1.
Software developer
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A software developer is a person concerned with facets of the software development process, including the research, design, programming, and testing of computer software. Other job titles which are used with similar meanings are programmer, software analyst. According to developer Eric Sink, the differences between system design, software development, and programming are more apparent, even more so that developers become systems architects, those who design the multi-leveled architecture or component interactions of a large software system. In a large company, there may be employees whose sole responsibility consists of one of the phases above. In smaller development environments, a few people or even an individual might handle the complete process. The word software was coined as a prank as early as 1953, before this time, computers were programmed either by customers, or the few commercial computer vendors of the time, such as UNIVAC and IBM. The first company founded to provide products and services was Computer Usage Company in 1955. The software industry expanded in the early 1960s, almost immediately after computers were first sold in mass-produced quantities, universities, government, and business customers created a demand for software. Many of these programs were written in-house by full-time staff programmers, some were distributed freely between users of a particular machine for no charge. Others were done on a basis, and other firms such as Computer Sciences Corporation started to grow. The computer/hardware makers started bundling operating systems, systems software and programming environments with their machines, new software was built for microcomputers, so other manufacturers including IBM, followed DECs example quickly, resulting in the IBM AS/400 amongst others. The industry expanded greatly with the rise of the computer in the mid-1970s. In the following years, it created a growing market for games, applications. DOS, Microsofts first operating system product, was the dominant operating system at the time, by 2014 the role of cloud developer had been defined, in this context, one definition of a developer in general was published, Developers make software for the world to use. The job of a developer is to crank out code -- fresh code for new products, code fixes for maintenance, code for business logic, bus factor Software Developer description from the US Department of Labor
2.
GNU Project
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The GNU Project /ɡnuː/ is a free-software, mass-collaboration project, first announced on September 27,1983 by Richard Stallman at MIT. GNU software guarantees these freedom-rights legally, and is free software. In order to ensure that the software of a computer grants its users all freedom rights, even the most fundamental and important part. Stallman decided to call this operating system GNU, basing its design on that of Unix, development was initiated in January 1984. In 1991, the kernel Linux appeared, developed outside of the GNU project by Linus Torvalds, combined with the operating system utilities already developed by the GNU project, it allowed for the first operating system that was free software, known as Linux or GNU/Linux. The projects current work includes development, awareness building, political campaigning and sharing of the new material. Richard Stallman announced his intent to start coding the GNU Project in a Usenet message in September 1983, when the GNU project first started they had an Emacs text editor with Lisp for writing editor commands, a source level debugger, a yacc-compatible parser generator, and a linker. The GNU system required its own C compiler and tools to be free software, by June 1987, the project had accumulated and developed free software for an assembler, an almost finished portable optimizing C compiler, an editor, and various Unix utilities. They had a kernel that needed more updates. Once the kernel and the compiler were finished, GNU was able to be used for program development, the main goal was to create many other applications to be like the Unix system. GNU was able to run Unix programs but was not identical to it, GNU incorporated longer file names, file version numbers, and a crashproof file system. The GNU Manifesto was written to support and participation from others for the project. Programmers were encouraged to take part in any aspect of the project that interested them, people could donate funds, computer parts, or even their own time to write code and programs for the project. The origins and development of most aspects of the GNU Project are shared in a narrative in the Emacs help system. It is the detailed history as at their web site. The GNU Manifesto was written by Richard Stallman to gain support, to implement these freedoms, users needed full access to code. Although most of the GNU Projects output is technical in nature, it was launched as a social, ethical, as well as producing software and licenses, the GNU Project has published a number of writings, the majority of which were authored by Richard Stallman. The GNU project uses software that is free for users to copy, edit and it is free in the sense that users can change the software to fit individual needs
3.
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
4.
Assembly language
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Each assembly language is specific to a particular computer architecture. In contrast, most high-level programming languages are generally portable across multiple architectures, Assembly language may also be called symbolic machine code. Assembly language is converted into machine code by a utility program referred to as an assembler. The conversion process is referred to as assembly, or assembling the source code, Assembly time is the computational step where an assembler is run. Assembly language uses a mnemonic to represent each low-level machine instruction or opcode, typically also each architectural register, flag, depending on the architecture, these elements may also be combined for specific instructions or addressing modes using offsets or other data as well as fixed addresses. Many assemblers offer additional mechanisms to facilitate development, to control the assembly process. A macro assembler includes a facility so that assembly language text can be represented by a name. A cross assembler is an assembler that is run on a computer or operating system of a different type from the system on which the code is to run. Cross-assembling facilitates the development of programs for systems that do not have the resources to support software development, a microassembler is a program that helps prepare a microprogram, called firmware, to control the low level operation of a computer. A meta-assembler is a used in some circles for a program that accepts the syntactic and semantic description of an assembly language. An assembler program creates object code by translating combinations of mnemonics and syntax for operations and this representation typically includes an operation code as well as other control bits and data. The assembler also calculates constant expressions and resolves symbolic names for memory locations, the use of symbolic references is a key feature of assemblers, saving tedious calculations and manual address updates after program modifications. Most assemblers also include facilities for performing textual substitution – e. g. to generate common short sequences of instructions as inline. Some assemblers may also be able to some simple types of instruction set-specific optimizations. One concrete example of this may be the ubiquitous x86 assemblers from various vendors, most of them are able to perform jump-instruction replacements in any number of passes, on request. Like early programming languages such as Fortran, Algol, Cobol and Lisp, assemblers have been available since the 1950s, however, assemblers came first as they are far simpler to write than compilers for high-level languages. There may be several assemblers with different syntax for a particular CPU or instruction set architecture, despite different appearances, different syntactic forms generally generate the same numeric machine code, see further below. A single assembler may also have different modes in order to support variations in syntactic forms as well as their exact semantic interpretations, there are two types of assemblers based on how many passes through the source are needed to produce the executable program
5.
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
6.
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
7.
Free software
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The right to study and modify software entails availability of the software source code to its users. This right is conditional on the person actually having a copy of the software. Richard Stallman used the existing term free software when he launched the GNU Project—a collaborative effort to create a freedom-respecting operating system—and the Free Software Foundation. The FSFs Free Software Definition states that users of software are free because they do not need to ask for permission to use the software. Free software thus differs from proprietary software, such as Microsoft Office, Google Docs, Sheets, and Slides or iWork from Apple, which users cannot study, change, freeware, which is a category of freedom-restricting proprietary software that does not require payment for use. For computer programs that are covered by law, software freedom is achieved with a software license. Software that is not covered by law, such as software in the public domain, is free if the source code is in the public domain. Proprietary software, including freeware, use restrictive software licences or EULAs, Users are thus prevented from changing the software, and this results in the user relying on the publisher to provide updates, help, and support. This situation is called vendor lock-in, Users often may not reverse engineer, modify, or redistribute proprietary software. Other legal and technical aspects, such as patents and digital rights management may restrict users in exercising their rights. Free software may be developed collaboratively by volunteer computer programmers or by corporations, as part of a commercial, from the 1950s up until the early 1970s, it was normal for computer users to have the software freedoms associated with free software, which was typically public domain software. Software was commonly shared by individuals who used computers and by manufacturers who welcomed the fact that people were making software that made their hardware useful. Organizations of users and suppliers, for example, SHARE, were formed to exchange of software. As software was written in an interpreted language such as BASIC. Software was also shared and distributed as printed source code in computer magazines and books, in United States vs. IBM, filed January 17,1969, the government charged that bundled software was anti-competitive. While some software might always be free, there would henceforth be an amount of software produced primarily for sale. In the 1970s and early 1980s, the industry began using technical measures to prevent computer users from being able to study or adapt the software as they saw fit. In 1980, copyright law was extended to computer programs, Software development for the GNU operating system began in January 1984, and the Free Software Foundation was founded in October 1985
8.
