1.
Emacs
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Emacs /ˈiːmæks/ and its derivatives are a family of text editors that are characterized by their extensibility. The manual for the most widely used variant, GNU Emacs, describes it as the extensible, customizable, self-documenting, development of the first Emacs began in the mid-1970s and continues actively as of 2017. Emacs has over 2,000 built-in commands and allows the user to combine these commands into macros to automate work, Emacs Lisp provides a deep extension capability allowing users and developers to write new commands using a dialect of the Lisp programming language. Extensions have been written to manage email, files, outlines, the original EMACS was written in 1976 by David A. Moon and Guy L. Steele, Jr. as a set of Editor MACroS for the TECO editor. It was inspired by the ideas of the TECO-macro editors TECMAC, the most popular, and most ported, version of Emacs is GNU Emacs, which was created by Richard Stallman for the GNU Project. XEmacs is a variant that branched from GNU Emacs in 1991, both GNU Emacs and XEmacs use Emacs Lisp and are for the most part compatible with each other. Emacs is, along with vi, one of the two contenders in the traditional editor wars of Unix culture. Both are among the oldest application programs still in use, unlike most modern text editors, TECO used separate modes in which the user would either add text, edit existing text, or display the document. This behavior is similar to that of the program ed. Richard Stallman visited the Stanford AI Lab in 1972 or 1974 and saw the labs E editor and he was impressed by the editors intuitive WYSIWYG behavior, which has since become the default behavior of most modern text editors. Stallman reimplemented this mode to run efficiently and then added a feature to the TECO display-editing mode that allowed the user to redefine any keystroke to run a TECO program. E had another feature that TECO lacked, random-access editing, TECO was a page-sequential editor that was designed for editing paper tape on the PDP-1 and typically allowed editing on only one page at a time, in the order of the pages in the file. Almost all modern editors use this approach, the new version of TECO quickly became popular at the AI Lab and soon accumulated a large collection of custom macros whose names often ended in MAC or MACS, which stood for macro. Two years later, Guy Steele took on the project of unifying the overly diverse macros into a single set, Steele and Stallmans finished implementation included facilities for extending and documenting the new macro set. The resulting system was called EMACS, which stood for Editing MACroS or, alternatively, Stallman picked the name Emacs because <E> was not in use as an abbreviation on ITS at the time. An apocryphal hacker koan alleges that the program was named after Emack & Bolios, the first operational EMACS system existed in late 1976. Stallman saw a problem in too much customization and de facto forking and he later wrote, EMACS was distributed on a basis of communal sharing, which means all improvements must be given back to me to be incorporated and distributed. The original Emacs, like TECO, ran only on the PDP-10 running ITS and its behavior was sufficiently different from that of TECO that it could be considered a text editor in its own right, and it quickly became the standard editing program on ITS. Mike McMahon ported Emacs from ITS to the TENEX and TOPS-20 operating systems, other contributors to early versions of Emacs include Kent Pitman, Earl Killian, and Eugene Ciccarelli
2.
Vi
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Vi /ˈviːˈaɪ/ is a screen-oriented text editor originally created for the Unix operating system. The portable subset of the behavior of vi and programs based on it, the original code for vi was written by Bill Joy in 1976, as the visual mode for a line editor called ex that Joy had written with Chuck Haley. Bill Joys ex 1.1 was released as part of the first BSD Unix release in March,1978. It was not until version 2.0 of ex, released as part of Second Berkeley Software Distribution in May,1979 that the editor was installed under the name vi, and the name by which it is known today. Some current implementations of vi can trace their source code ancestry to Bill Joy, others are completely new, the name vi is derived from the shortest unambiguous abbreviation for the ex command visual, which switches the ex line editor to visual mode. The name vi is pronounced /ˈviːˈaɪ/, a 2009 survey of Linux Journal readers found that vi was the most widely used text editor among respondents, beating gedit, the second most widely used editor, by nearly a factor of two. Vi was derived from a sequence of UNIX command line editors, starting with ed, which was a line editor designed to work well on teletypes, rather than display terminals. Within AT&T Corporation, where ed originated, people seemed to be happy with an editor as basic and unfriendly as ed, George Coulouris recalls, for many years, they had no suitable terminals. They carried on with TTYs and other printing terminals for a time. These were large storage tube displays and you cant run a screen editor on a storage-tube display as the picture cant be updated. Thus it had to fall to someone else to pioneer screen editing for Unix, and that was us initially, and we continued to do so for many years. Coulouris considered the cryptic commands of ed to be suitable for immortals. The em editor was designed for display terminals and was a visual editor. It was one of the first programs on Unix to make use of raw terminal input mode, in which the running program, rather than the terminal device driver. When Coulouris visited UC Berkeley in the summer of 1976, he brought a DECtape containing em, some people considered this new kind of editor to be a potential resource hog, but others, including Bill Joy were impressed. Inspired by em, and by their own tweaks to ed, Bill Joy and Chuck Haley, after Haleys departure, Bruce Englar encouraged Joy to redesign the editor, which he did June through October 1977 adding a full-screen visual mode to ex. Many of the ideas in exs visual mode were taken from software that existed at the time. According to Bill Joy, inspiration for vis visual mode came from the Bravo editor, in an interview about vis origins, Joy said, A lot of the ideas for the screen editing mode were stolen from a Bravo manual I surreptitiously looked at and copied
3.
Vim (text editor)
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Vim is a clone of Bill Joys vi text editor program for Unix. It was written by Bram Moolenaar based on source for a port of the Stevie editor to the Amiga, Vim is designed for use both from a command-line interface and as a standalone application in a graphical user interface. Vim is free and open software and is released under a license that includes some charityware clauses. The license is compatible with the GNU General Public License, although Vim was originally released for the Amiga, Vim has since been developed to be cross-platform, supporting many other platforms. Bram Moolenaar began working on Vim for the Amiga computer in 1988, Moolenaar first publicly released Vim in 1991. Vim was based on an editor, Stevie, for the Atari ST, created by Tim Thompson, Tony Andrews. The name Vim is an acronym for Vi IMproved because Vim is a version of the vi editor. Originally, the acronym stood for Vi IMitation, but that was changed with the release of Vim 2.0 in December 1993, a later comment states that the reason for changing the name was that Vims feature set surpassed that of vi. Vi tends to allow a typist to keep their fingers on the home row, Vim has a built-in tutorial for beginners. There is also the Vim Users Manual that details Vims features and this manual can be read from within Vim, or found online. Vim also has a built-in help facility that allows users to query and navigate through commands, part of Vims power is that it can be extensively customized. There are many available that will extend or add new functionality to Vim. These complex scripts are written in Vims internal scripting language. Vim also supports scripting using Lua, Perl, Python, Racket, Ruby, there are projects bundling together complex scripts and customizations and aimed at turning Vim into a tool for a specific task or adding a major flavour to its behaviour. Examples include Cream, which makes Vim behave like a click-and-type editor, or VimOutliner, Vim has a vi compatibility mode, but, when not in this mode, Vim has many enhancements over vi. However, even in compatibility mode, Vim is not entirely compatible with vi as defined in the Single Unix Specification, Vim has nevertheless been described as very much compatible with Vi. Vim script is the language built into Vim. Based on the ex editor language of the vi editor, early versions of Vim added commands for control flow
4.
Text editor
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A text editor is a type of program used for editing plain text files. Such programs are known as notepad software, following the Microsoft Notepad. Text editors are provided with operating systems and software development packages, there are important differences between plain text files created by a text editor and document files created by word processors such as Microsoft Word or WordPerfect. A plain text file uses a character encoding such as UTF-8 or ASCII to represent numbers, letters, the only non-printing characters in the file that can be used to format the text are newline, tab, and formfeed. Plain text files are displayed using a monospace font so horizontal alignment. Although they are viewed with formatting, documents using markup languages are stored in plain text files that contain a combination of human-readable text. For example, web pages are plain text with HTML tags to achieve formatting when rendered by a web browser, many web pages also contain embedded JavaScript that is interpreted by the browser. When both formats are available, the user must select with care, saving a plain text file in a word-processor format adds formatting information that can make the text unreadable by a program that expects plain text. Conversely, saving a document as plain text removes any formatting information. Before text editors existed, computer text was punched into cards with keypunch machines, physical boxes of these thin cardboard cards were then inserted into a card-reader. Magnetic tape and disk card-image files created from such card decks often had no characters at all. An alternative to cards was punched paper tape and it could be created by some teleprinters, which used special characters to indicate ends of records. The first text editors were line editors oriented to teleprinter- or typewriter-style terminals without displays, commands effected edits to a file at an imaginary insertion point called the cursor. Edits were verified by typing a command to print a small section of the file, in some line editors, the cursor could be moved by commands that specified the line number in the file, text strings for which to search, and eventually regular expressions. Line editors were major improvements over keypunching, some line editors could be used by keypunch, editing commands could be taken from a deck of cards and applied to a specified file. Some common line editors supported a mode in which change commands displayed the altered lines. When computer terminals with video screens became available, screen-based text editors became common, one of the earliest full-screen editors was O26, which was written for the operator console of the CDC6000 series computers in 1967. Another early full-screen editor was vi, written in the 1970s, it is still a standard editor on Unix and Linux operating systems
5.
