collection of X.25 providers, using the X.25 protocol suite was known as the Packet switched network in the 1980s. The Asynchronous Transfer Mode packet-switched protocol, where the packets have fixed length, the channel identification number consists of a Virtual Connection Identifier and a Virtual Path Identifier. The multiplexer allocates to each service the bandwidth required for its real-time needs so that services with complex scenes receive more bandwidth than services with complex ones. This bandwidth sharing technique produces the best video quality at the lowest possible aggregate bandwidth
12.
ASCII
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ASCII, abbreviated from American Standard Code for Information Interchange, is a character encoding standard. ASCII codes represent text in computers, telecommunications equipment, and other devices, most modern character-encoding schemes are based on ASCII, although they support many additional characters. ASCII was developed from telegraph code and its first commercial use was as a seven-bit teleprinter code promoted by Bell data services. Work on the ASCII standard began on October 6,1960, the first edition of the standard was published in 1963, underwent a major revision during 1967, and experienced its most recent update during 1986. Compared to earlier telegraph codes, the proposed Bell code and ASCII were both ordered for more convenient sorting of lists, and added features for other than teleprinters. Originally based on the English alphabet, ASCII encodes 128 specified characters into seven-bit integers as shown by the ASCII chart above. The characters encoded are numbers 0 to 9, lowercase letters a to z, uppercase letters A to Z, basic punctuation symbols, control codes that originated with Teletype machines, for example, lowercase j would become binary 1101010 and decimal 106. ASCII includes definitions for 128 characters,33 are non-printing control characters that affect how text and space are processed and 95 printable characters, of these, the IANA encourages use of the name US-ASCII for Internet uses of ASCII. The ASA became the United States of America Standards Institute and ultimately the American National Standards Institute, there was some debate at the time whether there should be more control characters rather than the lowercase alphabet. The X3.2.4 task group voted its approval for the change to ASCII at its May 1963 meeting, the X3 committee made other changes, including other new characters, renaming some control characters and moving or removing others. ASCII was subsequently updated as USAS X3. 4-1967, then USAS X3. 4-1968, ANSI X3. 4-1977 and they proposed a 9-track standard for magnetic tape, and attempted to deal with some punched card formats. The X3.2 subcommittee designed ASCII based on the earlier teleprinter encoding systems, like other character encodings, ASCII specifies a correspondence between digital bit patterns and character symbols. This allows digital devices to communicate each other and to process, store. Before ASCII was developed, the encodings in use included 26 alphabetic characters,10 numerical digits, ITA2 were in turn based on the 5-bit telegraph code Émile Baudot invented in 1870 and patented in 1874. The committee debated the possibility of a function, which would allow more than 64 codes to be represented by a six-bit code. In a shifted code, some character codes determine choices between options for the character codes. It allows compact encoding, but is reliable for data transmission. The standards committee decided against shifting, and so ASCII required at least a seven-bit code, the committee considered an eight-bit code, since eight bits would allow two four-bit patterns to efficiently encode two digits with binary-coded decimal
13.
Bootstrapping
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In general parlance, bootstrapping usually refers to a self-starting process that is supposed to proceed without external input. The term appears to have originated in the early 19th century United States, to mean an absurdly impossible action, an adynaton. Tall boots may have a tab, loop or handle at the top known as a bootstrap, the saying to pull oneself up by ones bootstraps was already in use during the 19th century as an example of an impossible task. In 1860 it appeared in a comment on philosophy of mind, Bootstrap as a metaphor, meaning to better oneself by ones own unaided efforts, was in use in 1922. This metaphor spawned additional metaphors for a series of self-sustaining processes that proceed without external help, booting is the process of starting a computer, specifically with regard to starting its software. The process involves a chain of stages, in which at each stage a smaller, simpler program loads and then executes the larger and it is in this sense that the computer pulls itself up by its bootstraps, i. e. it improves itself by its own efforts. Booting is a chain of events that starts with execution of hardware-based procedures, booting often involves processes such as performing self-tests, loading configuration settings, loading a BIOS, resident monitors, a hypervisor, an operating system, or utility software. The computer term bootstrap began as a metaphor in the 1950s, in computers, pressing a bootstrap button caused a hardwired program to read a bootstrap program from an input unit. The computer would then execute the program, which caused it to read more program instructions. It became a process that proceeded without external help from manually entered instructions. As a computing term, bootstrap has been used since at least 1953, bootstrapping can also refer to the development of successively more complex, faster programming environments. The simplest environment will be, perhaps, a basic text editor. Historically, bootstrapping refers to an early technique for computer program development on new hardware. The technique described in this paragraph has been replaced by the use of a cross executed by a pre-existing computer. A tiny assembler program was hand-coded for a new computer which converted a few instructions into binary or decimal code and this simple assembler program was then rewritten in its just-defined assembly language but with extensions that would enable the use of some additional mnemonics for more complex operation codes. This was how the early assembly program SOAP was developed, compilers, linkers, loaders, and utilities were then coded in assembly language, further continuing the bootstrapping process of developing complex software systems by using simpler software. The term was also championed by Doug Engelbart to refer to his belief that organizations could better evolve by improving the process they use for improvement and his SRI team that developed the NLS hypertext system applied this strategy by using the tool they had developed to improve the tool. Using an existing language to bootstrap a new language is one way to solve the chicken or the egg causality dilemma, during the installation of computer programs it is sometimes necessary to update the installer or package manager itself
14.
Type-in program
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Type-ins were often seen as useful for learning programming, allowing users to begin their programming efforts by porting a program written for one system for use on another. Here is an example of a type-in, Listing 1. 20 GOTO10 To use this type-in, a reader would take a copy of the program listing, such as from a magazine or book, sit down at a computer. Computers of this era automatically booted into a programming environment – even the commands to load, after typing the program in, the user would be able to run it and also to save it to disk or cassette for future use. Users were often cautioned to save the program before running it, as errors could result in a crash requiring a reboot, the simple program displayed above is a trivial example - many type-ins were fully functional games or application software, sometimes rivaling commercial packages. Type-ins were usually written in BASIC or a combination of a BASIC loader, in some cases, a special program for entering machine language numerically was provided. Programs with a language component sometimes included assembly language listings for users who had assemblers. The downside of type-ins was labor, the work required to enter a medium-sized type-in was on the order of hours. If the resulting program turned out not to be to the users taste, additionally, type-ins were error-prone, both for users and for the magazines. This was especially true of the language parts of BASIC programs. While a BASIC program would stop with an error at an incorrect statement. This made the entry of programs difficult. To counter the difficulty of keying a type-in, the MIKBUG machine code monitor for the Motorola 6800 of the late 1970s incorporated a checksum into its program listings. Later, some magazines developed checksum programs of their own, there were many different styles of checksum program, usually depending on the type of program being entered and on the complexity of the checksummer. Checksummers were proprietary and were printed in every issue of the magazine. The most basic distinction was whether the checksummer was run only once, the former type either read the typed-in computer code off a disk, or read it directly from memory. The checksum program would print a checksum for each line of code, the magazine would print the correct checksums adjacent to the listing, and the user would compare the two to catch errors. More advanced checksum programs were used interactively and they would take a line of code as it was entered and immediately produce a checksum which could be compared to the printed listing
15.