Software release life cycle
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Usage of the alpha/beta test terminology originated at IBM. As long ago as the 1950s, IBM used similar terminology for their hardware development, a test was the verification of a new product before public announcement. B test was the verification before releasing the product to be manufactured, C test was the final test before general availability of the product. Martin Belsky, a manager on some of IBMs earlier software projects claimed to have invented the terminology, IBM dropped the alpha/beta terminology during the 1960s, but by then it had received fairly wide notice. The usage of beta test to refer to testing done by customers was not done in IBM, rather, IBM used the term field test. Pre-alpha refers to all activities performed during the project before formal testing. These activities can include requirements analysis, software design, software development, in typical open source development, there are several types of pre-alpha versions. Milestone versions include specific sets of functions and are released as soon as the functionality is complete, the alpha phase of the release life cycle is the first phase to begin software testing. In this phase, developers generally test the software using white-box techniques, additional validation is then performed using black-box or gray-box techniques, by another testing team. Moving to black-box testing inside the organization is known as alpha release, alpha software can be unstable and could cause crashes or data loss. Alpha software may not contain all of the features that are planned for the final version, in general, external availability of alpha software is uncommon in proprietary software, while open source software often has publicly available alpha versions. The alpha phase usually ends with a freeze, indicating that no more features will be added to the software. At this time, the software is said to be feature complete, Beta, named after the second letter of the Greek alphabet, is the software development phase following alpha. Software in the stage is also known as betaware. Beta phase generally begins when the software is complete but likely to contain a number of known or unknown bugs. Software in the phase will generally have many more bugs in it than completed software, as well as speed/performance issues. The focus of beta testing is reducing impacts to users, often incorporating usability testing, the process of delivering a beta version to the users is called beta release and this is typically the first time that the software is available outside of the organization that developed it. Beta version software is useful for demonstrations and previews within an organization
9.
P6 (microarchitecture)
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The P6 microarchitecture is the sixth-generation Intel x86 microarchitecture, implemented by the Pentium Pro microprocessor that was introduced in November 1995. It is sometimes referred to as i686 and it was succeeded by the NetBurst microarchitecture in 2000, but eventually revived in the Pentium M line of microprocessors. The successor to the Pentium M variant of the P6 microarchitecture is the Core microarchitecture which in turn is derived from the P6 microarchitecture. The P6 core was the sixth generation Intel microprocessor in the x86 line, the first implementation of the P6 core was the Pentium Pro CPU in 1995, the immediate successor to the original Pentium design. Some techniques first used in the x86 space in the P6 core include, Speculative execution and out-of-order completion and this lessened pipeline stalls, and in part enabled greater speed-scaling of the Pentium Pro and successive generations of CPUs. PAE and a wider 36-bit address bus to support 64 GB of physical memory, register renaming, which enabled more efficient execution of multiple instructions in the pipeline. CMOV instructions heavily used in compiler optimization, other new instructions, FCMOV, FCOMI/FCOMIP/FUCOMI/FUCOMIP, RDPMC, UD2. New instructions in Pentium II Deschutes core, FXSAVE, FXRSTOR, new instructions in Pentium III, SSE. The P6 line of processing cores was succeeded with the NetBurst architecture which appeared with the introduction of Pentium 4 and this was a completely different design based on the use of very long pipelines that favoured high clock speed at the cost of lower IPC, and higher power consumption. The Netburst-based processors were not as efficient per clock or per watt compared to their P6 predecessors. Mobile Pentium 4 processors ran much hotter than Pentium III-M processors and its inefficiency affected not only the cooling system complexity, but also the all-important battery life. Realizing their new microarchitecture wasnt the best choice for the mobile space, the result was a modernized P6 design called the Pentium M, Design Overview Quad-pumped Front Side Bus. With the initial Banias core, Intel adopted the 400 MT/s FSB first used in Pentium 4, the Dothan core moved to the 533 MT/s FSB, following Pentium 4s evolution. Initially 1 MB in the Banias core, then 2 MB in the Dothan core, Dynamic cache activation by quadrant selector from sleep states. SSE2 Streaming SIMD Extensions 2 support, a 12- or 14-stage instruction pipeline that allows for higher clock speeds. Addition of global history, indirect prediction, and loop prediction to branch prediction table, micro-ops Fusion of certain sub-instructions mediated by decoding units. X86 commands can result in fewer RISC micro-operations and thus require fewer processor cycles to complete, the Pentium M was the most power efficient x86 processor for notebooks for several years, consuming a maximum of 27 watts at maximum load and 4-5 watts while idle. The processing efficiency gains brought about by its modernization allowed it to rival the Mobile Pentium 4 clocked over 1 GHz higher and equipped with more memory
10.
Kernel (operating system)
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The kernel is a computer program that is the core of a computers operating system, with complete control over everything in the system. It is the first program loaded on start-up and it handles the rest of start-up as well as input/output requests from software, translating them into data-processing instructions for the central processing unit. It handles memory and peripherals like keyboards, monitors, printers, the critical code of the kernel is usually loaded into a protected area of memory, which prevents it from being overwritten by applications or other, more minor parts of the operating system. The kernel performs its tasks, such as running processes and handling interrupts, in contrast, everything a user does is in user space, writing text in a text editor, running programs in a GUI, etc. This separation prevents user data and kernel data from interfering with other and causing instability. The kernels interface is an abstraction layer. When a process makes requests of the kernel, it is called a system call, Kernel designs differ in how they manage these system calls and resources. A monolithic kernel runs all the operating instructions in the same address space. A microkernel runs most processes in space, for modularity. The kernel takes responsibility for deciding at any time which of the running programs should be allocated to the processor or processors. Random-access memory Random-access memory is used to both program instructions and data. Typically, both need to be present in memory in order for a program to execute, often multiple programs will want access to memory, frequently demanding more memory than the computer has available. The kernel is responsible for deciding which memory each process can use, input/output devices I/O devices include such peripherals as keyboards, mice, disk drives, printers, network adapters, and display devices. The kernel allocates requests from applications to perform I/O to an appropriate device, key aspects necessary in resource management are the definition of an execution domain and the protection mechanism used to mediate the accesses to the resources within a domain. Kernels also usually provide methods for synchronization and communication between processes called inter-process communication, finally, a kernel must provide running programs with a method to make requests to access these facilities. The kernel has full access to the memory and must allow processes to safely access this memory as they require it. Often the first step in doing this is virtual addressing, usually achieved by paging and/or segmentation, virtual addressing allows the kernel to make a given physical address appear to be another address, the virtual address. This allows every program to behave as if it is the one running
11.
Software license
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A software license is a legal instrument governing the use or redistribution of software. Under United States copyright law all software is copyright protected, in code as also object code form. The only exception is software in the public domain, most distributed software can be categorized according to its license type. Two common categories for software under copyright law, and therefore with licenses which grant the licensee specific rights, are proprietary software and free, unlicensed software outside the copyright protection is either public domain software or software which is non-distributed, non-licensed and handled as internal business trade secret. Contrary to popular belief, distributed unlicensed software is copyright protected. Examples for this are unauthorized software leaks or software projects which are placed on public software repositories like GitHub without specified license. As voluntarily handing software into the domain is problematic in some international law domains, there are also licenses granting PD-like rights. Therefore, the owner of a copy of software is legally entitled to use that copy of software. Hence, if the end-user of software is the owner of the respective copy, as many proprietary licenses only enumerate the rights that the user already has under 17 U. S. C. §117, and yet proclaim to take away from the user. Proprietary software licenses often proclaim to give software publishers more control over the way their software is used by keeping ownership of each copy of software with the software publisher. The form of the relationship if it is a lease or a purchase, for example UMG v. Augusto or Vernor v. Autodesk. The ownership of goods, like software applications and video games, is challenged by licensed. The Swiss based company UsedSoft innovated the resale of business software and this feature of proprietary software licenses means that certain rights regarding the software are reserved by the software publisher. Therefore, it is typical of EULAs to include terms which define the uses of the software, the most significant effect of this form of licensing is that, if ownership of the software remains with the software publisher, then the end-user must accept the software license. In other words, without acceptance of the license, the end-user may not use the software at all, one example of such a proprietary software license is the license for Microsoft Windows. The most common licensing models are per single user or per user in the appropriate volume discount level, Licensing per concurrent/floating user also occurs, where all users in a network have access to the program, but only a specific number at the same time. Another license model is licensing per dongle which allows the owner of the dongle to use the program on any computer, Licensing per server, CPU or points, regardless the number of users, is common practice as well as site or company licenses
12.