Hacker culture
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The hacker culture is a subculture of individuals who enjoy the intellectual challenge of creatively overcoming limitations of software systems to achieve novel and clever outcomes. The act of engaging in activities in a spirit of playfulness, however, the defining characteristic of a hacker is not the activities performed themselves, but the manner in which it is done and whether it is something exciting and meaningful. Therefore, the hacker culture originally emerged in academia in the 1960s around the Massachusetts Institute of Technology s Tech Model Railroad Club, Richard Stallman explains about hackers who program, What they had in common was mainly love of excellence and programming. They wanted to make their programs that they used be as good as they could and they also wanted to make them do neat things. They wanted to be able to do something in an exciting way than anyone believed possible. I bet you didnt believe this could be done, as documented in the Jargon File, these hackers are disappointed by the mass media and general publics usage of the word hacker to refer to security breakers, calling them crackers instead. The word hacker derives from the word of a lusty laborer who harvested fields by dogged. Although the idea of hacking has existed long before the term hacker—with the most notable example of Lightning Ellsworth, in fact, many of the first programmers were from engineering or physics backgrounds. With this definition in mind, it can be clear where the negative implications of the word hacker, some common nicknames among this culture include crackers who are unskilled thieves who mainly rely on luck. Others include phreak—which refers to a type of skilled crackers and warez d00dz—which is a kind of cracker that acquires reproductions of copyrighted software, within all hackers are tiers of hackers such as the samurai who are hackers that hire themselves out for legal electronic locksmith work. Furthermore, there are other hackers who are hired to test security, the MIT Artificial Intelligence Laboratory, the University of California, Berkeley and Carnegie Mellon University were particularly well-known hotbeds of early hacker culture. Over time, the hacker subculture has tended to become more conscious, more cohesive. The concentration of academic hacker subculture has paralleled and partly driven by the commoditization of computer and networking technology. Many of the values and tenets of the free and open software movement stem from the hacker ethics that originated at MIT. Hackers should be judged by their hacking, not bogus criteria such as degrees, age, race and you can create art and beauty on a computer. Computers can change your life for the better, Hacker ethics are concerned primarily with sharing, openness, collaboration, and engaging in the hands-on imperative. Hack value is the used by hackers to express that something is worth doing or is interesting. This is something that often feel intuitively about a problem or solution
6.
Free software movement
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Although drawing on traditions and philosophies among members of the 1970s hacker culture and academia, Richard Stallman formally founded the movement in 1983 by launching the GNU Project. Stallman later established the Free Software Foundation in 1985 to support the movement, the philosophy of the movement is that the use of computers should not lead to people being prevented from cooperating with each other. Stallman notes that this action will promote rather than hinder the progression of technology and this effort can go instead into advancing the state of the art. Members of the free software movement believe that all users of software should have the freedoms listed in The Free Software Definition, while social change may occur as an unintended by-product of technological change, advocates of new technologies often have promoted them as instruments of positive social change. This quote by San Jose State professor Joel West explains much of the philosophy, if it is assumed that social change is not only affected, but in some points of view, directed by the advancement of technology, is it ethical to hold these technologies from certain people. If not to make a change, this movement is in place to raise awareness about the effects that take place because of the physical things around us. A computer, for instance, allows us so many more freedoms than we have without a computer, the debate over the morality of both sides to the free software movement is a difficult topic to compromise respective opposition. Within the free movement, the FLOSS Manuals foundation specialises on the goal of providing such documentation. Members of the free software movement advocate that works which serve a practical purpose should also be free, the core work of the free software movement focused on software development. The free software movement also rejects proprietary software, refusing to install software that does not give them the freedoms of free software, some supporters of the free software movement take up public speaking, or host a stall at software-related conferences to raise awareness of software freedom. The ideas sparked by the GNU associates are an attempt to promote an environment that understands the benefits of having a local community. A lot of lobbying work has been done against software patents, other lobbying focusses directly on use of free software by government agencies and government-funded projects. The Venezuelan government implemented a free software law in January 2006, decree No.3,390 mandated all government agencies to migrate to free software over a two-year period. Congressmen Edgar David Villanueva and Jacques Rodrich Ackerman have been instrumental in introducing free software in Peru, the incident invited the attention of got Microsoft Inc, Peru, whose general manager wrote a letter to Villanueva. His response received worldwide attention and is seen as a piece of argumentation favouring use of free software in governments. In the United States, there have been efforts to pass legislation at the state level encouraging use of software by state government agencies. Like many social movements, the free movement has ongoing internal conflict between the many FOSS organizations and their personalities. For instance there is disagreement about the amount of compromises and pragmatism needed versus the need for strict adherence to values, after this Eric Raymond and Bruce Perens founded the Open Source Initiative, to promote the term open source software as an alternative term for free software
7.
Usenet
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Usenet is a worldwide distributed discussion system available on computers. It was developed from the general-purpose UUCP dial-up network architecture, tom Truscott and Jim Ellis conceived the idea in 1979, and it was established in 1980. Users read and post messages to one or more categories, known as newsgroups, Usenet resembles a bulletin board system in many respects and is the precursor to Internet forums that are widely used today. Discussions are threaded, as with web forums and BBSs, though posts are stored on the server sequentially, the name comes from the term users network. One notable difference between a BBS or web forum and Usenet is the absence of a server and dedicated administrator. Usenet is distributed among a large, constantly changing conglomeration of servers that store, individual users may read messages from and post messages to a local server operated by a commercial usenet provider, their Internet service provider, university, employer, or their own server. Usenet has significant cultural importance in the world, having given rise to, or popularized, many widely recognized concepts and terms such as FAQ, flame. The name Usenet emphasized its creators hope that the USENIX organization would take a role in its operation. The articles that users post to Usenet are organized into topical categories called newsgroups, for instance, sci. math and sci. physics are within the sci. * hierarchy, for science. Or, talk. origins and talk. atheism are in the talk. * hierarchy, when a user subscribes to a newsgroup, the news client software keeps track of which articles that user has read. In most newsgroups, the majority of the articles are responses to some other article, the set of articles that can be traced to one single non-reply article is called a thread. Most modern newsreaders display the articles arranged into threads and subthreads, when a user posts an article, it is initially only available on that users news server. Each news server talks to one or more servers and exchanges articles with them. In this fashion, the article is copied from server to server, the later peer-to-peer networks operate on a similar principle, but for Usenet it is normally the sender, rather than the receiver, who initiates transfers. Usenet was designed under conditions when networks were much slower and not always available, many sites on the original Usenet network would connect only once or twice a day to batch-transfer messages in and out. This is largely because the POTS network was used for transfers. The format and transmission of Usenet articles is similar to that of Internet e-mail messages, today, Usenet has diminished in importance with respect to Internet forums, blogs and mailing lists. The groups in alt. binaries are still used for data transfer
8.
Flaming (Internet)
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Flaming is a hostile and insulting interaction between persons over the internet, often involving the use of profanity. It can also be the swapping of insults back and forth or with many people teaming up on a single victim. Deliberate flaming, as opposed to flaming as a result of discussions, is carried out by individuals known as flamers. These users specialize in flaming and target specific aspects of a controversial conversation, in a modern Internet lexicon this term has been almost entirely superseded by trolling. Many social researchers have investigated flaming, coming up several different theories about the phenomenon. Jacob Borders, in discussing participants internal modeling of a discussion, says, Mental models are fuzzy, incomplete, furthermore, within a single individual, mental models change with time, even during the flow of a single conversation. The human mind assembles a few relationships to fit the context of a discussion, as debate shifts, so do the mental models. Even when only a topic is being discussed, each participant in a conversation employs a different mental model to interpret the subject. Fundamental assumptions differ but are never brought into the open, goals are different but left unstated. It is little wonder that compromise takes so long, and even when consensus is reached, the underlying assumptions may be fallacies that lead to laws and programs that fail. The human mind is not adapted to understanding correctly the consequences implied by a mental model, a mental model may be correct in structure and assumptions but, even so, the human mind—either individually or as a group consensus—is apt to draw the wrong implications for the future. Thus, online conversations often involve a variety of assumptions and motives unique to individual user. Without social context, users are often helpless to know the intentions of their counterparts, in addition to the problems of conflicting mental models often present in online discussions, the inherent lack of face-to-face communication online can encourage hostility. When social identity and ingroup status are salient, computer mediation can decrease flaming because individuals focus their attention on the context rather than themselves. Generally, then, a lack of social context creates an element of anonymity, Flaming incidents usually arise in response to a perception of one or more negotiation partners being unfair. Evidence of debates which resulted in insults being exchanged quickly back, arguments over the ratification of the United States Constitution were often socially and emotionally heated and intense, with many attacking one another through local newspapers. Such interactions have always been part of literary criticism, for example, Ralph Waldo Emersons contempt for Jane Austens works often extended to the author herself, with Emerson describing her as without genius, wit, or knowledge of the world. In turn, Thomas Carlyle called Emerson a hoary-headed toothless baboon, Internet flaming was mostly observed in Usenet newsgroups although it was known to occur in the WWIVnet and FidoNet computer networks as well
9.
Perfection
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Perfection is, broadly, a state of completeness and flawlessness. The term perfection is used to designate a range of diverse, if often kindred and these concepts have historically been addressed in a number of discrete disciplines, notably mathematics, physics, chemistry, ethics, aesthetics, ontology, and theology. The form of the word long fluctuated in various languages, the English language had the alternates, perfection and the Biblical perfectness. The word perfection derives from the Latin perfectio, and perfect — from perfectus and these expressions in turn come from perficio — to finish, to bring to an end. Perfectio thus literally means a finishing, and perfect — finished, the genealogy of the concept of perfection reaches back beyond Latin, to Greek. The Greek equivalent of the Latin perfectus was teleos, the latter Greek expression generally had concrete referents, such as a perfect physician or flutist, a perfect comedy or a perfect social system. Hence the Greek teleiotes was not yet so fraught with abstract, to avoid the latter associations, the Greek term has generally been translated as completeness rather than perfection. The oldest definition of perfection, fairly precise and distinguishing the shades of the concept, in Book Delta of the Metaphysics, he distinguishes three meanings of the term, or rather three shades of one meaning, but in any case three different concepts. Which is complete — which contains all the parts,2. Which is so good that nothing of the kind could be better,3, the first of these concepts is fairly well subsumed within the second. Between those two and the third, however, there arises a duality in concept, the variants on the concept of perfection would have been quite of a piece for two thousand years, had they not been confused with other, kindred concepts. The chief of these was the concept of that which is the best, in Latin, in antiquity, excellentia and perfectio made a pair, thus, for example, dignitaries were called perfectissime, just as they are now called excellency. Gottfried Wilhelm Leibniz, who thought much about perfection and held the world to be the best of possible worlds and this was formulated by Lucilio Vanini, who had a precursor in the 16th-century writer Joseph Juste Scaliger, and they in turn referred to the ancient philosopher Empedocles. Their argument, as given by the first two, was if the world were perfect, it could not improve and so would lack true perfection. To Empedocles, according to Vanini, perfection depends on incompleteness, since the latter possesses a potential for development, the paradox of perfection—that imperfection is perfect—applies not only to human affairs, but to technology. Thus, irregularity in semiconductor crystals is requisite for the production of semiconductors, the solution to the apparent paradox lies in a distinction between two concepts of perfection, that of regularity, and that of utility. Imperfection is perfect in technology, in the sense that irregularity is useful, perfect numbers have been distinguished ever since the ancient Greeks called them teleioi. There was, however, no consensus among the Greeks as to which numbers were perfect or why, a view that was shared by Plato held that 10 was a perfect number
10.