BASIC
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BASIC is a family of general-purpose, high-level programming languages whose design philosophy emphasizes ease of use. In 1964, John G. Kemeny and Thomas E. Kurtz designed the original BASIC language at Dartmouth College in the U. S. state of New Hampshire and they wanted to enable students in fields other than science and mathematics to use computers. At the time, nearly all use of computers required writing custom software, versions of BASIC became widespread on microcomputers in the mid-1970s and 1980s. Microcomputers usually shipped with BASIC, often in the machines firmware, having an easy-to-learn language on these early personal computers allowed small business owners, professionals, hobbyists, and consultants to develop custom software on computers they could afford. In the 2010s, BASIC remains popular in many computing dialects and in new languages influenced by BASIC, before the mid-1960s, the only computers were huge mainframe computers. Users submitted jobs on punched cards or similar media to specialist computer operators, the computer stored these, then used a batch processing system to run this queue of jobs one after another, allowing very high levels of utilization of these expensive machines. As the performance of computing hardware rose through the 1960s, multi-processing was developed and this allowed a mix of batch jobs to be run together, but the real revolution was the development of time-sharing. The original BASIC language was released on May 1,1964 by John G. Kemeny and Thomas E. Kurtz, the acronym BASIC comes from the name of an unpublished paper by Thomas Kurtz. BASIC was designed to allow students to write computer programs for the Dartmouth Time-Sharing System. It was intended specifically for technical users who did not have or want the mathematical background previously expected. Being able to use a computer to support teaching and research was quite novel at the time, the language was based on FORTRAN II, with some influences from ALGOL60 and with additions to make it suitable for timesharing. Wanting use of the language to become widespread, its designers made the available free of charge. They also made it available to schools in the Hanover area. In the following years, as dialects of BASIC appeared, Kemeny. A version was a part of the Pick operating system from 1973 onward. During this period a number of computer games were written in BASIC. A number of these were collected by DEC employee David H. Ahl and he later collected a number of these into book form,101 BASIC Computer Games, published in 1973. During the same period, Ahl was involved in the creation of a computer for education use
16.
Floppy disk
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Floppy disks are read and written by a floppy disk drive. Floppy disks, initially as 8-inch media and later in 5¼-inch and 3½-inch sizes, were a form of data storage and exchange from the mid-1970s into the mid-2000s. These formats are usually handled by older equipment and these disks and associated drives were produced and improved upon by IBM and other companies such as Memorex, Shugart Associates, and Burroughs Corporation. The term floppy disk appeared in print as early as 1970, in 1976, Shugart Associates introduced the first 5¼-inch FDD. By 1978 there were more than 10 manufacturers producing such FDDs, there were competing floppy disk formats, with hard- and soft-sector versions and encoding schemes such as FM, MFM and GCR. The 5¼-inch format displaced the 8-inch one for most applications, the most common capacity of the 5¼-inch format in DOS-based PCs was 360 kB and in 1984 IBM introduced the 1.2 MB dual-sided floppy disk along with its PC-AT model. IBM started using the 720 kB double-density 3½-inch microfloppy disk on its Convertible laptop computer in 1986 and these disk drives could be added to older PC models. In 1988 IBM introduced a drive for 2.88 MB DSED diskettes in its top-of-the-line PS/2 models, throughout the early 1980s, limitations of the 5¼-inch format became clear. Originally designed to be practical than the 8-inch format, it was itself too large, as the quality of recording media grew. A number of solutions were developed, with drives at 2-, 2½-, 3-, 3½-, the large market share of the 5¼-inch format made it difficult for these new formats to gain significant market share. A variant on the Sony design, introduced in 1982 by a number of manufacturers, was then rapidly adopted. By the end of the 1980s, 5¼-inch disks had been superseded by 3½-inch disks, by the mid-1990s, 5¼-inch drives had virtually disappeared, as the 3½-inch disk became the predominant floppy disk. Floppy disks became ubiquitous during the 1980s and 1990s in their use with computers to distribute software, transfer data. Before hard disks became affordable to the population, floppy disks were often used to store a computers operating system. Most home computers from that period have a primary OS and BASIC stored as ROM, by the early 1990s, the increasing software size meant large packages like Windows or Adobe Photoshop required a dozen disks or more. In 1996, there were a five billion standard floppy disks in use. Then, distribution of packages was gradually replaced by CD-ROMs, DVDs. External USB-based floppy disk drives are available, many modern systems provide firmware support for booting from such drives
17.
Null modem
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Null modem is a communication method to directly connect two DTEs using an RS-232 serial cable. The RS-232 standard is asymmetric as to the definitions of the two ends of the link, assuming that one end is a DTE and the other is a DCE. With a null modem connection the transmit and receive lines are crosslinked, depending on the purpose, sometimes also one or more handshake lines are crosslinked. Several wiring layouts are in use because the null modem connection is not covered by the RS-232 standard, originally, the RS-232 standard was developed and used for teleprinter machines which could communicate with each other over phone lines. Each teleprinter would be connected to its modem via an RS-232 connection. If a user wished to connect two teleprinters directly without modems then they would crosslink the connections, the term null modem may also refer to the cable or adapter itself as well as the connection method. Null modem cables were a method for transferring data between the early personal computers from the 1980s to the early 1990s. A null modem cable is a RS-232 serial cable where the transmit, in some cables there are also handshake lines crosslinked. In many situations a straight-through serial cable is used, together with a null modem adapter, the adapter contains the necessary crosslinks between the signals. As the RS-232 standard was adopted by other types of equipment, when an application required that two DTEs needed to communicate with each other, then a null modem was necessary. Null modems were commonly used for transfer between computers, or remote operation. Under the Microsoft Windows operating system, the cable connection can be used over a null modem connection. The later versions of MS-DOS were shipped with the InterLnk program, both pieces of software allow the mapping of a hard disk on one computer as a network drive on the other computer. No Ethernet hardware is required for this, on the Commodore Amiga system, a null modem connection was a common way of playing multiplayer games between two machines. The popularity and availability of information exchange systems such as Ethernet made the use of null modem cables less common. In modern systems, such a cable can still be useful for kernel development, since it allows the user to remotely debug a kernel with a minimum of device drivers. KGDB for Linux, ddb for BSD, and WinDbg or KD for Windows can be used to remotely debug systems, for example. This can also provide a serial console through which the in-kernel debugger can be dropped to in case of kernel panics, in case the local monitor
18.