GNU General Public License
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The GNU General Public License is a widely used free software license, which guarantees end users the freedom to run, study, share and modify the software. The license was written by Richard Stallman of the Free Software Foundation for the GNU Project. The GPL is a license, which means that derivative work can only be distributed under the same license terms. This is in distinction to permissive free licenses, of which the BSD licenses. GPL was the first copyleft license for general use, historically, the GPL license family has been one of the most popular software licenses in the free and open-source software domain. Prominent free software licensed under the GPL include the Linux kernel. In 2007, the version of the license was released to address some perceived problems with the second version that were discovered during its long-time usage. To keep the license up to date, the GPL license includes an optional any later version clause, developers can omit it when licensing their software, for instance the Linux kernel is licensed under GPLv2 without the any later version clause. The GPL was written by Richard Stallman in 1989, for use with programs released as part of the GNU project, the original GPL was based on a unification of similar licenses used for early versions of GNU Emacs, the GNU Debugger and the GNU C Compiler. These licenses contained similar provisions to the modern GPL, but were specific to each program, rendering them incompatible, Stallmans goal was to produce one license that could be used for any project, thus making it possible for many projects to share code. The second version of the license, version 2, was released in 1991, version 3 was developed to attempt to address these concerns and was officially released on 29 June 2007. Version 1 of the GNU GPL, released on 25 February 1989, the first problem was that distributors may publish binary files only—executable, but not readable or modifiable by humans. To prevent this, GPLv1 stated that any vendor distributing binaries must also make the source code available under the same licensing terms. The second problem was that distributors might add restrictions, either to the license, the union of two sets of restrictions would apply to the combined work, thus adding unacceptable restrictions. To prevent this, GPLv1 stated that modified versions, as a whole, had to be distributed under the terms in GPLv1. Therefore, software distributed under the terms of GPLv1 could be combined with software under more permissive terms, according to Richard Stallman, the major change in GPLv2 was the Liberty or Death clause, as he calls it – Section 7. The section says that licensees may distribute a GPL-covered work only if they can all of the licenses obligations. In other words, the obligations of the license may not be severed due to conflicting obligations and this provision is intended to discourage any party from using a patent infringement claim or other litigation to impair users freedom under the license
13.
Microkernel
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In computer science, a microkernel is the near-minimum amount of software that can provide the mechanisms needed to implement an operating system. These mechanisms include low-level address space management, thread management, If the hardware provides multiple rings or CPU modes, the microkernel may be the only software executing at the most privileged level, which is generally referred to as supervisor or kernel mode. Traditional operating system functions, such as drivers, protocol stacks. In terms of the code size, as a general rule microkernels tend to be smaller than monolithic kernels. The MINIX3 microkernel, for example, has approximately 12,000 lines of code, in 1967, Regnecentralen was installing a RC4000 prototype in a Polish fertilizer plant in Puławy. The computer used a small operating system tailored for the needs of the plant. Brinch Hansen and his team became concerned with the lack of generality and reusability of the RC4000 system and they feared that each installation would require a different operating system so they started to investigate novel and more general ways of creating software for the RC4000. In 1969, their effort resulted in the completion of the RC4000 Multiprogramming System and its nucleus provided inter-process communication based on message-passing for up to 23 unprivileged processes, out of which 8 at a time were protected from one another. Besides these elementary mechanisms, it had no strategy for program execution. This strategy was to be implemented by a hierarchy of running programs in which parent processes had complete control over child processes, microkernels were first developed in the 1980s as a response to changes in the computer world, and to several challenges adapting existing mono-kernels to these new systems. New device drivers, protocol stacks, file systems and other systems were being developed all the time. This code was located in the monolithic kernel, and thus required considerable work. This would not only allow these services to be easily worked on. Moreover, it would allow entirely new operating systems to be built up on a common core, microkernels were a very hot topic in the 1980s when the first usable local area networks were being introduced. The same mechanisms that allowed the kernel to be distributed into user space also allowed the system to be distributed across network links. The first microkernels, notably Mach, proved to have disappointing performance, however, during this time the speed of computers grew greatly in relation to networking systems, and the disadvantages in performance came to overwhelm the advantages in development terms. As of 2012, the Mach-based GNU Hurd is also functional and included in testing versions of Arch Linux, although major work on microkernels had largely ended, experimenters continued development. Microkernels are closely related to exokernels, early operating system kernels were rather small, partly because computer memory was limited
14.
GNU
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GNU /ɡnuː/ is an operating system and an extensive collection of computer software. GNU is composed wholly of free software, most of which is licensed under the GNU Projects own GPL, GNU is a recursive acronym for GNUs Not Unix. Chosen because GNUs design is Unix-like, but differs from Unix by being free software, the GNU project includes an operating system kernel, GNU HURD, which was the original focus of the Free Software Foundation. However, non-GNU kernels, most famously Linux, can also be used with GNU software, and since the kernel is the least mature part of GNU, the combination of GNU software and the Linux kernel is commonly known as Linux. Richard Stallman, the founder of the project, views GNU as a means to a social end. unix-wizards. Software development began on January 5,1984, when Stallman quit his job at the Lab so that they could not claim ownership or interfere with distributing GNU components as free software, Richard Stallman chose the name by using various plays on words, including the song The Gnu. The goal was to bring a free software operating system into existence. This philosophy was published as the GNU Manifesto in March 1985. It was thus decided that the development would be started using C and Lisp as system programming languages, at the time, Unix was already a popular proprietary operating system. The design of Unix was modular, so it could be reimplemented piece by piece, in October 1985, Stallman set up the Free Software Foundation. In the late 1980s and 1990s, the FSF hired software developers to write the software needed for GNU, as GNU gained prominence, interested businesses began contributing to development or selling GNU software and technical support. The most prominent and successful of these was Cygnus Solutions, now part of Red Hat, GNU developers have contributed to Linux ports of GNU applications and utilities, which are now also widely used on other operating systems such as BSD variants, Solaris and macOS. Many GNU programs have been ported to other operating systems, including proprietary platforms such as Microsoft Windows, GNU programs have been shown to be more reliable than their proprietary Unix counterparts. As of November 2015, there are a total of 466 GNU packages hosted on the official GNU development site. With the April 30,2015 release of the Debian GNU/HURD2015 distro, GNU OS now provides the components to assemble a system that users can install. This includes the GNU Hurd kernel, that is currently in a pre-production state, the Hurd status page states that it may not be ready for production use, as there are still some bugs and missing features. However, it should be a base for further development. Due to Hurd not being ready for use, in practice these operating systems are Linux distributions
15.
Free Software Foundation
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The FSF was incorporated in Massachusetts, USA, where it is also based. From its founding until the mid-1990s, FSFs funds were used to employ software developers to write free software for the GNU Project. Since the mid-1990s, the FSFs employees and volunteers have worked on legal and structural issues for the free software movement. Consistent with its goals, the FSF aims to use free software on its own computers. The Free Software Foundation was founded in 1985 as a non-profit corporation supporting free software development and it continued existing GNU projects such as the sale of manuals and tapes, and employed developers of the free software system. Since then, it has continued these activities, as well as advocating for the free software movement, the FSF is also the steward of several free software licenses, meaning it publishes them and has the ability to make revisions as needed. The FSF holds the copyrights on many pieces of the GNU system, as holder of these copyrights, it has the authority to enforce the copyleft requirements of the GNU General Public License when copyright infringement occurs on that software. From 1991 until 2001, GPL enforcement was done informally, usually by Stallman himself, often with assistance from FSFs lawyer, typically, GPL violations during this time were cleared up by short email exchanges between Stallman and the violator. In the interest of promoting copyleft assertiveness by software companies to the level that the FSF was already doing, in 2004 Harald Welte launched gpl-violations. org. In late 2001, Bradley M. Kuhn, with the assistance of Moglen, David Turner, from 2002-2004, high-profile GPL enforcement cases, such as those against Linksys and OpenTV, became frequent. GPL enforcement and educational campaigns on GPL compliance was a focus of the FSFs efforts during this period. In March 2003, SCO filed suit against IBM alleging that IBMs contributions to free software, including FSFs GNU. While FSF was never a party to the lawsuit, FSF was subpoenaed on November 5,2003, during 2003 and 2004, FSF put substantial advocacy effort into responding to the lawsuit and quelling its negative impact on the adoption and promotion of free software. From 2003 to 2005, FSF held legal seminars to explain the GPL, usually taught by Bradley M. Kuhn and Daniel Ravicher, these seminars offered CLE credit and were the first effort to give formal legal education on the GPL. In 2007, the FSF published the version of the GNU General Public License after significant outside input. In December 2008, FSF filed a lawsuit against Cisco for using GPL-licensed components shipped with Linksys products, Cisco was notified of the licensing issue in 2003 but Cisco repeatedly disregarded its obligations under the GPL. The GNU project The original purpose of the FSF was to promote the ideals of free software, the organization developed the GNU operating system as an example of this. GNU licenses The GNU General Public License is a widely used license for software projects
16.