Programming language
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A programming language is a formal computer language designed to communicate instructions to a machine, particularly a computer. Programming languages can be used to programs to control the behavior of a machine or to express algorithms. From the early 1800s, programs were used to direct the behavior of such as Jacquard looms. Thousands of different programming languages have created, mainly in the computer field. Many programming languages require computation to be specified in an imperative form while other languages use forms of program specification such as the declarative form. The description of a language is usually split into the two components of syntax and semantics. Some languages are defined by a document while other languages have a dominant implementation that is treated as a reference. Some languages have both, with the language defined by a standard and extensions taken from the dominant implementation being common. A programming language is a notation for writing programs, which are specifications of a computation or algorithm, some, but not all, authors restrict the term programming language to those languages that can express all possible algorithms. For example, PostScript programs are created by another program to control a computer printer or display. More generally, a language may describe computation on some, possibly abstract. It is generally accepted that a specification for a programming language includes a description, possibly idealized. In most practical contexts, a programming language involves a computer, consequently, abstractions Programming languages usually contain abstractions for defining and manipulating data structures or controlling the flow of execution. Expressive power The theory of computation classifies languages by the computations they are capable of expressing, all Turing complete languages can implement the same set of algorithms. ANSI/ISO SQL-92 and Charity are examples of languages that are not Turing complete, markup languages like XML, HTML, or troff, which define structured data, are not usually considered programming languages. Programming languages may, however, share the syntax with markup languages if a computational semantics is defined, XSLT, for example, is a Turing complete XML dialect. Moreover, LaTeX, which is used for structuring documents. The term computer language is used interchangeably with programming language
11.
Version control
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Changes are usually identified by a number or letter code, termed the revision number, revision level, or simply revision. For example, an set of files is revision 1. When the first change is made, the set is revision 2. Each revision is associated with a timestamp and the making the change. Revisions can be compared, restored, and with some types of files, the numbering of book editions and of specification revisions are examples that date back to the print-only era. Today, the most capable revision control systems are used in software development. Software tools for revision control are essential for the organization of multi-developer projects, in computer software engineering, revision control is any kind of practice that tracks and provides control over changes to source code. Software developers sometimes use revision control software to maintain documentation and configuration files as well as source code, bugs or features of the software are often only present in certain versions. Therefore, for the purposes of locating and fixing bugs, it is important to be able to retrieve. At the simplest level, developers could simply retain multiple copies of the different versions of the program and this simple approach has been used on many large software projects. While this method can work, it is inefficient as many copies of the program have to be maintained. This requires a lot of self-discipline on the part of developers, consequently, systems to automate some or all of the revision control process have been developed. This ensures that the majority of management of version control steps is hidden behind the scenes, sophisticated revision control that tracks and accounts for ownership of changes to documents and code may be extremely helpful or even indispensable in such situations. Revision control may also track changes to files, such as those typically stored in /etc or /usr/local/etc on Unix systems. This gives system administrators another way to track changes made. Revision control manages changes to a set of data over time and these changes can be structured in various ways. Often the data is thought of as a collection of individual items, such as files or documents. This accords with intuitions about separate files, but causes problems when identity changes, such as during renaming, splitting, or merging of files
12.
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
13.
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
14.
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
15.
Pascal (programming language)
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A derivative known as Object Pascal designed for object-oriented programming was developed in 1985. Pascal, named in honor of the French mathematician, philosopher, before his work on Pascal, Wirth had developed Euler and ALGOL W and later went on to develop the Pascal-like languages Modula-2 and Oberon. Initially, Pascal was largely, but not exclusively, intended to teach structured programming. A generation of students used Pascal as a language in undergraduate courses. Variants of Pascal have also frequently used for everything from research projects to PC games. Newer Pascal compilers exist which are widely used, Pascal was the primary high-level language used for development in the Apple Lisa, and in the early years of the Macintosh. Parts of the original Macintosh operating system were hand-translated into Motorola 68000 assembly language from the Pascal sources, apollo Computer used Pascal as the systems programming language for its operating systems beginning in 1980. Object Pascal is still used for developing Windows applications but also has the ability to compile the same code to Mac, iOS. Another cross-platform version called Free Pascal, with the Lazarus IDE, is popular with Linux users since it also offers write once, codeTyphon is a Lazarus distribution with more preinstalled packages and cross compilers. Wirths intention was to create an efficient language based on structured programming, important features included for this were records, enumerations, subranges, dynamically allocated variables with associated pointers, and sets. To make this possible and meaningful, Pascal has a strong typing on all objects, similar mechanisms are standard in many programming languages today. This enables a very simple and coherent syntax where a program is syntactically nearly identical to a single procedure or function. The first Pascal compiler was designed in Zürich for the CDC6000 series mainframe computer family, Niklaus Wirth reports that a first attempt to implement it in Fortran in 1969 was unsuccessful due to Fortrans inadequacy to express complex data structures. The second attempt was implemented in a C-like language and then translated by hand to Pascal itself for boot-strapping, the GNU Pascal compiler is one notable exception, being written in C. The first successful port of the CDC Pascal compiler to another mainframe was completed by Welsh, the target was the ICL1900 series. This compiler, in turn, was the parent of the Pascal compiler for the Information Computer Systems Multum minicomputer and it is thought that Multum Pascal, which was completed in the summer of 1973, may have been the first 16-bit implementation. A completely new compiler was completed by Welsh et al. at QUB in 1977 and it offered a source-language diagnostic feature that was implemented by Findlay and Watt at Glasgow University. This implementation was ported in 1980 to the ICL2900 series by a team based at Southampton University, the first Pascal compiler written in North America was constructed at the University of Illinois under Donald B
16.
Fortran
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Fortran is a general-purpose, imperative programming language that is especially suited to numeric computation and scientific computing. It is a language for high-performance computing and is used for programs that benchmark. Fortran encompasses a lineage of versions, each of which evolved to add extensions to the language while usually retaining compatibility with prior versions, the names of earlier versions of the language through FORTRAN77 were conventionally spelled in all-capitals. The capitalization has been dropped in referring to newer versions beginning with Fortran 90, the official language standards now refer to the language as Fortran rather than all-caps FORTRAN. In late 1953, John W. Backus submitted a proposal to his superiors at IBM to develop a practical alternative to assembly language for programming their IBM704 mainframe computer. Backus historic FORTRAN team consisted of programmers Richard Goldberg, Sheldon F. Best, Harlan Herrick, Peter Sheridan, Roy Nutt, Robert Nelson, Irving Ziller, Lois Haibt, and David Sayre. Its concepts included easier entry of equations into a computer, a developed by J. Halcombe Laning and demonstrated in the Laning. A draft specification for The IBM Mathematical Formula Translating System was completed by mid-1954, the first manual for FORTRAN appeared in October 1956, with the first FORTRAN compiler delivered in April 1957. John Backus said during a 1979 interview with Think, the IBM employee magazine, the language was widely adopted by scientists for writing numerically intensive programs, which encouraged compiler writers to produce compilers that could generate faster and more efficient code. The inclusion of a complex data type in the language made Fortran especially suited to technical applications such as electrical engineering. By 1960, versions of FORTRAN were available for the IBM709,650,1620, significantly, the increasing popularity of FORTRAN spurred competing computer manufacturers to provide FORTRAN compilers for their machines, so that by 1963 over 40 FORTRAN compilers existed. For these reasons, FORTRAN is considered to be the first widely used programming language supported across a variety of computer architectures, the arithmetic IF statement was similar to a three-way branch instruction on the IBM704. However, the 704 branch instructions all contained only one destination address, an optimizing compiler like FORTRAN would most likely select the more compact and usually faster Transfers instead of the Compare. Also the Compare considered −0 and +0 to be different values while the Transfer Zero, the FREQUENCY statement in FORTRAN was used originally to give branch probabilities for the three branch cases of the arithmetic IF statement. The Monte Carlo technique is documented in Backus et al, many years later, the FREQUENCY statement had no effect on the code, and was treated as a comment statement, since the compilers no longer did this kind of compile-time simulation. A similar fate has befallen compiler hints in other programming languages. The first FORTRAN compiler reported diagnostic information by halting the program when an error was found and that code could be looked up by the programmer in a error messages table in the operators manual, providing them with a brief description of the problem. Before the development of disk files, text editors and terminals, programs were most often entered on a keyboard onto 80-column punched cards
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Permutation
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These differ from combinations, which are selections of some members of a set where order is disregarded. For example, written as tuples, there are six permutations of the set, namely and these are all the possible orderings of this three element set. As another example, an anagram of a word, all of whose letters are different, is a permutation of its letters, in this example, the letters are already ordered in the original word and the anagram is a reordering of the letters. The study of permutations of finite sets is a topic in the field of combinatorics, Permutations occur, in more or less prominent ways, in almost every area of mathematics. For similar reasons permutations arise in the study of sorting algorithms in computer science, the number of permutations of n distinct objects is n factorial, usually written as n. which means the product of all positive integers less than or equal to n. In algebra and particularly in group theory, a permutation of a set S is defined as a bijection from S to itself and that is, it is a function from S to S for which every element occurs exactly once as an image value. This is related to the rearrangement of the elements of S in which each element s is replaced by the corresponding f, the collection of such permutations form a group called the symmetric group of S. The key to this structure is the fact that the composition of two permutations results in another rearrangement. Permutations may act on structured objects by rearranging their components, or by certain replacements of symbols, in elementary combinatorics, the k-permutations, or partial permutations, are the ordered arrangements of k distinct elements selected from a set. When k is equal to the size of the set, these are the permutations of the set, fabian Stedman in 1677 described factorials when explaining the number of permutations of bells in change ringing. Starting from two bells, first, two must be admitted to be varied in two ways which he illustrates by showing 12 and 21 and he then explains that with three bells there are three times two figures to be produced out of three which again is illustrated. His explanation involves cast away 3, and 1.2 will remain, cast away 2, and 1.3 will remain, cast away 1, and 2.3 will remain. He then moves on to four bells and repeats the casting away argument showing that there will be four different sets of three, effectively this is an recursive process. He continues with five bells using the casting method and tabulates the resulting 120 combinations. At this point he gives up and remarks, Now the nature of these methods is such, in modern mathematics there are many similar situations in which understanding a problem requires studying certain permutations related to it. There are two equivalent common ways of regarding permutations, sometimes called the active and passive forms, or in older terminology substitutions and permutations, which form is preferable depends on the type of questions being asked in a given discipline. The active way to regard permutations of a set S is to them as the bijections from S to itself. Thus, the permutations are thought of as functions which can be composed with each other, forming groups of permutations
18.