Mainframe computer
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The term originally referred to the large cabinets called main frames that housed the central processing unit and main memory of early computers. Later, the term was used to distinguish high-end commercial machines from less powerful units, most large-scale computer system architectures were established in the 1960s, but continue to evolve. Their high stability and reliability enable these machines to run uninterrupted for decades, Mainframes are defined by high availability, one of the main reasons for their longevity, since they are typically used in applications where downtime would be costly or catastrophic. The term reliability, availability and serviceability is a characteristic of mainframe computers. Proper planning and implementation is required to exploit these features, and if improperly implemented, in the late 1950s, most mainframes had no explicitly interactive interface, but only accepted sets of punched cards, paper tape, or magnetic tape to transfer data and programs. In cases where interactive terminals were supported, these were used almost exclusively for applications rather than program development, typewriter and Teletype devices were also common control consoles for system operators through the 1970s, although ultimately supplanted by keyboard/display devices. By the early 1970s, many mainframes acquired interactive user interfaces and operated as timesharing computers, users gained access through specialized terminals or, later, from personal computers equipped with terminal emulation software. By the 1980s, many mainframes supported graphical terminals, and terminal emulation and this format of end-user computing reached mainstream obsolescence in the 1990s due to the advent of personal computers provided with GUIs. After 2000, most modern mainframes have partially or entirely phased out classic green screen terminal access for end-users in favour of Web-style user interfaces, the infrastructure requirements were drastically reduced during the mid-1990s, when CMOS mainframe designs replaced the older bipolar technology. IBM claimed that its newer mainframes could reduce data center energy costs for power and cooling, modern mainframes can run multiple different instances of operating systems at the same time. This technique of virtual machines allows applications to run as if they were on physically distinct computers, in this role, a single mainframe can replace higher-functioning hardware services available to conventional servers. While mainframes pioneered this capability, virtualization is now available on most families of computer systems, Mainframes can add or hot swap system capacity without disrupting system function, with specificity and granularity to a level of sophistication not usually available with most server solutions. Modern mainframes, notably the IBM zSeries, System z9 and System z10 servers, such a two-mainframe installation can support continuous business service, avoiding both planned and unplanned outages. In practice many customers use multiple mainframes linked either by Parallel Sysplex and shared DASD, or with shared, Mainframes are designed to handle very high volume input and output and emphasize throughput computing. Since the late-1950s, mainframe designs have included subsidiary hardware which manage the I/O devices and it is common in mainframe shops to deal with massive databases and files. Gigabyte to terabyte-size record files are not unusual, compared to a typical PC, mainframes commonly have hundreds to thousands of times as much data storage online, and can access it reasonably quickly. Other server families also offload I/O processing and emphasize throughput computing, Mainframes also have execution integrity characteristics for fault tolerant computing. This hardware-level feature, also found in HPs NonStop systems, is known as lock-stepping, not all applications absolutely need the assured integrity that these systems provide, but many do, such as financial transaction processing
19.
Microcomputer
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A microcomputer is a small, relatively inexpensive computer with a microprocessor as its central processing unit. It includes a microprocessor, memory, and minimal input/output circuitry mounted on a printed circuit board. Microcomputers became popular in the 1970s and 1980s with the advent of increasingly powerful microprocessors, the predecessors to these computers, mainframes and minicomputers, were comparatively much larger and more expensive. Many microcomputers are also personal computers, the abbreviation micro was common during the 1970s and 1980s, but has now fallen out of common usage. The term microcomputer came into use after the introduction of the minicomputer. Most notably, the replaced the many separate components that made up the minicomputers CPU with one integrated microprocessor chip. The first microcomputer was the Japanese Sord Computer Corporations SMP80/08, which was followed by the SMP80/x, the French developers of the Micral N filed their patents with the term Micro-ordinateur, a literal equivalent of Microcomputer, to designate a solid state machine designed with a microprocessor. Use of audio cassettes for data storage replaced manual re-entry of a program every time the device was powered on. Large cheap arrays of silicon logic gates in the form of memory and EPROMs allowed utility programs. This replaced the slow, complex, and expensive teletypewriter that was common as an interface to minicomputers. All these improvements in cost and usability resulted in an explosion in their popularity during the late 1970s, a large number of computer makers packaged microcomputers for use in small business applications. This allowed businesses unable to afford leasing of a minicomputer or time-sharing service the opportunity to automate business functions, without hiring a full-time staff to operate the computers. A representative system of this era would have used an S100 bus, an 8-bit processor such as an Intel 8080 or Zilog Z80, the increasing availability and power of desktop computers for personal use attracted the attention of more software developers. In time, and as the industry matured, the market for personal computers standardized around IBM PC compatibles running DOS, everyday use of the expression microcomputer has declined significantly from the mid-1980s and has declined in commonplace usage since 2000. The term is most commonly associated with the first wave of all-in-one 8-bit home computers, although, or perhaps because, an increasingly diverse range of modern microprocessor-based devices fit the definition of microcomputer, they are no longer referred to as such in everyday speech. IBM first promoted the personal computer to differentiate themselves from other microcomputers, often called home computers. However, following its release, the IBM PC itself was widely imitated, the component parts were commonly available to producers and the BIOS was reverse engineered through cleanroom design techniques. IBM PC compatible clones became commonplace, and the personal computer
20.