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
17.
Linux kernel
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The Linux kernel is a monolithic Unix-like computer operating system kernel. The Android operating system for computers, smartphones and smartwatches is also based atop the Linux kernel. While the adoption on desktop computers is low, Linux-based operating systems dominate nearly every segment of computing. As of November 2016, all but two of the worlds 500 most powerful supercomputers run Linux, Linux rapidly attracted developers and users who adopted it as the kernel for other free software projects, notably the GNU Operating System. The Linux kernel has received contributions from nearly 12,000 programmers from more than 1,200 companies, the Linux kernel API, the application programming interface through which user programs interact with the kernel, is meant to be very stable and to not break userspace programs. As part of the functionality, device drivers control the hardware. However, the interface between the kernel and loadable kernel modules, unlike in many other kernels and operating systems, is not meant to be stable by design. The Linux kernel, developed by contributors worldwide, is a prominent example of free, day-to-day development discussions take place on the Linux kernel mailing list. The Linux kernel is released under the GNU General Public License version 2, in April 1991, Linus Torvalds, at the time a 21-year-old computer science student at the University of Helsinki, Finland, started working on some simple ideas for an operating system. He started with a task switcher in Intel 80386 assembly language, on 25 August 1991, Torvalds posted the following to comp. os. minix, a newsgroup on Usenet, Im doing a operating system for 386 AT clones. This has been brewing since April, and is starting to get ready, id like any feedback on things people like/dislike in minix, as my OS resembles it somewhat. Ive currently ported bash and gcc, and things seem to work and this implies that Ill get something practical within a few months Yes - its free of any minix code, and it has a multi-threaded fs. It is NOT portable, and it never will support anything other than AT-harddisks, as thats all I have. Its mostly in C, but most people wouldnt call what I write C and it uses every conceivable feature of the 386 I could find, as it was also a project to teach me about the 386. As already mentioned, it uses a MMU, for both paging and segmentation and its the segmentation that makes it REALLY386 dependent. Some of my C-files are almost as much assembler as C, unlike minix, I also happen to LIKE interrupts, so interrupts are handled without trying to hide the reason behind them. After that, many people contributed code to the project, early on, the MINIX community contributed code and ideas to the Linux kernel. At the time, the GNU Project had created many of the components required for an operating system
18.
Server (computing)
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In computing, a server is a computer program or a device that provides functionality for other programs or devices, called clients. This architecture is called the model, and a single overall computation is distributed across multiple processes or devices. Servers can provide various functionalities, often called services, such as sharing data or resources among multiple clients, a single server can serve multiple clients, and a single client can use multiple servers. A client process may run on the device or may connect over a network to a server on a different device. Typical servers are database servers, file servers, mail servers, print servers, web servers, game servers, designating a computer as server-class hardware implies that it is specialized for running servers on it. The use of the server in computing comes from queueing theory, where it dates to the mid 20th century, being notably used in Kendall. In earlier papers, such as the Erlang, more terms such as operators are used. In computing, server dates at least to RFC5, one of the earliest documents describing ARPANET, the use of serving also dates to early documents, such as RFC4, contrasting serving-host with using-host. The Jargon File defines server in the sense of a process performing service for requests, usually remote, with the 1981 version reading. A kind of DAEMON which performs a service for the requester, strictly speaking, the term server refers to a computer program or process. Through metonymy, it refers to a used to running one or several server programs. On a network, such a device is called a host, in addition to server, the words serve and service are frequently used, though servicer and servant are not. The word service may refer to either the form of functionality. Alternatively, it may refer to a program that turns a computer into a server. Originally used as servers serve users, in the sense of obey, today one says that servers serve data. For instance, web servers serve web pages to users or service their requests, the server is part of the client–server model, in this model, a server serves data for clients. The nature of communication between a client and server is request and response and this is in contrast with peer-to-peer model in which the relationship is on-demand reciprocation. In principle, any computerized process that can be used or called by another process is a server, thus any general purpose computer connected to a network can host servers
19.
Daemon (computing)
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In multitasking computer operating systems, a daemon is a computer program that runs as a background process, rather than being under the direct control of an interactive user. Traditionally, the names of a daemon end with the letter d, for clarification that the process is, in fact, a daemon. For example, syslogd is the daemon that implements the system logging facility, in a Unix environment, the parent process of a daemon is often, but not always, the init process. In addition, a daemon launched by forking and exiting typically must perform other operations, such procedures are often implemented in various convenience routines such as daemon in Unix. Systems often start daemons at boot time which will respond to requests, hardware activity. Daemons such as cron may also perform defined tasks at scheduled times, the term was coined by the programmers of MITs Project MAC. They took the name from Maxwells demon, an imaginary being from an experiment that constantly works in the background. Maxwells Demon is consistent with Greek mythologys interpretation of a daemon as a supernatural being working in the background, however, BSD and some of its derivatives have adopted a Christian demon as their mascot rather than a Greek daemon. The word daemon is a spelling of demon, and is pronounced /ˈdiːmən/ DEE-mən. In the context of software, the original pronunciation /ˈdiːmən/ has drifted to /ˈdeɪmən/ DAY-mən for some speakers. Alternate terms for daemon are service, started task, and ghost job, after the term was adopted for computer use, it was rationalized as a backronym for Disk And Execution MONitor. Daemons which connect to a network are examples of network services. However, more commonly, a daemon may be any background process, executing as a background task by forking and exiting. This is required sometimes for the process to become a session leader and it also allows the parent process to continue its normal execution. Setting the root directory as the current working directory so that the process does not keep any directory in use that may be on a file system. Required files will be opened later, in the Microsoft DOS environment, daemon-like programs were implemented as terminate and stay resident software. On Microsoft Windows NT systems, programs called Windows services perform the functions of daemons and they run as processes, usually do not interact with the monitor, keyboard, and mouse, and may be launched by the operating system at boot time. However, any Windows application can perform the role of a daemon, not just a service, on the classic Mac OS, optional features and services were provided by files loaded at startup time that patched the operating system, these were known as system extensions and control panels
20.
Monolithic kernel
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A monolithic kernel is an operating system architecture where the entire operating system is working in kernel space and is alone in supervisor mode. The monolithic model differs from other operating system architectures in that it defines a high-level virtual interface over computer hardware. A set of primitives or system calls implement all operating system such as process management, concurrency. Device drivers can be added to the kernel as modules and this modularity of the operating system is at the binary level and not at the architecture level. Modular monolithic operating systems are not to be confused with the level of modularity inherent in Server-Client operating systems which use microkernels. Practically speaking, dynamically loading modules is simply a more flexible way of handling the operating system image at runtime — as opposed to rebooting with a different operating system image, the modules allow easy extension of the operating systems capabilities as required. Dynamically loadable modules incur a small overhead when compared to building the module into the system image. Namely, an unloaded module need not be stored in random access memory
21.