Decision tree
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A decision tree is a decision support tool that uses a tree-like graph or model of decisions and their possible consequences, including chance event outcomes, resource costs, and utility. It is one way to display an algorithm, Decision trees are commonly used in operations research, specifically in decision analysis, to help identify a strategy most likely to reach a goal, but are also a popular tool in machine learning. The paths from root to leaf represent classification rules, another use of decision trees is as a descriptive means for calculating conditional probabilities. Drawn from left to right, a tree has only burst nodes. Therefore, used manually, they can grow big and are then often hard to draw fully by hand. Traditionally, decision trees have been created manually — as the example shows — although increasingly. The decision tree can be linearized into decision rules, where the outcome is the contents of the node. In general, the rules have the form, if condition1 and condition2, Decision rules can be generated by constructing association rules with the target variable on the right. They can also denote temporal or causal relations, commonly a decision tree is drawn using flowchart symbols as it is easier for many to read and understand. Much of the information in a tree can be represented more compactly as an influence diagram, focusing attention on the issues. Decision trees can also be seen as models of induction rules from empirical data. An optimal decision tree is defined as a tree that accounts for most of the data. Several algorithms to generate such optimal trees have been devised, such as ID3/4/5, CLS, ASSISTANT, among decision support tools, decision trees have several advantages. Decision trees, Are simple to understand and interpret, people are able to understand decision tree models after a brief explanation. Have value even with little hard data, important insights can be generated based on experts describing a situation and their preferences for outcomes. Allow the addition of new possible scenarios Help determine worst, best, if a given result is provided by a model. Can be combined with other decision techniques, disadvantages of decision trees, For data including categorical variables with different number of levels, information gain in decision trees are biased in favor of those attributes with more levels. Calculations can get very complex particularly if many values are uncertain if many outcomes are linked
19.
Keyboard shortcut
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In computing, a keyboard shortcut is a series of one or several keys that invoke a software or operating system operation when triggered by the user. The meaning of term keyboard shortcut can vary depending on software manufacturer, keyboard shortcuts are generally used to expedite common operations by reducing input sequences to a few keystrokes, hence the term shortcut. To differentiate from general keyboard input, most keyboard shortcuts require the user to press, unmodified key presses are sometimes accepted when the keyboard is not used for general input - such as with graphics packages e. g. Adobe Photoshop or IBM Lotus Freelance Graphics. Other keyboard shortcuts use function keys that are dedicated for use in shortcuts, for simultaneous keyboard shortcuts, one usually first holds down the modifier key, then quickly presses and releases the regular key, and finally releases the modifier key. This distinction is important, as trying to all the keys simultaneously will frequently either miss some of the modifier keys. Sequential shortcuts usually involve pressing and releasing a dedicated key, such as the Esc key. Mnemonics are distinguishable from keyboard shortcuts, in most GUIs, a programs keyboard shortcuts are discoverable by browsing the programs menus – the shortcut is indicated next to the menu choice. There are keyboards that have the shortcuts for an application already marked on them. These keyboards are used for editing video, audio, or graphics. There are also stickers with shortcuts printed on them that can be applied to a regular keyboard, reference cards intended to be propped up in the users workspace also exist for many applications. This highlights a difference in philosophy regarding shortcuts, some systems, typically end-user-oriented systems such as Mac OS or Windows, consider standardized shortcuts essential to the environments ease of use. These systems usually limit a users ability to change shortcuts, possibly even requiring a separate or third-party utility to perform the task, other systems, typically Unix and related, consider shortcuts to be a users prerogative, and that they should be changeable to suit individual preference. For Microsoft Windows, multiple software programs exist like Hotkeycontrol which allow deeper customization of keyboard shortcuts performing advanced tasks, the motivations for customizing key bindings vary. Users new to a program or software environment may customize the new environments keybindings to be similar to another environment with which they are more familiar. More advanced users may customize key bindings to better suit their workflow, adding shortcuts for their commonly used actions, hardcore gamers often customize their key bindings in order to increase performance via faster reaction times. The original Macintosh User Interface Guidelines defined a set of keyboard shortcuts that would remain consistent across application programs and this provides a better user experience than the situation then prevalent of applications using the same keys for different functions. This could result in user errors if one program used ⌘ Command+D to mean Delete while another used it to Duplicate an item, Help Later environments such as Microsoft Windows retain some of these bindings, while adding their own from alternate standards like Common User Access. The simplest keyboard shortcuts consist of one key
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User interface
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The user interface, in the industrial design field of human–computer interaction, is the space where interactions between humans and machines occur. Examples of this concept of user interfaces include the interactive aspects of computer operating systems, hand tools, heavy machinery operator controls. The design considerations applicable when creating user interfaces are related to or involve such disciplines as ergonomics and psychology. Generally, the goal of user interface design is to produce a user interface makes it easy, efficient. This generally means that the needs to provide minimal input to achieve the desired output. Other terms for user interface are man–machine interface and when the machine in question is a computer human–computer interface, the user interface or human–machine interface is the part of the machine that handles the human–machine interaction. Membrane switches, rubber keypads and touchscreens are examples of the part of the Human Machine Interface which we can see. In complex systems, the interface is typically computerized. The term human–computer interface refers to this kind of system, in the context of computing the term typically extends as well to the software dedicated to control the physical elements used for human-computer interaction. The engineering of the interfaces is enhanced by considering ergonomics. The corresponding disciplines are human factors engineering and usability engineering, which is part of systems engineering, tools used for incorporating human factors in the interface design are developed based on knowledge of computer science, such as computer graphics, operating systems, programming languages. Nowadays, we use the graphical user interface for human–machine interface on computers. There is a difference between a user interface and an interface or a human–machine interface. A human-machine interface is typically local to one machine or piece of equipment, an operator interface is the interface method by which multiple equipment that are linked by a host control system is accessed or controlled. The system may expose several user interfaces to serve different kinds of users, for example, a computerized library database might provide two user interfaces, one for library patrons and the other for library personnel. The user interface of a system, a vehicle or an industrial installation is sometimes referred to as the human–machine interface. HMI is a modification of the original term MMI, in practice, the abbreviation MMI is still frequently used although some may claim that MMI stands for something different now. Another abbreviation is HCI, but is commonly used for human–computer interaction
21.
Random-access memory
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Random-access memory is a form of computer data storage which stores frequently used program instructions to increase the general speed of a system. A random-access memory device allows data items to be read or written in almost the same amount of time irrespective of the location of data inside the memory. RAM contains multiplexing and demultiplexing circuitry, to connect the lines to the addressed storage for reading or writing the entry. Usually more than one bit of storage is accessed by the same address, in todays technology, random-access memory takes the form of integrated circuits. RAM is normally associated with types of memory, where stored information is lost if power is removed. Other types of non-volatile memories exist that allow access for read operations. These include most types of ROM and a type of memory called NOR-Flash. Integrated-circuit RAM chips came into the market in the early 1970s, with the first commercially available DRAM chip, early computers used relays, mechanical counters or delay lines for main memory functions. Ultrasonic delay lines could only reproduce data in the order it was written, drum memory could be expanded at relatively low cost but efficient retrieval of memory items required knowledge of the physical layout of the drum to optimize speed. Latches built out of vacuum tube triodes, and later, out of transistors, were used for smaller and faster memories such as registers. Such registers were relatively large and too costly to use for large amounts of data, the first practical form of random-access memory was the Williams tube starting in 1947. It stored data as electrically charged spots on the face of a cathode ray tube, since the electron beam of the CRT could read and write the spots on the tube in any order, memory was random access. The capacity of the Williams tube was a few hundred to around a thousand bits, but it was smaller, faster. In fact, rather than the Williams tube memory being designed for the SSEM, magnetic-core memory was invented in 1947 and developed up until the mid-1970s. It became a form of random-access memory, relying on an array of magnetized rings. By changing the sense of each rings magnetization, data could be stored with one bit stored per ring, since every ring had a combination of address wires to select and read or write it, access to any memory location in any sequence was possible. Magnetic core memory was the form of memory system until displaced by solid-state memory in integrated circuits. Data was stored in the capacitance of each transistor, and had to be periodically refreshed every few milliseconds before the charge could leak away
22.