IBM
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International Business Machines Corporation is an American multinational technology company headquartered in Armonk, New York, United States, with operations in over 170 countries. The company originated in 1911 as the Computing-Tabulating-Recording Company and was renamed International Business Machines in 1924, IBM manufactures and markets computer hardware, middleware and software, and offers hosting and consulting services in areas ranging from mainframe computers to nanotechnology. IBM is also a research organization, holding the record for most patents generated by a business for 24 consecutive years. IBM has continually shifted its business mix by exiting commoditizing markets and focusing on higher-value, also in 2014, IBM announced that it would go fabless, continuing to design semiconductors, but offloading manufacturing to GlobalFoundries. Nicknamed Big Blue, IBM is one of 30 companies included in the Dow Jones Industrial Average and one of the worlds largest employers, with nearly 380,000 employees. Known as IBMers, IBM employees have been awarded five Nobel Prizes, six Turing Awards, ten National Medals of Technology, in the 1880s, technologies emerged that would ultimately form the core of what would become International Business Machines. On June 16,1911, their four companies were amalgamated in New York State by Charles Ranlett Flint forming a fifth company, the Computing-Tabulating-Recording Company based in Endicott, New York. The five companies had 1,300 employees and offices and plants in Endicott and Binghamton, New York, Dayton, Ohio, Detroit, Michigan, Washington, D. C. and Toronto. They manufactured machinery for sale and lease, ranging from commercial scales and industrial time recorders, meat and cheese slicers, to tabulators and punched cards. Thomas J. Watson, Sr. fired from the National Cash Register Company by John Henry Patterson, called on Flint and, Watson joined CTR as General Manager then,11 months later, was made President when court cases relating to his time at NCR were resolved. Having learned Pattersons pioneering business practices, Watson proceeded to put the stamp of NCR onto CTRs companies and his favorite slogan, THINK, became a mantra for each companys employees. During Watsons first four years, revenues more than doubled to $9 million, Watson had never liked the clumsy hyphenated title of the CTR and in 1924 chose to replace it with the more expansive title International Business Machines. By 1933 most of the subsidiaries had been merged into one company, in 1937, IBMs tabulating equipment enabled organizations to process unprecedented amounts of data, its clients including the U. S. During the Second World War the company produced small arms for the American war effort, in 1949, Thomas Watson, Sr. created IBM World Trade Corporation, a subsidiary of IBM focused on foreign operations. In 1952, he stepped down after almost 40 years at the company helm, in 1957, the FORTRAN scientific programming language was developed. In 1961, IBM developed the SABRE reservation system for American Airlines, in 1963, IBM employees and computers helped NASA track the orbital flight of the Mercury astronauts. A year later it moved its headquarters from New York City to Armonk. The latter half of the 1960s saw IBM continue its support of space exploration, on April 7,1964, IBM announced the first computer system family, the IBM System/360
21.
Digital Equipment Corporation
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Digital Equipment Corporation, also known as DEC and using the trademark Digital, was a major American company in the computer industry from the 1950s to the 1990s. DEC was a vendor of computer systems, including computers, software. Their PDP and successor VAX products were the most successful of all minicomputers in terms of sales, DEC was acquired in June 1998 by Compaq, in what was at that time the largest merger in the history of the computer industry. At the time, Compaq was focused on the market and had recently purchased several other large vendors. DEC was a major player overseas where Compaq had less presence, however, Compaq had little idea what to do with its acquisitions, and soon found itself in financial difficulty of its own. The company subsequently merged with Hewlett-Packard in May 2002, as of 2007 some of DECs product lines were still produced under the HP name. From 1957 until 1992, DECs headquarters were located in a wool mill in Maynard. DEC was acquired in June 1998 by Compaq, which merged with Hewlett-Packard in May 2002. Some parts of DEC, notably the business and the Hudson. Initially focusing on the end of the computer market allowed DEC to grow without its potential competitors making serious efforts to compete with them. Their PDP series of machines became popular in the 1960s, especially the PDP-8, looking to simplify and update their line, DEC replaced most of their smaller machines with the PDP-11 in 1970, eventually selling over 600,000 units and cementing DECs position in the industry. Originally designed as a follow-on to the PDP-11, DECs VAX-11 series was the first widely used 32-bit minicomputer and these systems were able to compete in many roles with larger mainframe computers, such as the IBM System/370. The VAX was a best-seller, with over 400,000 sold, at its peak, DEC was the second largest employer in Massachusetts, second only to the Massachusetts State Government. The rapid rise of the business microcomputer in the late 1980s, DECs last major attempt to find a space in the rapidly changing market was the DEC Alpha 64-bit RISC instruction set architecture. DEC initially started work on Alpha as a way to re-implement their VAX series, DEC was acquired in June 1998 by Compaq, in what was at that time the largest merger in the history of the computer industry. At the time, Compaq was focused on the market and had recently purchased several other large vendors. DEC was a major player overseas where Compaq had less presence, however, Compaq had little idea what to do with its acquisitions, and soon found itself in financial difficulty of its own. The company subsequently merged with Hewlett-Packard in May 2002, as of 2007 some of DECs product lines were still produced under the HP name
22.
DECSYSTEM-20
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The DECSYSTEM-20 was a 36-bit Digital Equipment Corporation PDP-10 mainframe computer running the TOPS-20 operating system. PDP-10 computers running the TOPS-10 operating system were labeled DECsystem-10 as a way of differentiating them from the PDP-11, later on, those systems running TOPS-20 were labeled DECSYSTEM-20. The DECSYSTEM-20 was sometimes called PDP-20, although this designation was never used by DEC, most machines sold to run TOPS-10 were painted Blasi Blue, whereas most TOPS-20 machines were painted Terracotta. Model As used the original PDP-10 memory bus, with external memory modules, the later Model B processors used in the DECSYSTEM-20 used internal memory, mounted in the same cabinet as the CPU. The Model As also had different packaging, they came in the original tall PDP-10 cabinets, the last released implementation of DECs 36-bit architecture was the single cabinet DECSYSTEM-2020, using a KS10 processor. The DECSYSTEM-20 was primarily designed and used as a small mainframe for timesharing and that is, multiple users would concurrently log on to individual user accounts and share use of the main processor to compile and run applications. Separate disk allocations were maintained for all users by the system, and various levels of protection could be maintained by for System, Owner, Group. A model 2060, for example, could typically host up to 40 to 60 simultaneous users before exhibiting noticeably reduced response time, the Living Computer Museum of Seattle, Washington maintains a 2065 running TOPS-10, which is available to interested parties via telnet upon registration at their website. This article is based in part on the Jargon File, which is in the public domain
23.
Intertec Superbrain
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The Intertec Superbrain was an all-in-one commercial microcomputer first sold by Intertec Data Systems Corp. in 1979. The machine ran the operating system CP/M and was unusual in that it used dual Z80 CPUs. In 1983, the basic machine sold for about $2000, there were several variants, including the Superbrain II, Superbrain II Jr. QD and SD models. The Superbrain is notable for being at the end of the first Kermit connection in 1981. The machine was practical and useful in the environment. This was soon replaced by the 10MB Winchester thus effectively removing all limitations on what could be programmed and stored
24.