Homophone
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A homophone is a word that is pronounced the same as another word but differs in meaning, and may differ in spelling. The words may be spelled the same, such as rose and rose, or differently, such as carat, caret, homophones that are spelled the same are also both homographs and homonyms. Homophones that are spelled differently are also called heterographs, the term homophone may also apply to units longer or shorter than words, such as phrases, letters or groups of letters that are pronounced the same as another phrase, letter or group of letters. A word or unit with this property is said to be homophonous, homophone derives from the Greek homo-, same, and phōnḗ, voice, utterance. Homophones are often used to create puns and to deceive the reader or to suggest multiple meanings, the last usage is common in poetry and creative literature. An example of this is seen in Dylan Thomass radio play Under Milk Wood, some examples from English are, pin and pen in many southern American accents. Merry, marry, and Mary in most American accents, the pairs do, due and forward, foreword are homophonous in most American accents but not in most English accents. Wordplay is particularly common in English because the multiplicity of linguistic influences offers considerable complication in spelling and meaning, malapropisms, which often create a similar comic effect, are usually near-homophones. Homophones of multiple words or phrases are known as oronyms. This term was coined by Gyles Brandreth and first published in his book The Joy of Lex, and it was used in the BBC programme Never Mind the Full Stops, examples of oronyms include, ice cream vs. Notable examples include, Initiate, My wife ate two sandwiches, initiate a bag o tater chips, Mayonnaise, Mayonnaise a lot of people here tonight. Innuendo, Hey dude I saw a bird fly innuendo, Moustache, I Moustache you a question. There are differences in such lists due to dialect pronunciations and usage of old words, in English, there are approximately 88 triples,24 quadruples,2 quintuples,1 sextet and 1 septet. If proper names are allowed then a nonet is Ayr, Aire, Eyre, heir, air, err, ere, eer, are. An extreme example is kikō, which is the pronunciation of at least 22 words, including, 機構, 紀行, 稀覯, 騎行, 貴校 (, 奇功, 貴公, 起稿, 奇行, 機巧, 寄港, 帰校, 気功, 寄稿, 機甲, 帰航, 奇効, 季候, 気孔, 起工, 気候, 帰港. The Korean language contains a combination of words that belong to Korean. For example, 화장하다, to put on makeup and 화장하다, also, 유산, inheritance and 유산, miscarriage. There are heterographs, but far fewer, contrary to the tendency in English, for example, 학문, learning, and 항문, anus
22.
Herd
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A herd is a social grouping of certain animals of the same species, either wild or domestic. The form of animal behavior associated with this is referred to as herding. The term herd is generally applied to mammals, and most particularly to the grazing ungulates that classically display this behaviour, a group of quail is often referred to as a covey. Large groups of carnivores are usually called packs, and in nature a herd is classically subject to predation from pack hunters. Special collective nouns may be used for particular taxa but for discussions of behavioural ecology. The word herd, as a noun, can refer to one who controls. Examples of herds in this sense include shepherds, goatherds, cowherds, when an association of animals is described as a herd, the implication is that the group tends to act together, but that this does not occur as a result of planning or coordination. A herd can be contrasted with a group where individuals have distinct roles. The question of why animals group together is one of the most fundamental in sociobiology and behavioural ecology. There is clearly a tradeoff involved, since on the one hand a predator may hesitate to attack a group of animals. In the case of predators, it is unclear whether the term herd is appropriate. A herd is by definition relatively unstructured, however, there may be one or a few animals which tend to be imitated by the rest of the members of the herd more than others. An animal taking this role is called an animal, since its behaviour will predict that of the herd as a whole. It cannot be assumed, however, that the animal is deliberately taking a leadership role. Control animals are not necessarily, or even usually, those that are dominant in conflict situations. Group size is an important characteristic of the environment of gregarious species. Domestic animal herds are assembled by humans for practicality in raising them and their behaviour may be quite different from that of wild herds of the same or related species, since both their composition and their history are likely to be very different. The term herd is also applied metaphorically to human beings in social psychology, however both the term and concepts that underlie its use are controversial
23.
Wildebeest
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The wildebeests, also called gnus, are a genus of antelopes, scientific name Connochaetes. They belong to the family Bovidae, which includes antelopes, cattle, goats, sheep, Connochaetes includes two species, both native to Africa, the black wildebeest, or white-tailed gnu, and the blue wildebeest, or brindled gnu. Fossil records suggest these two species diverged about one years ago, resulting in a northern and a southern species. The most obvious way of telling the two species apart are the differences in their colouring and in the way their horns are oriented. In East Africa, the blue wildebeest is the most abundant big game species, some populations perform an annual migration to new grazing grounds, but the black wildebeest is merely nomadic. Breeding in both takes place over a period of time at the end of the rainy season. Nevertheless, some fall prey to large carnivores, Wildebeest often graze in mixed herds with zebra which gives heightened awareness of potential predators. They are also alert to the signals emitted by other animals such as baboons. Wildebeest are a tourist attraction but compete with domesticated livestock for pasture and are blamed by farmers for transferring diseases and parasites to their cattle. Some illegal hunting goes on but the trend is fairly stable. The International Union for Conservation of Nature lists both as least-concern species, the wildebeest, also called the gnu is an antelope of the genus Connochaetes. Wildebeest is Dutch for wild beast or wild cattle in Afrikaans, while Connochaetes derives from the Greek words κόννος, kónnos, beard, some sources claim the name gnu originates from the Khoikhoi name for these animals, tgnu. Others contend the name and its pronunciation in English go back to the word. nu, the name Connochaetes was given by German zoologist Hinrich Lichtenstein in 1814. Wildebeest were first discovered about 1700 by Dutch settlers on their way to the interior of South Africa, due to their resemblance to wild cattle, these people called them wild ox or wildebeest. The black wildebeest was first known to westerners in the part of South Africa a century later. In the early century, one species of the wildebeest. In 1914, two races of the wildebeest were introduced, namely Gorgon a. albojubatus and G. a. mearnsi. However, in 1939, the two were again merged into a single race, Connochaetes taurinus albojubatus
24.
Inter-process communication
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In computer science, inter-process communication or interprocess communication refers specifically to the mechanisms an operating system provides to allow processes it manages to share data. Typically, applications can use IPC, categorized as clients and servers, where the client requests data, many applications are both clients and servers, as commonly seen in distributed computing. IPC is very important to the process for microkernels and nanokernels. Microkernels reduce the number of functionalities provided by the kernel and those functionalities are then obtained by communicating with servers via IPC, increasing drastically the number of IPC compared to a regular monolithic kernel. Depending on solution IPC mechanism may provide synchronization or leave it up to processes, while synchronization includes some information it is not primarily information passing communication mechanism per se. Examples of synchronization primitives are, Semaphore Spinlock Barrier Mutual exclusion Javas Remote Method Invocation ONC RPC XML-RPC or SOAP JSON-RPC Message Bus, UNIX Network Programming, Volume 2, Second Edition, Interprocess Communications. Ramachandran, M. Solomon, M. Vernon Hardware support for interprocess communication Proceedings of the 14th annual international symposium on Computer architecture, year of Publication,1987 ISBN 0-8186-0776-9 Crovella, M. Bianchini, R. LeBlanc, T. Markatos, E. Wisniewski, R. Using communication-to-computation ratio in parallel program designand performance prediction 1–4 December 1992, pp. 238–245 ISBN 0-8186-3200-3 Linux ipc man page describing System V IPC Windows IPC Beejs Guide to Unix IPC Unix Network Programming by W. Richard Stevens Interprocess Communication and Pipes in C
25.
Richard Stallman
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Richard Matthew Stallman, often known by his initials, rms, is an American software freedom activist and programmer. He campaigns for software to be distributed in a such that its users receive the freedoms to use, study, distribute. Software that ensures these freedoms is termed free software, Stallman launched the GNU Project, founded the Free Software Foundation, developed the GNU Compiler Collection and GNU Emacs, and wrote the GNU General Public License. Stallman launched the GNU Project in September 1983 to create a Unix-like computer operating system composed entirely of free software, with this, he also launched the free software movement. In October 1985 he founded the Free Software Foundation, in 1989 he co-founded the League for Programming Freedom. This has included software license agreements, non-disclosure agreements, activation keys, dongles, copy restriction, proprietary formats, as of 2016, he has received fifteen honorary doctorates and professorships. Stallman was born to Alice Lippman, a teacher, and Daniel Stallman. He was interested in computers at an age, when Stallman was a pre-teen at a summer camp. From 1967 to 1969, Stallman attended a Columbia University Saturday program for school students. Stallman was also a laboratory assistant in the biology department at Rockefeller University. Although he was interested in mathematics and physics, his professor at Rockefeller thought he showed promise as a biologist. His first experience with computers was at the IBM New York Scientific Center when he was in high school. He was hired for the summer in 1970, following his year of high school. He completed the task after a couple of weeks and spent the rest of the writing a text editor in APL. As a first-year student at Harvard University in fall 1970, Stallman was known for his performance in Math 55. He was happy, For the first time in my life, Stallman graduated from Harvard magna cum laude earning a bachelors degree in Physics in 1974. Stallman considered staying on at Harvard, but instead he decided to enroll as a student at MIT. He pursued a doctorate in physics for one year, but left that program to focus on his programming at the MIT AI Laboratory
26.