Lisp (programming language)
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Lisp is a family of computer programming languages with a long history and a distinctive, fully parenthesized prefix notation. Originally specified in 1958, Lisp is the second-oldest high-level programming language in use today. Only Fortran is older, by one year, Lisp has changed since its early days, and many dialects have existed over its history. Today, the best known general-purpose Lisp dialects are Common Lisp, Lisp was originally created as a practical mathematical notation for computer programs, influenced by the notation of Alonzo Churchs lambda calculus. It quickly became the programming language for artificial intelligence research. The name LISP derives from LISt Processor, linked lists are one of Lisps major data structures, and Lisp source code is made of lists. Thus, Lisp programs can manipulate source code as a data structure, the interchangeability of code and data gives Lisp its instantly recognizable syntax. All program code is written as s-expressions, or parenthesized lists, Lisp was invented by John McCarthy in 1958 while he was at the Massachusetts Institute of Technology. McCarthy published its design in a paper in Communications of the ACM in 1960, entitled Recursive Functions of Symbolic Expressions and Their Computation by Machine and he showed that with a few simple operators and a notation for functions, one can build a Turing-complete language for algorithms. Information Processing Language was the first AI language, from 1955 or 1956, and already included many of the concepts, such as list-processing and recursion, McCarthys original notation used bracketed M-expressions that would be translated into S-expressions. As an example, the M-expression car is equivalent to the S-expression, once Lisp was implemented, programmers rapidly chose to use S-expressions, and M-expressions were abandoned. M-expressions surfaced again with short-lived attempts of MLISP by Horace Enea, Lisp was first implemented by Steve Russell on an IBM704 computer. Russell had read McCarthys paper and realized that the Lisp eval function could be implemented in machine code, the result was a working Lisp interpreter which could be used to run Lisp programs, or more properly, evaluate Lisp expressions. Two assembly language macros for the IBM704 became the operations for decomposing lists, car. From the context, it is clear that the register is used here to mean memory register. Lisp dialects still use car and cdr for the operations that return the first item in a list, the first complete Lisp compiler, written in Lisp, was implemented in 1962 by Tim Hart and Mike Levin at MIT. This compiler introduced the Lisp model of incremental compilation, in which compiled and interpreted functions can intermix freely, the language used in Hart and Levins memo is much closer to modern Lisp style than McCarthys earlier code. Lisp was a system to implement with the compiler techniques
23.
Graphical user interface
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GUIs were introduced in reaction to the perceived steep learning curve of command-line interfaces, which require commands to be typed on a computer keyboard. The actions in a GUI are usually performed through direct manipulation of the graphical elements, beyond computers, GUIs are used in many handheld mobile devices such as MP3 players, portable media players, gaming devices, smartphones and smaller household, office and industrial controls. Designing the visual composition and temporal behavior of a GUI is an important part of application programming in the area of human–computer interaction. Its goal is to enhance the efficiency and ease of use for the logical design of a stored program. Methods of user-centered design are used to ensure that the language introduced in the design is well-tailored to the tasks. The visible graphical interface features of an application are sometimes referred to as chrome or GUI, typically, users interact with information by manipulating visual widgets that allow for interactions appropriate to the kind of data they hold. The widgets of an interface are selected to support the actions necessary to achieve the goals of users. A model–view–controller allows a structure in which the interface is independent from and indirectly linked to application functions. This allows users to select or design a different skin at will, good user interface design relates to users more, and to system architecture less. Large widgets, such as windows, usually provide a frame or container for the main presentation content such as a web page, smaller ones usually act as a user-input tool. A GUI may be designed for the requirements of a market as application-specific graphical user interfaces. By the 1990s, cell phones and handheld game systems also employed application specific touchscreen GUIs, newer automobiles use GUIs in their navigation systems and multimedia centers, or navigation multimedia center combinations. Sample graphical desktop environments A GUI uses a combination of technologies and devices to provide a platform that users can interact with, a series of elements conforming a visual language have evolved to represent information stored in computers. This makes it easier for people with few computer skills to work with, the most common combination of such elements in GUIs is the windows, icons, menus, pointer paradigm, especially in personal computers. The WIMP style of interaction uses a virtual device to represent the position of a pointing device, most often a mouse. Available commands are compiled together in menus, and actions are performed making gestures with the pointing device, a window manager facilitates the interactions between windows, applications, and the windowing system. The windowing system handles hardware devices such as pointing devices, graphics hardware, window managers and other software combine to simulate the desktop environment with varying degrees of realism. Smaller mobile devices such as personal assistants and smartphones typically use the WIMP elements with different unifying metaphors, due to constraints in space
24.
Typeface
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In metal typesetting, a font is a particular size, weight and style of a typeface. Each font was a set of type, one piece for each glyph. In modern usage, with the advent of digital typography, font is frequently synonymous with typeface, in particular, the use of vector or outline fonts means that different sizes of a typeface can be dynamically generated from one design. The word font derives from Middle French fonte melted, a casting, the term refers to the process of casting metal type at a type foundry. In a manual printing house the word font would refer to a set of metal type that would be used to typeset an entire page. Unlike a digital typeface it would not include a definition of each character. A font when bought new would often be sold as 12pt 14A 34a, meaning that it would be a size 12-point font containing 14 uppercase As, given the name upper and lowercase because of which case the metal type was located in, otherwise known as majuscule and minuscule. The rest of the characters would be provided in quantities appropriate for the distribution of letters in that language. Some metal type characters required in typesetting, such as dashes, spaces and line-height spacers, were not part of a specific font, line spacing is still often called leading, because the strips used for line spacing were made of lead. In the 1880s–90s, hot lead typesetting was invented, in which type was cast as it was set, either piece by piece or in entire lines of type at one time. In European alphabetic scripts, i. e. Latin, Cyrillic and Greek, the main properties are the stroke width, called weight, the style or angle. The regular or standard font is sometimes labeled roman, both to distinguish it from bold or thin and from italic or oblique. The keyword for the default, regular case is often omitted for variants and never repeated, otherwise it would be Bulmer regular italic, Bulmer bold regular, Roman can also refer to the language coverage of a font, acting as a shorthand for Western European. Different fonts of the same typeface may be used in the work for various degrees of readability and emphasis. The weight of a font is the thickness of the character outlines relative to their height. A typeface may come in fonts of many weights, from ultra-light to extra-bold or black, four to six weights are not unusual, many typefaces for office, web and non-professional use come with just a normal and a bold weight which are linked together. If no bold weight is provided, many renderers support faking a bolder font by rendering the outline a second time at an offset, the base weight differs among typefaces, that means one normal font may appear bolder than some other normal font. For example, fonts intended to be used in posters are often quite bold by default while fonts for long runs of text are rather light, therefore, weight designations in font names may differ in regard to the actual absolute stroke weight or density of glyphs in the font
25.
Text-based user interface
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Text-based user interface, also called textual user interface or terminal user interface, is a retronym coined sometime after the invention of graphical user interfaces. TUIs display computer graphics in text mode, an advanced TUI may, like GUIs, use the entire screen area and accept mouse and other inputs. From text applications point of view, a screen can belong to one of three types, A genuine text mode display, controlled by a video adapter or the central processor itself. This is a condition for a locally running application on various types of personal computers. If not deterred by the system, a smart program may exploit the full power of a hardware text mode. Examples are xterm for X Window System and win32 console for Microsoft Windows and this usually supports programs which expect a real text mode display, but may run considerably slower. Certain functions of a text mode, such as an own font uploading. The communication capabilities usually become reduced to a line or its emulation, possibly with few ioctls as an out-of-band channel in such cases as Telnet. This is the worst case, because software restrictions hinder the use of capabilities of a display device. Under Linux and other Unix-like systems, a program easily accommodates to any of the three cases because the same interface controls the display and keyboard, also, specialized programming libraries help to output the text in a way appropriate to the given display device and interface to it. See below for a comparison to Windows, american National Standards Institute standard ANSI X3.64 defines a standard set of escape sequences that can be used to drive terminals to create TUIs. Escape sequences may be supported for all three mentioned in the above section, allowing random cursor movements and color changes. However, not all follow this standard, and many non-compatible. However, programmers soon learned that writing data directly to the buffer was far faster and simpler to program. This change in programming resulted in many DOS TUI programs. The win32 console environment is notorious for its emulation of certain EGA/VGA text mode features, particularly a random access to the text buffer, even if the application runs in a window. On the other hand, programs running under Windows have much control of the display and keyboard than Linux and DOS programs can have. Most often those used a blue background for the main screen, with white or yellow characters
26.
Lisp machine
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Lisp machines are general-purpose computers designed to efficiently run Lisp as their main software and programming language, usually via hardware support. They are an example of a language computer architecture, and in a sense. Several firms built and sold Lisp machines in the 1980s, Symbolics, Lisp Machines Incorporated, Texas Instruments, the operating systems were written in Lisp Machine Lisp, Interlisp, and later partly in Common Lisp. Artificial intelligence computer programs of the 1960s and 1970s intrinsically required what was considered a huge amount of computer power, as measured in processor time. At first, the cost of computer hardware meant that it had to be shared among many users. To keep the system simple, these machines would not be shared. The machine also did incremental garbage collection, Lisp Machines ran the tests in parallel with the more conventional single instruction additions. If the simultaneous tests failed, then the result was discarded and recomputed and this simultaneous checking approach was used as well in testing the bounds of arrays when referenced, and other memory management necessities. Type checking was further improved and automated when the conventional byte word of 32-bits was lengthened to 36-bits for Symbolics 3600-model Lisp machines, the first machine was called the CONS machine. Often it was referred to as the Knight machine, perhaps since Knight wrote his masters thesis on the subject. It was subsequently improved into a version called CADR which was based on essentially the same architecture and it was so well received at an AI conference held at MIT in 1978 that Defense Advanced Research Projects Agency began funding its development. In a counter-intuitive move for an AI Lab hacker, Greenblatt acquiesced, hoping perhaps that he could recreate the informal and these ideas and goals were considerably different from those of Noftsker. The two negotiated at length, but neither would compromise, the ensuing discussions of the choice divided the lab into two factions. In February 1979, matters came to a head and it was at this juncture that Symbolics, Noftskers enterprise, slowly came together. While Noftsker was paying his staff a salary, he had no building or any equipment for the hackers to work on. He bargained with Patrick Winston that, in exchange for allowing Symbolics’ staff to keep working out of MIT, Greenblatt had decided to start his own rival Lisp machine firm, but he had done nothing. Jacobson pulled together business plans, a board, a partner for Greenblatt, the newfound firm was named LISP Machine, Inc. and was funded by CDC orders, via Jacobson. Around this time Symbolics began operating and it had been hindered by Noftskers promise to give Greenblatt a year’s head start, and by severe delays in procuring venture capital
27.