CP/M
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Initially confined to single-tasking on 8-bit processors and no more than 64 kilobytes of memory, later versions of CP/M added multi-user variations and were migrated to 16-bit processors. The combination of CP/M and S-100 bus computers was loosely patterned on the MITS Altair and this computer platform was widely used in business through the late 1970s and into the mid-1980s. CP/M increased the size for both hardware and software by greatly reducing the amount of programming required to install an application on a new manufacturers computer. An important driver of innovation was the advent of low-cost microcomputers running CP/M, as independent programmers and hackers bought them. CP/M was displaced by MS-DOS soon after the 1981 introduction of the IBM PC, manufacturers of CP/M-compatible systems customized portions of the operating system for their own combination of installed memory, disk drives, and console devices. CP/M would also run on based on the Zilog Z80 processor since the Z80 was compatible with 8080 code. CP/M used the 7-bit ASCII set, the other 128 characters made possible by the 8-bit byte were not standardized. For example, one Kaypro used them for Greek characters, WordStar used the 8th bit as an end-of-word marker. The BIOS and BDOS were memory-resident, while the CCP was memory-resident unless overwritten by an application, a number of transient commands for standard utilities were also provided. The transient commands resided in files with the extension. COM on disk, the BIOS directly controlled hardware components other than the CPU and main memory. It contained functions such as input and output and the reading and writing of disk sectors. The BDOS implemented the CP/M file system and some input/output abstractions on top of the BIOS, the CCP took user commands and either executed them directly or loaded and started an executable file of the given name. Third-party applications for CP/M were also essentially transient commands, the BDOS, CCP and standard transient commands were the same in all installations of a particular revision of CP/M, but the BIOS portion was always adapted to the particular hardware. Adding memory to a computer, for example, meant that the CP/M system had to be reinstalled with an updated BIOS capable of addressing the additional memory, a utility was provided to patch the supplied BIOS, BDOS and CCP to allow them to be run from higher memory. Once installed, the system was stored in reserved areas at the beginning of any disk which would be used to boot the system. On start-up, the bootloader would load the system from the disk in drive A. By modern standards CP/M was primitive, owing to the constraints on program size. With version 1.0 there was no provision for detecting a changed disk, if a user changed disks without manually rereading the disk directory the system would write on the new disk using the old disks directory information, ruining the data stored on the disk
25.
IBM Personal Computer
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The IBM Personal Computer, commonly known as the IBM PC, is the original version and progenitor of the IBM PC compatible hardware platform. It is IBM model number 5150, and was introduced on August 12,1981 and it was created by a team of engineers and designers under the direction of Don Estridge of the IBM Entry Systems Division in Boca Raton, Florida. IBM compatible became an important criterion for sales growth, only the Apple Macintosh family kept significant market share without compatibility with the IBM personal computer, International Business Machines, one of the worlds largest companies, had a 62% share of the mainframe computer market in 1981. Its share of the computer market, however, had declined from 60% in 1970 to 32% in 1980. In 1979 BusinessWeek asked, Is IBM just another stodgy, mature company, by 1981 its stock price had declined by 22%. IBMs earnings for the first half the year grew by 5. 3%—one third of the inflation rate—while those of minicomputer maker Digital Equipment Corporation grew by more than 35%. B. M, No longer dominates the computer business. IBM wished to avoid the outcome with the new personal computer industry, dominated by the Commodore PET, Atari 8-bit family, Apple II, Tandy Corporations TRS-80. With $150 million in sales by 1979 and projected growth of more than 40% in the early 1980s. The Japanese project, codenamed Go, ended before the 1981 release of the American-designed IBM PC codenamed Chess, whether IBM had waited too long to enter an industry in which Apple and others were already successful was unclear. An observer stated that IBM bringing out a computer would be like teaching an elephant to tap dance. Successful microcomputer company Vector Graphics fiscal 1980 revenue was $12 million, the company only sold through its internal sales force, had no experience with resellers or retail stores, and did not introduce the first product designed to work with non-IBM equipment until 1980. Another observer claimed that IBM made decisions so slowly that, when tested, as with other large computer companies, its new products typically required about four to five years for development. IBM had to learn how to develop, mass-produce. The potential importance to microcomputers of a company so prestigious, that a saying in American companies stated No one ever got fired for buying IBM, was nonetheless clear. InfoWorld, which described itself as The Newsweekly for Microcomputer Users, stated that for my grandmother, is far and away the media star, not because of its features, but because it exists at all. When the number eight company in the Fortune 500 enters the field, the influence of a personal computer made by a company whose name has literally come to mean computer to most of the world is hard to contemplate. The editorial acknowledged that some factions in our industry have looked upon IBM as the enemy, desktop sized programmable calculators by Hewlett Packard had evolved into the HP9830 BASIC language computer by 1972. In 1972–1973 a team led by Dr. SCAMP emulated an IBM1130 minicomputer to run APL\1130, in 1973 APL was generally available only on mainframe computers, and most desktop sized microcomputers such as the Wang 2200 or HP9800 offered only BASIC
26.
International Space Station
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The International Space Station is a space station, or a habitable artificial satellite, in low Earth orbit. Its first component launched into orbit in 1998, and the ISS is now the largest man-made body in space, the ISS consists of pressurised modules, external trusses, solar arrays, and other components. ISS components have been launched by Russian Proton and Soyuz rockets, the ISS serves as a microgravity and space environment research laboratory in which crew members conduct experiments in biology, human biology, physics, astronomy, meteorology, and other fields. The station is suited for the testing of systems and equipment required for missions to the Moon. The ISS maintains an orbit with an altitude of between 330 and 435 km by means of reboost manoeuvres using the engines of the Zvezda module or visiting spacecraft and it completes 15.54 orbits per day. The ISS is the space station to be inhabited by crews, following the Soviet and later Russian Salyut, Almaz. The station has continuously occupied for 16 years and 156 days since the arrival of Expedition 1 on 2 November 2000. This is the longest continuous presence in low Earth orbit. It has been visited by astronauts, cosmonauts and space tourists from 17 different nations, Soyuz has very limited downmass capability. The ISS programme is a joint project among five participating space agencies, NASA, Roscosmos, JAXA, ESA, the ownership and use of the space station is established by intergovernmental treaties and agreements. The station is divided two sections, the Russian Orbital Segment and the United States Orbital Segment, which is shared by many nations. As of January 2014, the American portion of ISS is being funded until 2024, Roscosmos has endorsed the continued operation of ISS through 2024 but has proposed using elements of the Russian Orbital Segment to construct a new Russian space station called OPSEK. On 28 March 2015, Russian sources announced that Roscosmos and NASA had agreed to collaborate on the development of a replacement for the current ISS. NASA later issued a statement expressing thanks for Russias interest in future co-operation in space exploration. According to the original Memorandum of Understanding between NASA and Rosaviakosmos, the International Space Station was intended to be a laboratory, observatory and factory in low Earth orbit. It was also planned to provide transportation, maintenance, and act as a base for possible future missions to the Moon, Mars. In the 2010 United States National Space Policy, the ISS was given roles of serving commercial, diplomatic. The ISS provides a platform to conduct scientific research, the ISS simplifies individual experiments by eliminating the need for separate rocket launches and research staff
27.