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
27.
Unix shell
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A Unix shell is a command-line interpreter or shell that provides a traditional Unix-like command line user interface. Users direct the operation of the computer by entering commands as text for a command line interpreter to execute, users typically interact with a Unix shell using a terminal emulator, however, direct operation via serial hardware connections, or networking session, are common for server systems. All Unix shells provide filename wildcarding, piping, here documents, command substitution, variables and control structures for condition-testing, the most generic sense of the term shell means any program that users employ to type commands. In Unix-like operating systems, users typically have many choices of command-line interpreters for interactive sessions, when a user logs in to the system interactively, a shell program is automatically executed for the duration of the session. The Unix shell is both a command language as well as a scripting programming language, and is used by the operating system as the facility to control the execution of the system. Shells created for operating systems often provide similar functionality. On hosts with a system, like macOS, some users may never use the shell directly. However, some vendors have replaced the traditional shell-based startup system with different approaches. The first Unix shell was the Thompson shell, sh, written by Ken Thompson at Bell Labs and distributed with Versions 1 through 6 of Unix, though not in current use, it is still available as part of some Ancient UNIX Systems. It was modeled after the Multics shell, itself modeled after the RUNCOM program Louis Pouzin showed to the Multics Team, the rc suffix on some Unix configuration files, is a remnant of the RUNCOM ancestry of Unix shells. The PWB shell or Mashey shell, sh, was a version of the Thompson shell, augmented by John Mashey and others and distributed with the Programmers Workbench UNIX. It focused on making shell programming practical, especially in large shared computing centers and it added shell variables, user-executable shell scripts, and interrupt-handling. Control structures were extended from if/goto to if/then/else/endif, switch/breaksw/endsw, as shell programming became widespread, these external commands were incorporated into the shell itself for performance. But the most widely distributed and influential of the early Unix shells were the Bourne shell, both shells have been used as the coding base and model for many derivative and work-alike shells with extended feature sets. The Bourne shell, sh, was a rewrite by Stephen Bourne at Bell Labs. The language, including the use of a keyword to mark the end of a block, was influenced by ALGOL68. Traditionally, the Bourne shell program name is sh and its path in the Unix file system hierarchy is /bin/sh, but a number of compatible work-alikes are also available with various improvements and additional features. The sh of FreeBSD, NetBSD are based on ash that has enhanced to be POSIX conformant for the occasion
28.
Compiler
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A compiler is a computer program that transforms source code written in a programming language into another computer language, with the latter often having a binary form known as object code. The most common reason for converting source code is to create an executable program, the name compiler is primarily used for programs that translate source code from a high-level programming language to a lower level language. If the compiled program can run on a computer whose CPU or operating system is different from the one on which the compiler runs, more generally, compilers are a specific type of translator. While all programs that take a set of programming specifications and translate them, a program that translates from a low-level language to a higher level one is a decompiler. A program that translates between high-level languages is called a source-to-source compiler or transpiler. A language rewriter is usually a program that translates the form of expressions without a change of language, the term compiler-compiler is sometimes used to refer to a parser generator, a tool often used to help create the lexer and parser. A compiler is likely to many or all of the following operations, lexical analysis, preprocessing, parsing, semantic analysis, code generation. Program faults caused by incorrect compiler behavior can be difficult to track down and work around, therefore. Software for early computers was written in assembly language. The notion of a high level programming language dates back to 1943, no actual implementation occurred until the 1970s, however. The first actual compilers date from the 1950s, identifying the very first is hard, because there is subjectivity in deciding when programs become advanced enough to count as the full concept rather than a precursor. 1952 saw two important advances. Grace Hopper wrote the compiler for the A-0 programming language, though the A-0 functioned more as a loader or linker than the notion of a full compiler. Also in 1952, the first autocode compiler was developed by Alick Glennie for the Mark 1 computer at the University of Manchester and this is considered by some to be the first compiled programming language. The FORTRAN team led by John Backus at IBM is generally credited as having introduced the first unambiguously complete compiler, COBOL was an early language to be compiled on multiple architectures, in 1960. In many application domains the idea of using a higher level language quickly caught on, because of the expanding functionality supported by newer programming languages and the increasing complexity of computer architectures, compilers have become more complex. Early compilers were written in assembly language, the first self-hosting compiler – capable of compiling its own source code in a high-level language – was created in 1962 for the Lisp programming language by Tim Hart and Mike Levin at MIT. Since the 1970s, it has become practice to implement a compiler in the language it compiles
29.
Massachusetts Institute of Technology
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The Massachusetts Institute of Technology is a private research university in Cambridge, Massachusetts, often cited as one of the worlds most prestigious universities. Researchers worked on computers, radar, and inertial guidance during World War II, post-war defense research contributed to the rapid expansion of the faculty and campus under James Killian. The current 168-acre campus opened in 1916 and extends over 1 mile along the bank of the Charles River basin. The Institute is traditionally known for its research and education in the sciences and engineering, and more recently in biology, economics, linguistics. Air Force and 6 Fields Medalists have been affiliated with MIT, the school has a strong entrepreneurial culture, and the aggregated revenues of companies founded by MIT alumni would rank as the eleventh-largest economy in the world. In 1859, a proposal was submitted to the Massachusetts General Court to use newly filled lands in Back Bay, Boston for a Conservatory of Art and Science, but the proposal failed. A charter for the incorporation of the Massachusetts Institute of Technology, Rogers, a professor from the University of Virginia, wanted to establish an institution to address rapid scientific and technological advances. The Rogers Plan reflected the German research university model, emphasizing an independent faculty engaged in research, as well as instruction oriented around seminars, two days after the charter was issued, the first battle of the Civil War broke out. After a long delay through the war years, MITs first classes were held in the Mercantile Building in Boston in 1865, in 1863 under the same act, the Commonwealth of Massachusetts founded the Massachusetts Agricultural College, which developed as the University of Massachusetts Amherst. In 1866, the proceeds from sales went toward new buildings in the Back Bay. MIT was informally called Boston Tech, the institute adopted the European polytechnic university model and emphasized laboratory instruction from an early date. Despite chronic financial problems, the institute saw growth in the last two decades of the 19th century under President Francis Amasa Walker. Programs in electrical, chemical, marine, and sanitary engineering were introduced, new buildings were built, the curriculum drifted to a vocational emphasis, with less focus on theoretical science. The fledgling school still suffered from chronic financial shortages which diverted the attention of the MIT leadership, during these Boston Tech years, MIT faculty and alumni rebuffed Harvard University president Charles W. Eliots repeated attempts to merge MIT with Harvard Colleges Lawrence Scientific School. There would be at least six attempts to absorb MIT into Harvard, in its cramped Back Bay location, MIT could not afford to expand its overcrowded facilities, driving a desperate search for a new campus and funding. Eventually the MIT Corporation approved an agreement to merge with Harvard, over the vehement objections of MIT faculty, students. However, a 1917 decision by the Massachusetts Supreme Judicial Court effectively put an end to the merger scheme, the neoclassical New Technology campus was designed by William W. Bosworth and had been funded largely by anonymous donations from a mysterious Mr. Smith, starting in 1912. In January 1920, the donor was revealed to be the industrialist George Eastman of Rochester, New York, who had invented methods of production and processing
30.
4.4BSD
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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
31.