X Window System
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The X Window System is a windowing system for bitmap displays, common on UNIX-like computer operating systems. X provides the framework for a GUI environment, drawing and moving windows on the display device and interacting with a mouse. X does not mandate the user interface – this is handled by individual programs, as such, the visual styling of X-based environments varies greatly, different programs may present radically different interfaces. X originated at the Massachusetts Institute of Technology in 1984, the protocol has been version 11 since September 1987. The X. Org Foundation leads the X project, with the current reference implementation, X. Org Server, available as free and open source software under the MIT License, X is an architecture-independent system for remote graphical user interfaces and input device capabilities. Each person using a terminal has the ability to interact with the display with any type of user input device. X provides the framework, or primitives, for building such GUI environments, drawing and moving windows on the display and interacting with a mouse. X does not mandate the user interface, individual client programs handle this, programs may use Xs graphical abilities with no user interface. As such, the styling of X-based environments varies greatly. Unlike most earlier display protocols, X was specifically designed to be used over network connections rather than on an integral or attached display device. X features network transparency, which means an X program running on a computer somewhere on a network can display its user interface on an X server running on other computer on the network. The fact that the server is applied to the software in front of the user is often surprising to users accustomed to their programs being clients to services on remote computers. Xs network protocol is based on X command primitives and this approach allows both 2D and 3D operations by an X client application which might be running on a different computer to still be fully accelerated on the X servers display. X provides no support for audio, several projects exist to fill this niche. X uses a model, an X server communicates with various client programs. The server accepts requests for graphical output and sends back user input, a client and server can even communicate securely over the Internet by tunneling the connection over an encrypted network session. An X client itself may emulate an X server by providing services to other clients. This is known as X nesting, open-source clients such as Xnest and Xephyr support such X nesting
28.
Hypertext
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Hypertext documents are interconnected by hyperlinks, which are typically activated by a mouse click, keypress sequence or by touching the screen. Apart from text, the hypertext is also sometimes used to describe tables, images. Hypertext is one of the key underlying concepts of the World Wide Web, as implemented on the Web, hypertext enables the easy-to-use publication of information over the Internet. The English prefix hyper- comes from the Greek prefix ὑπερ- and means over or beyond and it signifies the overcoming of the previous linear constraints of written text. The term hypertext is often used where the term hypermedia might seem appropriate, instead they use the strange term interactive multimedia, this is four syllables longer, and does not express the idea of extending hypertext. Hypertext documents can either be static or dynamic, static hypertext can be used to cross-reference collections of data in documents, software applications, or books on CDs. A well-constructed system can also incorporate other user-interface conventions, such as menus, links used in a hypertext document usually replace the current piece of hypertext with the destination document. A lesser known feature is StretchText, which expands or contracts the content in place, Hypertext can be used to support very complex and dynamic systems of linking and cross-referencing. The most famous implementation of hypertext is the World Wide Web, written in the months of 1990. In 1941, Jorge Luis Borges published The Garden of Forking Paths, in 1945, Vannevar Bush wrote an article in The Atlantic Monthly called As We May Think, about a futuristic proto-hypertext device he called a Memex. The coded symbols would enable the Memex to index, search, in 1963, Ted Nelson coined the terms hypertext and hypermedia as part of a model he developed for creating and using linked content. He later worked with Andries van Dam to develop the Hypertext Editing System in 1967 at Brown University, in December of that year, Engelbart demonstrated a hypertext interface to the public for the first time, in what has come to be known as The Mother of All Demos. The first hypermedia application is considered to be the Aspen Movie Map. The Movie Map allowed users to choose which way they wished to drive in a virtual cityscape. In 1980, Tim Berners-Lee created ENQUIRE, an early hypertext database system somewhat like a wiki but without hypertext punctuation, which was not invented until 1987. The early 1980s also saw a number of experimental hyperediting functions in word processors and hypermedia programs, many of whose features, guide, the first significant hypertext system for personal computers, was developed by Peter J. Brown at UKC in 1982. Sponsored by the founder of IBM, Thomas J, in 1983, Ben Shneiderman at the University of Maryland Human - Computer Interaction Lab led a group that developed the HyperTies system that was commercialized by Cognetics Corporation. Hyperties was used to create the July 1988 issue of the Communications of the ACM as a hypertext document, in August 1987, Apple Computer released HyperCard for the Macintosh line at the MacWorld convention
29.
Mode (computer interface)
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An interface that uses no modes is known as a modeless interface. Modeless interfaces avoid mode errors by making it impossible for the user to commit them, in Raskins sense and according to his definition, an interface is not modal as long as the user is fully aware of its current state. Raskin refers to this as locus of attention, if the users locus of attention changes to a different area, the state of the interface may then represent a mode since the user is no longer aware of it. Vi – has one mode for inserting text, and a mode for entering commands. There is also an ex mode for issuing more complex commands, under normal circumstances, the editor automatically returns to the previous mode after a command has been issued, however, it is possible to permanently move into this mode using Shift-Q. Emacs – has the concept of keys, which trigger a modal state by pressing the control key plus a letter key. Emacs then waits for additional keypresses that complete a keybinding and this differs from vi in that the mode always ends as soon as the command is called. Emacs also has major and minor modes that change the available commands. Modes are written in Emacs Lisp, and all modes may not be included with all versions, cisco IOS – certain commands are executed in a command mode. Tools chosen from a palette in photo-editing and drawing applications are examples of a modal interface, some advanced image editors have a feature where the same tools can be accessed nonmodally by a keypress, and remain active as long as the key is held down. Releasing the key returns the interface to the modal tool activated by the palette, video games can use game modes as a mechanic to enhance gameplay. Modal windows block all workflow in the program until the modal window is closed. A mode error can be startling and disorienting as the user copes with the sudden violation of his or her user expectations. Problems occur if a change in the system state happens unnoticed, another typical problem is a sudden change of state that interrupts a users activity, such as focus stealing. In such a situation it can happen that the user does some operations with the old state in mind. A very frustrating type of modality is created by a mode where the user does not find a way out, in other words, the most common source of mode errors may be the Caps Lock key. Other common modes available in PC keyboards are Insert and the other keys, Num lock. Dead keys for diacritics also create a mode, at least if they dont provide visual feedback that the next typed character will be modified
30.
Event (computing)
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In computing, an event is an action or occurrence recognized by software that may be handled by the software. Computer events can be generated or triggered by the system, by the user or in other ways, typically, events are handled synchronously with the program flow, that is, the software may have one or more dedicated places where events are handled, frequently an event loop. A source of events includes the user, who may interact with the software by way of, for example, another source is a hardware device such as a timer. Software can also trigger its own set of events into the event loop, software that changes its behavior in response to events is said to be event-driven, often with the goal of being interactive. Event driven systems are used when there is some asynchronous external activity that needs to be handled by a program, for example. An event driven system typically runs an event loop, that keeps waiting for such activities, when one of these occurs, it collects data about the event and dispatches the event to the event handler software that will deal with it. A program can choose to ignore events, and there may be libraries to dispatch an event to multiple handlers that may be programmed to listen for a particular event. Events are typically used in interfaces, where actions in the outside world are handled by the program as a series of events. Programs written for many windowing environments consist predominantly of event handlers, events can also be used at instruction set level, where they complement interrupts. Compared to interrupts, events are handled synchronously, the program explicitly waits for an event to be serviced. A common variant in object-oriented programming is the event model. C# uses events as special delegates that can only be fired by the class that declares it and this allows for better abstraction, for example, In computer programming, an event handler is a callback subroutine that handles inputs received in a program. Each event is a piece of information from the underlying framework. GUI events include key presses, mouse movement, action selections, on a lower level, events can represent availability of new data for reading a file or network stream. Event handlers are a concept in event-driven programming. The events are created by the based on interpreting lower-level inputs. For example, mouse movements and clicks are interpreted as menu selections, the events initially originate from actions on the operating system level, such as interrupts generated by hardware devices, software interrupt instructions, or state changes in polling. On this level, interrupt handlers and signal handlers correspond to event handlers, created events are first processed by an event dispatcher within the framework
31.
Command-line interface
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A program which handles the interface is called a command language interpreter or shell. The interface is implemented with a command line shell, which is a program that accepts commands as text input. Command-line interfaces to computer operating systems are widely used by casual computer users. Alternatives to the line include, but are not limited to text user interface menus, keyboard shortcuts. Examples of this include the Windows versions 1,2,3,3.1, and 3.11, DosShell, and Mouse Systems PowerPanel. Command-line interfaces are preferred by more advanced computer users, as they often provide a more concise. Programs with command-line interfaces are generally easier to automate via scripting, a program that implements such a text interface is often called a command-line interpreter, command processor or shell. Under most operating systems, it is possible to replace the shell program with alternatives, examples include 4DOS for DOS, 4OS2 for OS/2. For example, the default Windows GUI is a program named EXPLORER. EXE. These programs are shells, but not CLIs, application programs may also have command line interfaces. When a program is launched from an OS command line shell, interactive command line sessions, After launch, a program may provide an operator with an independent means to enter commands in the form of text. OS inter-process communication, Most operating systems support means of inter-process communication, Command lines from client processes may be redirected to a CLI program by one of these methods. Some applications support only a CLI, presenting a CLI prompt to the user, Some examples of CLI-only applications are, DEBUG Diskpart Ed Edlin Fdisk Ping Some computer programs support both a CLI and a GUI. In some cases, a GUI is simply a wrapper around a separate CLI executable file, in other cases, a program may provide a CLI as an optional alternative to its GUI. CLIs and GUIs often support different functionality, for example, all features of MATLAB, a numerical analysis computer program, are available via the CLI, whereas the MATLAB GUI exposes only a subset of features. The early Sierra games, like the first three Kings Quest games, used commands from a command line to move the character around in the graphic window. Early computer systems often used teleprinter machines as the means of interaction with a human operator, the computer became one end of the human-to-human teleprinter model. So instead of a human communicating with another human over a teleprinter, in time, the actual mechanical teleprinter was replaced by a glass tty, and then by a smart terminal
32.