Minicomputer
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A minicomputer, or colloquially mini, is a class of smaller computers that developed in the mid-1960s and sold for much less than mainframe and mid-size computers from IBM and its direct competitors. The class formed a group with its own software architectures. Minis were designed for control, instrumentation, human interaction, and communication switching as distinct from calculation, many were sold indirectly to Original Equipment Manufacturers for final end use application. During the two decade lifetime of the class, almost 100 companies formed and only a half dozen remained. They usually took up one or a few 19-inch rack cabinets, the definition of minicomputer is vague with the consequence that there are a number of candidates for the first minicomputer. An early and highly successful minicomputer was Digital Equipment Corporations 12-bit PDP-8, later versions of the PDP-8 took advantage of small-scale integrated circuits. The important precursors of the PDP-8 include the PDP-5, LINC, the TX-0, the TX-2, DEC gave rise to a number of minicomputer companies along Massachusetts Route 128, including Data General, Wang Laboratories, Apollo Computer, and Prime Computer. Minicomputers were also known as midrange computers and they grew to have relatively high processing power and capacity. They were used in manufacturing process control, telephone switching and to control laboratory equipment, in the 1970s, they were the hardware that was used to launch the computer-aided design industry and other similar industries where a smaller dedicated system was needed. The 7400 series of TTL integrated circuits started appearing in minicomputers in the late 1960s, the 74181 arithmetic logic unit was commonly used in the CPU data paths. Each 74181 had a bus width of four bits, hence the popularity of bit-slice architecture, some scientific computers, such as the Nicolet 1080, would use the 7400 series in groups of five ICs for their uncommon twenty bits architecture. Starting in the 1980s, many minicomputers used VLSI circuits, the result was that minicomputers and computer terminals were replaced by networked workstations, file servers and PCs in some installations, beginning in the latter half of the 1980s. Also, the Microsoft Windows series of operating systems, beginning with Windows NT, now included server versions that supported preemptive multitasking, Digital Equipment Corporation was once the leading minicomputer manufacturer, at one time the second-largest computer company after IBM. DEC was sold to Compaq in 1998, while Data General was acquired by EMC Corporation, today only a few proprietary minicomputer architectures survive. The IBM System/38 operating system, which introduced many advanced concepts, realising the importance of the myriad lines of legacy code written, AS stands for Application System. Great efforts were made by IBM to enable programs written for the System/34. The AS/400 was replaced by the iSeries, which was replaced by the System i. In 2008, the System i was replaced by the IBM Power Systems, by contrast, competing proprietary computing architectures from the early 1980s, such as DECs VAX, Wang VS and Hewlett Packards HP3000 have long been discontinued without a compatible upgrade path
28.
Serial port
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In computing, a serial port is a serial communication interface through which information transfers in or out one bit at a time. Throughout most of the history of computers, data was transferred through serial ports to devices such as modems, terminals. Modern computers without serial ports may require serial-to-USB converters to allow compatibility with RS-232 serial devices, serial ports are still used in applications such as industrial automation systems, scientific instruments, point of sale systems and some industrial and consumer products. Server computers may use a port as a control console for diagnostics. Network equipment often use serial console for configuration, serial ports are still used in these areas as they are simple, cheap and their console functions are highly standardized and widespread. A serial port requires very little supporting software from the host system, some computers, such as the IBM PC, use an integrated circuit called a UART. This IC converts characters to and from asynchronous serial form, implementing the timing and framing of data in hardware, very low-cost systems, such as some early home computers, would instead use the CPU to send the data through an output pin, using the bit-banging technique. Early home computers often had proprietary serial ports with pinouts and voltage levels incompatible with RS-232, low-cost processors now allow higher-speed, but more complex, serial communication standards such as USB and FireWire to replace RS-232. These make it possible to connect devices that would not have operated feasibly over slower serial connections, such as storage, sound. Many personal computer motherboards still have at least one serial port, small-form-factor systems and laptops may omit RS-232 connector ports to conserve space, but the electronics are still there. RS-232 has been standard for so long that the circuits needed to control a serial port became very cheap and often exist on a single chip, sometimes also with circuitry for a parallel port. The individual signals on a serial port are unidirectional and when connecting two devices the outputs of one device must be connected to the inputs of the other, devices are divided into two categories data terminal equipment and data circuit-terminating equipment. A line that is an output on a DTE device is an input on a DCE device and vice versa so a DCE device can be connected to a DTE device with a straight wired cable, conventionally, computers and terminals are DTE while modems and peripherals are DCE. If it is necessary to connect two DTE devices a cross-over null modem, in the form of either an adapter or a cable, generally, serial port connectors are gendered, only allowing connectors to mate with a connector of the opposite gender. With D-subminiature connectors, the male connectors have protruding pins, either type of connector can be mounted on equipment or a panel, or terminate a cable. Connectors mounted on DTE are likely to be male, and those mounted on DCE are likely to be female, however, this is far from universal, for instance, most serial printers have a female DB25 connector, but they are DTEs. The desire to supply serial interface cards with two ports required that IBM reduce the size of the connector to fit onto a single card back panel, a DE-9 connector also fits onto a card with a second DB-25 connector. Starting around the time of the introduction of the IBM PC-AT, serial ports were built with a 9-pin connector to save cost
29.