Mach (kernel)
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Mach is a kernel developed at Carnegie Mellon University to support operating system research, primarily distributed and parallel computing. Mach is often mentioned as one of the earliest examples of a microkernel, however, not all versions of Mach are microkernels. Machs derivatives are the basis of the operating system kernels in GNU Hurd. The project at Carnegie Mellon ran from 1985 to 1994, ending with Mach 3.0, Mach was developed as a replacement for the kernel in the BSD version of Unix, so no new operating system would have to be designed around it. Experimental research on Mach appears to have ended, although Mach and these include NeXTSTEP and OpenStep, upon which macOS is based—all using the XNU operating system kernel which incorporates an earlier, non-microkernel, Mach as a major component. The Mach virtual memory management system was adopted in 4. 4BSD by the BSD developers at CSRG. Mach is the successor to Carnegie Mellons Accent kernel. The lead developer on the Mach project, Richard Rashid, has been working at Microsoft since 1991 in various top-level positions revolving around the Microsoft Research division. Another of the original Mach developers, Avie Tevanian, was head of software at NeXT. Rashid liked Giuses spelling Mach so much that it prevailed, a key concept in the original Unix operating system was the idea of a pipe. A pipe was an abstraction that allowed data to be moved from program to program using the command line, using pipes, users could link together multiple programs to complete tasks, feeding data through several small programs in turn. Pipes were built on the underlying input/output system and this system was, in turn, based on a model where drivers were expected to periodically block while they waited for tasks to complete. For instance, a driver might send a line of text to a line printer. In this case, the driver would indicate that it was blocked, in the pipes system the limited resource was memory, and when one program filled the memory assigned to the pipe, it would naturally block. Normally this would cause the program to run, emptying the pipe out again. However, the implementation of pipes as memory buffers meant data was being copied from program to program and this made the pipe concept unsuitable for tasks where quick turnaround or low latency was needed, as is the case in most device drivers. The operating system kernel and most core functionality was instead written as a large program. As the operating system added new functionality, the size and complexity of the kernel grew, Unix pipes offered a conceptual system that could be used to build arbitrarily complex solutions out of small interacting programs
32.
Carnegie Mellon University
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Carnegie Mellon University is a private research university in Pittsburgh, Pennsylvania. Founded in 1900 by Andrew Carnegie as the Carnegie Technical Schools, in 1967, the Carnegie Institute of Technology merged with the Mellon Institute of Industrial Research to form Carnegie Mellon University. The universitys 140-acre main campus is 3 miles from Downtown Pittsburgh, john Heinz III College of Information Systems and Public Policy, and the School of Computer Science. The university also has campuses in Qatar and Silicon Valley, with degree-granting programs in six continents, Carnegie Mellon consistently ranks in the top 25 in the national U. S. News & World Report rankings. It is home to the world’s first degree-granting Robotics and Drama programs, the university spent $242 million on research in 2015. Carnegie Mellon counts 13,650 students from 114 countries, over 100,000 living alumni, Carnegies vision was to open a vocational training school for the sons and daughters of working-class Pittsburghers. Carnegie was inspired for the design of his school by the Pratt Institute in Brooklyn, in 1912 the institution changed its name to Carnegie Institute of Technology and began offering four-year degrees. The Mellon Institute of Industrial Research was founded in 1913 by banker and industrialist brothers Andrew, Mellon in honor of their father, Thomas Mellon, the patriarch of the Mellon family. The Institute began as an organization which performed work for government. In 1927, the Mellon Institute incorporated as an independent nonprofit, in 1938, the Mellon Institutes iconic building was completed and it moved to its new, and current, location on Fifth Avenue. In 1967, with support from Paul Mellon, Carnegie Tech merged with the Mellon Institute of Industrial Research to become Carnegie Mellon University, Carnegie Mellons coordinate womens college, the Margaret Morrison Carnegie College closed in 1973 and merged its academic programs with the rest of the university. The industrial research mission of the Mellon Institute survived the merger as the Carnegie Mellon Research Institute and continued doing work on contract to industry, CMRI closed in 2001 and its programs were subsumed by other parts of the university or spun off into independent entities. Carnegie Mellons 140-acre main campus is three miles from downtown Pittsburgh, between Schenley Park and the Squirrel Hill, Shadyside, and Oakland neighborhoods, Carnegie Mellon is bordered to the west by the campus of the University of Pittsburgh. Carnegie Mellon owns 81 buildings in the Oakland and Squirrel Hill neighborhoods of Pittsburgh, for decades the center of student life on campus was Skibo Hall, the Universitys student union. Built in the 1950s, Skibo Halls design was typical of Mid-Century Modern architecture, the original Skibo was razed in the summer of 1994 and replaced by a new student union that is fully wi-fi enabled. Known as University Center, the building was dedicated in 1996, in 2014, Carnegie Mellon re-dedicated the University Center as the Cohon University Center in recognition of the eighth president of the university, Jared Cohon. A large grassy area known as the Cut forms the backbone of the campus, the Cut was formed by filling in a ravine with soil from a nearby hill that was leveled to build the College of Fine Arts building. The northwestern part of the campus was acquired from the United States Bureau of Mines in the 1980s, the sculpture was controversial for its placement, the general lack of input that the campus community had, and its aesthetic appeal
33.
Linux distribution
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A Linux distribution is an operating system made from a software collection, which is based upon the Linux kernel and, often, a package management system. A typical Linux distribution comprises a Linux kernel, GNU tools and libraries, additional software, documentation, a system, a window manager. Most of the software is free and open-source software made available both as compiled binaries and in source code form, allowing modifications to the original software. Usually, Linux distributions optionally include some proprietary software that may not be available in source code form, the software is usually adapted to the distribution and then packaged into software packages by the distributions maintainers. The software packages are available online in so-called repositories, which are storage locations usually distributed around the world, almost six hundred Linux distributions exist, with close to five hundred out of those in active development. There are commercially backed distributions, such as Fedora, openSUSE and Ubuntu, most distributions come ready to use and pre-compiled for a specific instruction set, while some distributions are distributed mostly in source code form and compiled locally during installation. Linus Torvalds developed the Linux kernel and distributed its first version,0.01, since the installation procedure was complicated, especially in the face of growing amounts of available software, distributions sprang up to simplify this. Early distributions included the following, H. J, the SLS distribution was not well maintained, so in July 1993 a new distribution, called Slackware and based on SLS, was released by Patrick Volkerding. Also dissatisfied with SLS, Ian Murdock set to create a distribution by founding Debian. Most early adopters were familiar with Unix from work or school and they embraced Linux distributions for their low cost, and availability of the source code for most or all of the software included. Originally, the distributions were simply a convenience, but later became the usual choice even for Unix or Linux experts. To date, Linux has become popular in server and embedded devices markets than in the desktop market. For example, Linux is used on over 50% of web servers, many Linux distributions provide an installation system akin to that provided with other modern operating systems. Distributions are normally segmented into packages, each package contains a specific application or service. Examples of packages are a library for handling the PNG image format, the package is typically provided as compiled code, with installation and removal of packages handled by a package management system rather than a simple file archiver. Each package intended for such a PMS contains meta-information such as a description, version. Although Linux distributions typically contain much more software than proprietary operating systems, an example would be a newer version of a software application than that supplied with a distribution, or an alternative to that chosen by the distribution. If the additional software is distributed in form, this approach requires local compilation
34.