Autocomplete
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Autocomplete, or word completion, is a feature in which an application predicts the rest of a word a user is typing. In graphical user interfaces, users can press the tab key to accept a suggestion or the down arrow key to accept one of several. Autocomplete speeds up human-computer interactions when it predicts the word a user intends to enter after only a few characters have been typed into a text input field. It works best in domains with a number of possible words. Many autocomplete algorithms learn new words after the user has written them a few times, and can suggest alternatives based on the learned habits of the individual user. The need to speed is noted by the fact that people who use speech generating devices generally produce speech at a rate that is less than 10% as fast as people who use oral speech. But the function is very useful for anybody who writes text. Autocomplete or word completion works so that when the writer writes the first letter or letters of a word, if the word he intends to write is included in the list he can select it, for example by using the number keys. If the word that the user wants is not predicted, the writer must enter the letter of the word. At this time, the choice is altered so that the words provided begin with the same letters as those that have been selected. When the word that the user wants appears it is selected, in another form of word prediction, words most likely to follow the just written one are predicted, based on recent word pairs used. Word prediction uses language modeling, where within a set vocabulary the words are most likely to occur are calculated. Along with language modeling, basic word prediction on AAC devices is often coupled with a recency model, Word prediction software often also allows the user to enter their own words into the word prediction dictionaries either directly, or by learning words that have been written. There are standalone tools that add functionality to existing applications. These programs monitor user keystrokes and suggests a list of words based on first typed letter, letMeType, freeware, is no longer developed, the author has published the source code and allows anybody to continue development. Typingaid, also freeware, is actively developed, Intellicomplete, both a freeware and payware version, works only in certain programs which hook into the intellicomplete server program. Many Autocomplete programs can also be used to create a Shorthand list and this can also quietly fix simple typing errors, such as turning teh into the. Several Autocomplete programs, standalone or integrated in text editors, based on word lists, the main advantage of context completion is the ability to predict anticipated words more precisely and even with no initial letters
33.
Esc key
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On computer keyboards, the Esc key is a key used to generate the escape character. It is now placed at the top left corner of the keyboard. The keyboard symbol for the ESC key is standardized in ISO/IEC 9995-7 as symbol 29 and this symbol is encoded in Unicode as U+238B broken circle with northwest arrow. The Escape keys creation is credited to Bob Bemer, a programmer who worked for IBM. He created the key in 1960 to allow programmers working with machines to switch from one type of code to another. Much later printers and computer terminals that would use escape sequences often would take more than one following byte as part of a special sequence and this key combination still works as of Windows 10. Microsoft Windows makes use of Esc for many key shortcuts, many of these shortcuts have been present since Windows 3.0, through Windows XP, Windows Vista, Windows 7, Windows 8, and Windows 10. In OS X, Esc usually closes or cancels a dialog box or sheet, the ⌘ Command+⌥ Option+⎋ Esc combination opens the Force Quit dialog box, allowing users to end non-responsive programs. Another use for the Esc key, in combination with the Command key, is switching to Front Row, if installed. In most computer games, the key is used as a pause button and/or as a way to bring up the in-game menu. In the vi family of text editors, escape is used to switch modes and this usage is due to escape being conveniently placed in what is now the tab position on the ADM-3A terminal keyboard used to develop vi, though it is now inconveniently placed. Although such devices are long out of use, standard processing of ANSI Escape sequences very similar to 1970s VT100, is implemented in both ANSI
34.
Teletype Corporation
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Because of the nature of its business, as stated in the corporate charter, Teletype Corporation was allowed a unique mode of operation within Western Electric. It was organized as an entity, and contained all the elements necessary for a separate corporation. Teletypes charter permitted the sale of equipment to customers outside the AT&T Bell System, the primary customer outside of the Bell System was the United States Government. The Teletype Corporation continued in this manner until January 8,1982, the date of settlement of United States v. AT&T, at that time, Western Electric was fully absorbed into AT&T as AT&T Technologies, and the Teletype Corporation became AT&T Teletype. The last vestiges of what had been the Teletype Corporation ceased in 1990, one of the three Teletype manufacturing buildings in Skokie remains in use as a parking garage for a shopping center. Every other floor of the building has been removed, the other two buildings were demolished. The Teletype Corporation had its roots in the Morkrum Company, in 1902, electrical engineer Frank Pearne approached Joy Morton, head of Morton Salt, seeking a sponsor for Pearnes research into the practicalities of developing a printing telegraph system. Krum was interested in helping Pearne, so space was set up in a laboratory in the attic of Western Cold Storage, Frank Pearne lost interest in the project after a year, and left to get involved in teaching. Krum was prepared to continue Pearne’s work, and in August 1903 a patent was filed for a page printer. In 1904, Krum filed a patent for a type wheel printing telegraph machine which was issued in August 1907, in 1906, the Morkrum Company was formed, with the company name combining the Morton and Krum names and reflecting the financial assistance provided by Joy Morton. This is the time when Charles Krums son, Howard Krum and it was Howard who developed and patented the start-stop synchronizing method for code telegraph systems, which made possible the practical teleprinter. In 1908, a working teleprinter was produced, called the Morkrum Printing Telegraph, in 1925, the Morkrum Company and the Kleinschmidt Electric Company merged to form the Morkrum-Kleinschmidt Company. In December 1928, the changed its name to the less cumbersome Teletype Corporation. In 1930, the Teletype Corporation was purchased by the American Telephone and Telegraph Company for $30,000,000 in stock, while other principals in the Teletype Corporation retired, Howard Krum stayed on as a consultant. Morkrum Printing Telegraph – This was the first mechanically successful teleprinter, a Blue Code Version was used in 1910 as a part of the first commercial teleprinter circuit that ran on Postal Telegraph Company lines between Boston and New York City. In 1914, a Green Code Version was installed using Western Union Telegraph Company lines for the Associated Press and was used to distribute news to competing newspapers in New York City. The Model 11 was a Tape Printer which used gummed paper tape that could be pasted onto a telegram blank and this was the first teleprinter to successfully operate from an airplane. Morkrum Model GPE Perforator – The Morkrum Company Model GPE Green Code Perforator was designed about 1913 and this equipment continued to be produced for the next 50 years
35.
Backronym
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A backronym or bacronym is a specially constructed phrase that is supposed to be the source of a word that is, or is claimed to be, an acronym. Backronyms may be invented with serious or humorous intent, or may be a type of false or folk etymology, the word is a combination of backward and acronym, and has been defined as a reverse acronym. Its earliest known citation in print is as bacronym in the November 1983 edition of the Washington Post monthly neologism contest. The newspaper quoted winning reader Meredith G. Williams of Potomac, Maryland, defining it as the same as an acronym, except that the words were chosen to fit the letters. An acronym is a derived from the initial letters of the words of a phrase, For example. By contrast, a backronym is constructed by creating a new phrase to fit an existing word, name. Backronyms are also used for comedic effect, as exemplified by NASAs C. O. L. B. E. R. T. NASA named its ISS treadmill the Combined Operational Load-Bearing External Resistance Treadmill after Stephen Colbert, the backronym was a lighthearted compromise in recognition of the comedians ability to sway NASAs online vote for the naming of an ISS module. Backronyms can be constructed for educational purposes, for example to form mnemonics, an example of such a mnemonic is the Apgar score, used to assess the health of newborn babies. Alcoholics Anonymous and other 12-step programs use backronyms as teaching tools, similar to such as one day at a time, or Let go, let God. For example, a slip may be expanded as Sobriety Losing Its Priority, backronyms are also created as jokes or as slogans, often expressing consumer loyalties or frustration. For example, the name of the restaurant chain Arbys is a play on the letters RB, referring to the companys founders, an advertising campaign in the 1980s created a backronym with the slogan America’s Roast Beef, Yes Sir. Many companies or products have spawned multiple humorous backronyms, with positive connotations asserted by supporters or negative ones by detractors. For example, the car company Ford was said to stand for First On Race Day, by aficionados, similar backronyms have been directed against many other automakers, such as Fix It Again Tony for Fiat. Backronyms have also coined by military personnel during wartime. The backronym for Spam, Something Posing As Meat, was said to have originated from jaundiced soldiers who were sick of eating canned meat. The British contribution to the 2003 invasion of Iraq was code-named Operation Telic, backronyms are sometimes created to name laws or programs. Commentators have noted a trend among US lawmakers to devise names that form a desired acronym
36.
Space-cadet keyboard
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It was inspired by the Knight keyboard, which was developed for the Knight TV system, used with MITs Incompatible Timesharing System. The Symbolics-labeled version shown here was used with the LM-2. The space-cadet keyboard was equipped with seven modifier keys, four keys for bucky bits, meta had been introduced on the earlier Knight keyboard, while Hyper and Super were introduced by this keyboard. Many keys had three symbols on them, accessible via the keys, a letter and a symbol on the top. For example, the L key had an L and an arrow on the top. On this keyboard, it is possible to type over 8,000 different characters and this allowed the user to type very complicated mathematical text, and also to have thousands of single-character commands at their disposal. Many users were willing to memorise the command meanings of many characters if it reduced typing time. This attitude shaped the interface of Emacs, compare the use of the Esc key in vi, due to the convenient position of the key on the ADM-3A terminal. Other users, however, thought that so many bucky bits was overkill and this keyboard included a Macro key which had limited application support. It also included four Roman Numeral keys which allowed for interaction with lists of four or fewer choices. Space-cadet Keyboard and Lisp Machine Keyboards
37.