C (programming language)
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C was originally developed by Dennis Ritchie between 1969 and 1973 at Bell Labs, and used to re-implement the Unix operating system. C has been standardized by the American National Standards Institute since 1989, C is an imperative procedural language. Therefore, C was useful for applications that had formerly been coded in assembly language. Despite its low-level capabilities, the language was designed to encourage cross-platform programming, a standards-compliant and portably written C program can be compiled for a very wide variety of computer platforms and operating systems with few changes to its source code. The language has become available on a wide range of platforms. In C, all code is contained within subroutines, which are called functions. Function parameters are passed by value. Pass-by-reference is simulated in C by explicitly passing pointer values, C program source text is free-format, using the semicolon as a statement terminator and curly braces for grouping blocks of statements. The C language also exhibits the characteristics, There is a small, fixed number of keywords, including a full set of flow of control primitives, for, if/else, while, switch. User-defined names are not distinguished from keywords by any kind of sigil, There are a large number of arithmetical and logical operators, such as +, +=, ++, &, ~, etc. More than one assignment may be performed in a single statement, function return values can be ignored when not needed. Typing is static, but weakly enforced, all data has a type, C has no define keyword, instead, a statement beginning with the name of a type is taken as a declaration. There is no function keyword, instead, a function is indicated by the parentheses of an argument list, user-defined and compound types are possible. Heterogeneous aggregate data types allow related data elements to be accessed and assigned as a unit, array indexing is a secondary notation, defined in terms of pointer arithmetic. Unlike structs, arrays are not first-class objects, they cannot be assigned or compared using single built-in operators, There is no array keyword, in use or definition, instead, square brackets indicate arrays syntactically, for example month. Enumerated types are possible with the enum keyword and they are not tagged, and are freely interconvertible with integers. Strings are not a data type, but are conventionally implemented as null-terminated arrays of characters. Low-level access to memory is possible by converting machine addresses to typed pointers
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Unix
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Among these is Apples macOS, which is the Unix version with the largest installed base as of 2014. Many Unix-like operating systems have arisen over the years, of which Linux is the most popular, Unix was originally meant to be a convenient platform for programmers developing software to be run on it and on other systems, rather than for non-programmer users. The system grew larger as the system started spreading in academic circles, as users added their own tools to the system. Unix was designed to be portable, multi-tasking and multi-user in a time-sharing configuration and these concepts are collectively known as the Unix philosophy. By the early 1980s users began seeing Unix as a universal operating system. Under Unix, the system consists of many utilities along with the master control program. To mediate such access, the kernel has special rights, reflected in the division between user space and kernel space, the microkernel concept was introduced in an effort to reverse the trend towards larger kernels and return to a system in which most tasks were completed by smaller utilities. In an era when a standard computer consisted of a disk for storage and a data terminal for input and output. However, modern systems include networking and other new devices, as graphical user interfaces developed, the file model proved inadequate to the task of handling asynchronous events such as those generated by a mouse. In the 1980s, non-blocking I/O and the set of inter-process communication mechanisms were augmented with Unix domain sockets, shared memory, message queues, and semaphores. In microkernel implementations, functions such as network protocols could be moved out of the kernel, Multics introduced many innovations, but had many problems. Frustrated by the size and complexity of Multics but not by the aims and their last researchers to leave Multics, Ken Thompson, Dennis Ritchie, M. D. McIlroy, and J. F. Ossanna, decided to redo the work on a much smaller scale. The name Unics, a pun on Multics, was suggested for the project in 1970. Peter H. Salus credits Peter Neumann with the pun, while Brian Kernighan claims the coining for himself, in 1972, Unix was rewritten in the C programming language. Bell Labs produced several versions of Unix that are referred to as Research Unix. In 1975, the first source license for UNIX was sold to faculty at the University of Illinois Department of Computer Science, UIUC graduate student Greg Chesson was instrumental in negotiating the terms of this license. During the late 1970s and early 1980s, the influence of Unix in academic circles led to adoption of Unix by commercial startups, including Sequent, HP-UX, Solaris, AIX. In the late 1980s, AT&T Unix System Laboratories and Sun Microsystems developed System V Release 4, in the 1990s, Unix-like systems grew in popularity as Linux and BSD distributions were developed through collaboration by a worldwide network of programmers
31.
OpenVMS
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OpenVMS is a computer operating system for use in general-purpose computing. It is the successor to the VMS Operating System, that was produced by Digital Equipment Corporation, in the 1990s, it was used for the successor series of DEC Alpha systems. OpenVMS also runs on the HP Itanium-based families of computers, as of 2015, a port to the X86-64 architecture is underway. The name VMS is derived from virtual memory system, according to one of its architectural features. OpenVMS is a operating system, but source code listings are available for purchase. OpenVMS is a multi-user, multiprocessing virtual memory-based operating system designed for use in time sharing, batch processing, when process priorities are suitably adjusted, it may approach real-time operating system characteristics. The system offers high availability through clustering and the ability to distribute the system over multiple physical machines and this allows the system to be tolerant against disasters that may disable individual data-processing facilities. OpenVMS contains a user interface, a feature that was not available on the original VAX-11/VMS system. Versions of VMS running on DEC Alpha workstations in the 1990s supported OpenGL, customers using OpenVMS include banks and financial services, hospitals and healthcare, network information services, and large-scale industrial manufacturers of various products. As of mid-2014, Hewlett Packard licensed the development of OpenVMS exclusively to VMS Software Inc, VMS Software will be responsible for developing OpenVMS, supporting existing hardware and providing roadmap to clients. The company has a team of developers that originally developed the software during DECs ownership. In April 1975, Digital Equipment Corporation embarked on a project, code named Star. A companion software project, code named Starlet, was started in June 1975 to develop a new operating system, based on RSX-11M. These two projects were integrated from the beginning. Gordon Bell was the VP lead on the VAX hardware and its architecture, the Star and Starlet projects culminated in the VAX 11/780 computer and the VAX-11/VMS operating system. The Starlet name survived in VMS as a name of several of the system libraries, including STARLET. OLB. Over the years the name of the product has changed, in 1980 it was renamed, with version 2.0 release, to VAX/VMS. g. The smallest MicroVAX2000 had a 40MB RD32 hard disk and a maximum of 6MB of RAM, microVMS kits were released for VAX/VMS4.4 to 4.7 on TK50 tapes and RX50 floppy disks, but discontinued with VAX/VMS5.0
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Microsoft Windows
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Microsoft Windows is a metafamily of graphical operating systems developed, marketed, and sold by Microsoft. It consists of families of operating systems, each of which cater to a certain sector of the computing industry with the OS typically associated with IBM PC compatible architecture. Active Windows families include Windows NT, Windows Embedded and Windows Phone, defunct Windows families include Windows 9x, Windows 10 Mobile is an active product, unrelated to the defunct family Windows Mobile. Microsoft introduced an operating environment named Windows on November 20,1985, Microsoft Windows came to dominate the worlds personal computer market with over 90% market share, overtaking Mac OS, which had been introduced in 1984. Apple came to see Windows as an encroachment on their innovation in GUI development as implemented on products such as the Lisa. On PCs, Windows is still the most popular operating system, however, in 2014, Microsoft admitted losing the majority of the overall operating system market to Android, because of the massive growth in sales of Android smartphones. In 2014, the number of Windows devices sold was less than 25% that of Android devices sold and this comparison however may not be fully relevant, as the two operating systems traditionally target different platforms. As of September 2016, the most recent version of Windows for PCs, tablets, smartphones, the most recent versions for server computers is Windows Server 2016. A specialized version of Windows runs on the Xbox One game console, Microsoft, the developer of Windows, has registered several trademarks each of which denote a family of Windows operating systems that target a specific sector of the computing industry. It now consists of three operating system subfamilies that are released almost at the time and share the same kernel. Windows, The operating system for personal computers, tablets. The latest version is Windows 10, the main competitor of this family is macOS by Apple Inc. for personal computers and Android for mobile devices. Windows Server, The operating system for server computers, the latest version is Windows Server 2016. Unlike its clients sibling, it has adopted a strong naming scheme, the main competitor of this family is Linux. Windows PE, A lightweight version of its Windows sibling meant to operate as an operating system, used for installing Windows on bare-metal computers. The latest version is Windows PE10.0.10586.0, Windows Embedded, Initially, Microsoft developed Windows CE as a general-purpose operating system for every device that was too resource-limited to be called a full-fledged computer. The following Windows families are no longer being developed, Windows 9x, Microsoft now caters to the consumers market with Windows NT. Windows Mobile, The predecessor to Windows Phone, it was a mobile operating system