Text mode
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Text mode is a computer display mode in which content is internally represented on a computer screen in terms of characters rather than individual pixels. Typically, the screen consists of a rectangular grid of character cells. Text mode is contrasted to all points addressable mode or other kinds of computer graphics modes, text mode applications communicate with the user with command-line interfaces and text user interfaces. A typical example is the IBM code page 437 character set and this was an analogy of early mechanical printers which had fixed pitch. This way, the output seen on the screen could be sent directly to the printer maintaining exactly the same format, depending on the environment, the screen buffer can be directly addressable. Programs that display output on remote video terminals must issue special control sequences to manipulate the screen buffer, the most popular standards for such control sequences are ANSI and VT100. Text mode video rendering came to prominence in the early 1970s, the advantages of text modes as compared to graphics modes include lower memory consumption and faster screen manipulation. Early framebuffers were standalone devices which cost thousands of dollars, in addition to the expense of the advanced high-resolution displays to which they were connected. For applications that required simple line graphics but for which the expense of a framebuffer could not be justified, but there were many computer applications for which all that was required was the ability to render ordinary text in a quick and cost-effective fashion to a cathode ray tube. Text mode avoids the problem of memory by having dedicated display hardware re-render each line of text from characters into pixels with each scan of the screen by the cathode ray. In turn, the hardware needs only enough memory to store the pixels equivalent to one line of text at a time. For example, a screen buffer sufficient to hold a standard grid of 80 by 25 characters requires at least 2,000 bytes. S. dollars, another advantage of text mode is that it has relatively low bandwidth requirements in remote terminal use. Text mode rendering with user-defined characters has also been useful for 2D computer, a video controller implementing a text mode usually uses two distinct areas of memory. Character memory or a table contains a raster font in use. Display matrix tracks which character is in each cell, in the simple case the display matrix can be just a matrix of code points, but it usually stores for each character position not only a code, but also attributes. The video controller has two registers, scan line counter and dot counter, serving as coordinates in the dot matrix. Each of them must be divided by corresponding glyph size to obtain an index in the display matrix, the character memory resides in a read-only memory in some systems. Other systems allow the use of RAM for this purpose, making it possible to redefine the typeface, in some historical graphics chips, including the TMS9918, the MOS Technology VIC, and the Game Boy graphics hardware, this was actually the canonical way of doing pixel graphics
38.
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
39.
Unix-like
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A Unix-like operating system is one that behaves in a manner similar to a Unix system, while not necessarily conforming to or being certified to any version of the Single UNIX Specification. A Unix-like application is one that behaves like the corresponding Unix command or shell, there is no standard for defining the term, and some difference of opinion is possible as to the degree to which a given operating system or application is Unix-like. The Open Group owns the UNIX trademark and administers the Single UNIX Specification and they do not approve of the construction Unix-like, and consider it a misuse of their trademark. Other parties frequently treat Unix as a genericized trademark, in 2007, Wayne R. Gray sued to dispute the status of UNIX as a trademark, but lost his case, and lost again on appeal, with the court upholding the trademark and its ownership. Unix-like systems started to appear in the late 1970s and early 1980s, many proprietary versions, such as Idris, UNOS, Coherent, and UniFlex, aimed to provide businesses with the functionality available to academic users of UNIX. These largely displaced the proprietary clones, growing incompatibility among these systems led to the creation of interoperability standards, including POSIX and the Single UNIX Specification. Various free, low-cost, and unrestricted substitutes for UNIX emerged in the 1980s and 1990s, including 4. 4BSD, Linux, some of these have in turn been the basis for commercial Unix-like systems, such as BSD/OS and OS X. The various BSD variants are notable in that they are in fact descendants of UNIX, however, the BSD code base has evolved since then, replacing all of the AT&T code. Since the BSD variants are not certified as compliant with the Single UNIX Specification, dennis Ritchie, one of the original creators of Unix, expressed his opinion that Unix-like systems such as Linux are de facto Unix systems. Eric S. Raymond and Rob Landley have suggested there are three kinds of Unix-like systems, Genetic UNIX Those systems with a historical connection to the AT&T codebase. Most commercial UNIX systems fall into this category, so do the BSD systems, which are descendants of work done at the University of California, Berkeley in the late 1970s and early 1980s. Some of these systems have no original AT&T code but can trace their ancestry to AT&T designs. Trademark or branded UNIX These systems—largely commercial in nature—have been determined by the Open Group to meet the Single UNIX Specification and are allowed to carry the UNIX name, many ancient UNIX systems no longer meet this definition. Around 2001, Linux was given the opportunity to get a certification including free help from the POSIX chair Andrew Josey for the price of one dollar. Some non-Unix-like operating systems provide a Unix-like compatibility layer, with degrees of Unix-like functionality. IBM z/OSs UNIX System Services is sufficiently complete to be certified as trademark UNIX, cygwin and MSYS both provide a GNU environment on top of the Microsoft Windows user API, sufficient for most common open source software to be compiled and run. Subsystem for Unix-based Applications provides Unix-like functionality as a Windows NT subsystem, Windows Subsystem for Linux provides a Linux-compatible kernel interface developed by Microsoft and containing no Linux code, with Ubuntu user-mode binaries running on top of it
40.
Linux
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Linux is a Unix-like computer operating system assembled under the model of free and open-source software development and distribution. The defining component of Linux is the Linux kernel, an operating system kernel first released on September 17,1991 by Linus Torvalds, the Free Software Foundation uses the name GNU/Linux to describe the operating system, which has led to some controversy. Linux was originally developed for computers based on the Intel x86 architecture. Because of the dominance of Android on smartphones, Linux has the largest installed base of all operating systems. Linux is also the operating system on servers and other big iron systems such as mainframe computers. It is used by around 2. 3% of desktop computers, the Chromebook, which runs on Chrome OS, dominates the US K–12 education market and represents nearly 20% of the sub-$300 notebook sales in the US. Linux also runs on embedded systems – devices whose operating system is built into the firmware and is highly tailored to the system. This includes TiVo and similar DVR devices, network routers, facility automation controls, televisions, many smartphones and tablet computers run Android and other Linux derivatives. The development of Linux is one of the most prominent examples of free, the underlying source code may be used, modified and distributed—commercially or non-commercially—by anyone under the terms of its respective licenses, such as the GNU General Public License. Typically, Linux is packaged in a known as a Linux distribution for both desktop and server use. Distributions intended to run on servers may omit all graphical environments from the standard install, because Linux is freely redistributable, anyone may create a distribution for any intended use. The Unix operating system was conceived and implemented in 1969 at AT&Ts Bell Laboratories in the United States by Ken Thompson, Dennis Ritchie, Douglas McIlroy, first released in 1971, Unix was written entirely in assembly language, as was common practice at the time. Later, in a key pioneering approach in 1973, it was rewritten in the C programming language by Dennis Ritchie, the availability of a high-level language implementation of Unix made its porting to different computer platforms easier. Due to an earlier antitrust case forbidding it from entering the computer business, as a result, Unix grew quickly and became widely adopted by academic institutions and businesses. In 1984, AT&T divested itself of Bell Labs, freed of the legal obligation requiring free licensing, the GNU Project, started in 1983 by Richard Stallman, has the goal of creating a complete Unix-compatible software system composed entirely of free software. Later, in 1985, Stallman started the Free Software Foundation, by the early 1990s, many of the programs required in an operating system were completed, although low-level elements such as device drivers, daemons, and the kernel were stalled and incomplete. Linus Torvalds has stated that if the GNU kernel had been available at the time, although not released until 1992 due to legal complications, development of 386BSD, from which NetBSD, OpenBSD and FreeBSD descended, predated that of Linux. Torvalds has also stated that if 386BSD had been available at the time, although the complete source code of MINIX was freely available, the licensing terms prevented it from being free software until the licensing changed in April 2000
41.
Berkeley Software Distribution
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Berkeley Software Distribution is a Unix operating system derivative developed and distributed by the Computer Systems Research Group of the University of California, Berkeley, from 1977 to 1995. Today the term BSD is often used non-specifically to refer to any of the BSD descendants which together form a branch of the family of Unix-like operating systems, operating systems derived from the original BSD code remain actively developed and widely used. Historically, BSD has been considered a branch of Unix, Berkeley Unix, because it shared the initial codebase, in the 1980s, BSD was widely adopted by vendors of workstation-class systems in the form of proprietary Unix variants such as DEC ULTRIX and Sun Microsystems SunOS. This can be attributed to the ease with which it could be licensed, FreeBSD, OpenBSD, NetBSD, Darwin, and PC-BSD. The earliest distributions of Unix from Bell Labs in the 1970s included the source code to the system, allowing researchers at universities to modify. A larger PDP-11/70 was installed at Berkeley the following year, using money from the Ingres database project, also in 1975, Ken Thompson took a sabbatical from Bell Labs and came to Berkeley as a visiting professor. He helped to install Version 6 Unix and started working on a Pascal implementation for the system, graduate students Chuck Haley and Bill Joy improved Thompsons Pascal and implemented an improved text editor, ex. Other universities became interested in the software at Berkeley, and so in 1977 Joy started compiling the first Berkeley Software Distribution, 1BSD was an add-on to Version 6 Unix rather than a complete operating system in its own right. Some thirty copies were sent out, some 75 copies of 2BSD were sent out by Bill Joy. 2. 9BSD from 1983 included code from 4. 1cBSD, the most recent release,2. 11BSD, was first issued in 1992. As of 2008, maintenance updates from volunteers are still continuing, a VAX computer was installed at Berkeley in 1978, but the port of Unix to the VAX architecture, UNIX/32V, did not take advantage of the VAXs virtual memory capabilities. 3BSD was also alternatively called Virtual VAX/UNIX or VMUNIX, and BSD kernel images were normally called /vmunix until 4. 4BSD, 4BSD offered a number of enhancements over 3BSD, notably job control in the previously released csh, delivermail, reliable signals, and the Curses programming library. In a 1985 review of BSD releases, John Quarterman et al, many installations inside the Bell System ran 4. 1BSD. 4. 1BSD was a response to criticisms of BSDs performance relative to the dominant VAX operating system, the 4. 1BSD kernel was systematically tuned up by Bill Joy until it could perform as well as VMS on several benchmarks. Back at Bell Labs,4. 1cBSD became the basis of the 8th Edition of Research Unix, to guide the design of 4. The committee met from April 1981 to June 1983, apart from the Fast File System, several features from outside contributors were accepted, including disk quotas and job control. Sun Microsystems provided testing on its Motorola 68000 machines prior to release, the official 4. 2BSD release came in August 1983. On a lighter note, it marked the debut of BSDs daemon mascot in a drawing by John Lasseter that appeared on the cover of the printed manuals distributed by USENIX