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Windows 95
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Windows 95 is a consumer-oriented operating system developed by Microsoft. It was released on August 24,1995, and was a significant improvement over the companys previous DOS-based Windows products, Windows 95 merged Microsofts formerly separate MS-DOS and Windows products. It featured significant improvements over its predecessor, Windows 3.1, most notably in the user interface. It was also suggested that Windows 95 had an effect of driving other major out of business. Three years after its introduction, Windows 95 was succeeded by Windows 98, Microsoft ended support for Windows 95 on December 31,2001. The initial design and planning of Windows 95 can be traced back to around March 1992, at this time, Windows for Workgroups 3.11 and Windows NT3.1 were still in development and Microsofts plan for the future was focused on Cairo. Cairo would be Microsofts next-generation operating system based on Windows NT and featuring a new interface and an object-based file system. However, Cairo would partially ship in July 1996 in the form of Windows NT4.0, but without the object-based file system, simultaneously with Windows 3. 1s release, IBM started shipping OS/22.0. Microsoft realized they were in need of a version of Windows that could support 32-bit applications and preemptive multitasking. So the development of Windows Chicago was started and, as it was planned for a late 1993 release, became known as Windows 93. Initially, the decision was not to include a new user interface, as this was planned for Cairo, and only focus on making installation, configuration. Windows 93 would ship together with MS-DOS7.0, offering an integrated experience to the user. The first version of Chicagos feature specification was finished on September 30,1992, cougar was to become Chicagos kernel. Prior to Windows 95s official release, users in the United States had an opportunity to preview it in the Windows 95 Preview Program. For US$19.95, users would receive several 3. 5-inch floppy disks that would be used to install Windows 95 either as an upgrade from Windows 3. 1x or as a fresh installation. Participants were also given a preview of The Microsoft Network. The preview versions expired in November 1995, after which the user would have to purchase their own copy of the version of Windows 95. Windows 95 was designed to be compatible with existing MS-DOS and 16-bit Windows programs and device drivers, while offering a more stable
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OS/2
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OS/2 is a series of computer operating systems, initially created by Microsoft and IBM, then later developed by IBM exclusively. The name stands for Operating System/2, because it was introduced as part of the generation change release as IBMs Personal System/2 line of second-generation personal computers. The first version of OS/2 was released in December 1987 and newer versions were released until December 2001, OS/2 was intended as a protected mode successor of PC DOS. Because of this heritage, OS/2 shares similarities with Unix, Xenix, IBM discontinued its support for OS/2 on 31 December 2006. Since then, it has been updated, maintained and marketed under the name eComStation, in 2015 it was announced that a new OEM distribution of OS/2 would be released that was to be called ArcaOS. The development of OS/2 began when IBM and Microsoft signed the Joint Development Agreement in August 1985 and it was code-named CP/DOS and it took two years for the first product to be delivered. OS/21.0 was announced in April 1987 and released in December, the original release is textmode-only, and a GUI was introduced with OS/21.1 about a year later. OS/2 features an API for controlling the display and handling keyboard. In addition, development tools include a subset of the video, a task-switcher named Program Selector is available through the Ctrl-Esc hotkey combination, allowing the user to select among multitasked text-mode sessions. Communications and database-oriented extensions were delivered in 1988, as part of OS/21.0 Extended Edition, SNA, X. 25/APPC/LU6.2, LAN Manager, Query Manager, SQL. The promised graphical user interface, Presentation Manager, was introduced with OS/21.1 in October,1988 and it had a similar user interface to Windows 2.1, which was released in May of that year. The Extended Edition of 1.1, sold only through IBM sales channels, introduced distributed database support to IBM database systems, in 1989, Version 1.2 introduced Installable Filesystems and notably the HPFS filesystem. HPFS provided a number of improvements over the older FAT file system, including long filenames, in addition, extended attributes were also added to the FAT file system. The Extended Edition of 1.2 introduced TCP/IP and Ethernet support, OS/2 and Windows-related books of the late 1980s acknowledged the existence of both systems and promoted OS/2 as the system for the future. The collaboration between IBM and Microsoft unravelled in 1990, between the releases of Windows 3.0 and OS/21.3, during this time, Windows 3.0 became a tremendous success, selling millions of copies in its first year. Much of its success was because Windows 3.0 was bundled with most new computers, OS/2, on the other hand, was available only as an expensive stand-alone software package. In addition, OS/2 lacked device drivers for many devices such as printers. Windows, on the hand, supported a much larger variety of hardware
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Open-source model
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Open-source software may be developed in a collaborative public manner. According to scientists who studied it, open-source software is a prominent example of open collaboration, a 2008 report by the Standish Group states that adoption of open-source software models has resulted in savings of about $60 billion per year to consumers. In the early days of computing, programmers and developers shared software in order to learn from each other, eventually the open source notion moved to the way side of commercialization of software in the years 1970-1980. In 1997, Eric Raymond published The Cathedral and the Bazaar and this source code subsequently became the basis behind SeaMonkey, Mozilla Firefox, Thunderbird and KompoZer. Netscapes act prompted Raymond and others to look into how to bring the Free Software Foundations free software ideas, the new term they chose was open source, which was soon adopted by Bruce Perens, publisher Tim OReilly, Linus Torvalds, and others. The Open Source Initiative was founded in February 1998 to encourage use of the new term, a Microsoft executive publicly stated in 2001 that open source is an intellectual property destroyer. I cant imagine something that could be worse than this for the software business, IBM, Oracle, Google and State Farm are just a few of the companies with a serious public stake in todays competitive open-source market. There has been a significant shift in the corporate philosophy concerning the development of FOSS, the free software movement was launched in 1983. In 1998, a group of individuals advocated that the free software should be replaced by open-source software as an expression which is less ambiguous. Software developers may want to publish their software with an open-source license, the Open Source Definition, notably, presents an open-source philosophy, and further defines the terms of usage, modification and redistribution of open-source software. Software licenses grant rights to users which would otherwise be reserved by law to the copyright holder. Several open-source software licenses have qualified within the boundaries of the Open Source Definition, the open source label came out of a strategy session held on April 7,1998 in Palo Alto in reaction to Netscapes January 1998 announcement of a source code release for Navigator. They used the opportunity before the release of Navigators source code to clarify a potential confusion caused by the ambiguity of the free in English. Many people claimed that the birth of the Internet, since 1969, started the open source movement, the Free Software Foundation, started in 1985, intended the word free to mean freedom to distribute and not freedom from cost. Since a great deal of free software already was free of charge, such software became associated with zero cost. The Open Source Initiative was formed in February 1998 by Eric Raymond and they sought to bring a higher profile to the practical benefits of freely available source code, and they wanted to bring major software businesses and other high-tech industries into open source. Perens attempted to open source as a service mark for the OSI. The Open Source Initiatives definition is recognized by governments internationally as the standard or de facto definition, OSI uses The Open Source Definition to determine whether it considers a software license open source