GNU/Linux naming controversy
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GNU/Linux is a term promoted by the Free Software Foundation and its founder Richard Stallman. In 1983, Richard Stallman, founder of the Free Software Foundation, set forth plans of a complete Unix-like operating system, called GNU, composed entirely of free software. In September of that year, Stallman published a manifesto in Dr. Dobbs Journal detailing his new project publicly, Software development work began in January 1984. By 1991, the GNU mid-level portions of the system were almost complete, and the upper level could be supplied by the X Window System. The GNU kernel was called GNU Hurd, the Hurd followed an ambitious design which proved unexpectedly difficult to implement and has only been marginally usable. Independently, in 1991, Linus Torvalds released the first version of the Linux kernel, early Linux developers ported GNU code, including the GNU C Compiler, to the kernel. The free software community adopted the use of the Linux kernel as the kernel for the GNU operating system. This work filled the gaps in providing a completely free operating system. Over the next few years, several suggestions arose for naming operating systems using the Linux kernel, in 1992, the Yggdrasil Linux distribution adopted the name Linux/GNU/X. In Usenet and mailing-list discussions, one can find usages of GNU/Linux as early as 1992, gNUs June 1994 Bulletin describes Linux as a free Unix system for 386 machines, but the January 1995 Bulletin switched to the term GNU/Linux instead. Stallmans and the FSFs efforts to include GNU in the name started around 1994 and he later used GNU/Linux exclusively, and the essay was superseded by Stallmans 1997 essay, Linux and the GNU project. Desktop- and server-based distributions use GNU components such as the GNU C Library, GNU Core Utilities, and bash. In a 2002 analysis of the code for Red Hat Linux 7.1, a typical Linux distribution. Later, a 2011 analysis of Ubuntus Natty release main repository found that 8% to 13% of it consisted of GNU components, determining exactly what constitutes the operating system per se is a matter of continuing debate. A system running μClinux is likely to substitute uClibc for glibc, Googles Linux-based Android operating system does not use any GNU components or libraries, replacing glibc with Googles own BSD-based Bionic C library. The FSF agrees that GNU/Linux is not a name for these systems. There are also systems that use a GNU userspace and/or C library on top of a non-Linux kernel, but we dont think that is the right way to consider the question. The GNU Project was not, is not, a project to develop specific software packages, many people have made major contributions to the free software in the system, and they all deserve credit
35.
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
36.
Debian
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The Debian Project was first announced in 1993 by Ian Murdock, Debian 0.01 was released on September 15,1993, and the first stable release was made in 1996. The Debian stable release branch is one of the most popular for personal computers and network servers, new distributions are updated continually, and the next candidate is released after a time-based freeze. As one of the earliest Operating Systems based on the Linux kernel and this decision drew the attention and support of the Free Software Foundation, which sponsored the project for one year from November 1994 to November 1995. Upon the ending of the sponsorship, the Debian Project formed the non-profit organisation Software in the Public Interest, while Debians main port, Debian GNU/Linux, uses the Linux kernel, other ports exist based on BSD kernels and the HURD microkernel. All use the GNU userland and the GNU C library, Debian has access to online repositories that contain over 50,000 software packages making it one of the largest software compilations. Debian officially contains only free software, but non-free software can be downloaded from the Debian repositories, Debian includes popular free programs such as LibreOffice, Firefox web browser, Evolution mail, K3b disc burner, VLC media player, GIMP image editor, and Evince document viewer. Debian is a choice for web servers. Debian supports Linux officially, offered kFreeBSD for version 7 but not 8, GNU/kFreeBSD was released as a technology preview for IA-32 and x86-64 architectures, and lacked the amount of software available in Debians Linux distribution. Official support for kFreeBSD was removed for version 8, which did not provide a kFreeBSD-based distribution, several flavors of the Linux kernel exist for each port. For example, the port has flavors for IA-32 PCs supporting Physical Address Extension and real-time computing, for older PCs. The Linux kernel does not officially contain firmware without sources, although such firmware is available in non-free packages, Debian offers DVD and CD images for installation that can be downloaded using BitTorrent or jigdo. Physical disks can also be bought from retailers, Debian offers different network installation methods. A minimal install of Debian is available via the netinst CD, whereby Debian is installed with just a base, another option is to boot the installer from the network. Installation images are hybrid on some architectures and can be used to create a bootable USB drive, the default bootstrap loader is GNU GRUB version 2, though the package name is simply grub, while version 1 was renamed to grub-legacy. This conflicts with e. g. Fedora, where grub version 2 is named grub2, the default desktop may be chosen from the DVD boot menu among GNOME, KDE Software Compilation, Xfce and LXDE, and from special disc 1 CDs. Debian offers CD images specifically built for GNOME, KDE Software Compilation, Xfce, MATE is officially supported, while Cinnamon support was added with Debian 8.0 Jessie. Less common window managers such as Enlightenment, Openbox, Fluxbox, IceWM, Window Maker, the default desktop environment of version 7.0 Wheezy was temporarily switched to Xfce, because GNOME3 did not fit on the first CD of the set. The default for the version 8.0 Jessie was changed again to Xfce in November 2013, Debian releases live install images for CDs, DVDs and USB thumb drives, for IA-32 and x86-64 architectures, and with a choice of desktop environments
37.
Debian GNU/Hurd
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Debian GNU/Hurd is the Debian projects distribution of the GNU operating system, using the GNU Hurd microkernel. Debian GNU/Hurd has been in development since 1998, and made a release in May 2013. The Debian GNU/Hurd developers were hoping to be able to release it with Debian Wheezy in 2013, however, Hurd is not yet an official Debian release, and is maintained and developed as an unofficial port. According to the GNU/Hurd compatibility guide, the current version is compatible with laptops, Debian GNU/Hurd is distributed as an installer CD or ready-to-run virtual disk image. The CD uses the IA-32 architecture, making it compatible with IA-32, the current version of Debian GNU/Hurd is 2017, published in January 2017. Arch Hurd Debian GNU/kFreeBSD GNU Hurd Hurd variants Multiboot Specification X Window System Debian GNU/Hurd home page Install CD images GNU/Hurd Plans For A Future With USB, SATA, 64-Bit
38.
IBM PC compatible
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IBM PC compatible computers are those similar to the original IBM PC, XT, and AT, able to run the same software and support the same expansion cards as those. Such computers used to be referred to as PC clones, or IBM clones, Columbia Data Products built the first clone of the IBM personal computer by a clean room implementation of its BIOS. Early IBM PC compatibles used the computer bus as the original PC. The IBM AT compatible bus was named the Industry Standard Architecture bus by manufacturers of compatible computers. The term IBM PC compatible is now a historical description only, only the Apple Macintosh classic Mac OS and macOS kept significant market share without compatibility with the IBM personal computer, so consumers are typically identified as being a PC or Mac user. IBM decided in 1980 to market a low-cost single-user computer as quickly as possible in response to Apple Computers success in the microcomputer market. On 12 August 1981, the first IBM PC went on sale, there were three operating systems available for it. The least expensive and most popular was PC DOS made by Microsoft, in a crucial concession, IBMs agreement allowed Microsoft to sell its own version, MS-DOS, for non-IBM computers. The only component of the original PC architecture exclusive to IBM was the BIOS and this software would run on any machine using MS-DOS or PC-DOS. Software that directly addressed the hardware instead of making standard calls was faster, however, software addressing IBM PC hardware in this way would not run on MS-DOS machines with different hardware. The 808x computer marketplace rapidly excluded all machines which were not hardware-, the 640 KB barrier on conventional system memory available to MS-DOS is a legacy of that period, other non-clone machines, while subject to a limit, could exceed 640 kB. Rumors of lookalike, compatible computers, created without IBMs approval, by June 1983 PC Magazine defined PC clone as a computer accommodate the user who takes a disk home from an IBM PC, walks across the room, and plugs it into the foreign machine. Because of a shortage of IBM PCs that year, many customers purchased clones instead, Columbia Data Products produced the first computer more or less compatible to the IBM PC standard during June 1982, soon followed by Eagle Computer. Compaq announced its first IBM PC compatible in November 1982, the Compaq Portable, the Compaq was the first sewing machine-sized portable computer that was essentially 100% PC-compatible. The company could not copy the BIOS directly as a result of the decision in Apple v. Franklin. Each computer would have its own Original Equipment Manufacturer version of MS-DOS, any software written for MS-DOS would operate on any MS-DOS computer, despite variations in hardware design. This expectation seemed reasonable in the marketplace of the time. Until then Microsoft was based primarily on computer languages such as BASIC, the established small system operating software was CP/M from Digital Research which was in use both at the hobbyist level and by the more professional of those using microcomputers
39.
Google Summer of Code
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The program is open to university students aged 18 or over. The idea for the Summer of Code came directly from Googles founders, Sergey Brin, from 2007 until 2009 Leslie Hawthorn, who has been involved in the project since 2006, was the program manager. From 2010 until 2015, Carol Smith was the program manager, in 2016, Stephanie Taylor took over management of the program. The program invites students who meet their eligibility criteria to post at most 5 applications that detail the project they wish to work on. These applications are evaluated by the corresponding mentoring organization. Every participating organization must provide mentors for each of the ideas received. The mentors then rank the applications and decide among themselves which proposals to accept, in the event of a single student being marked in more than one organization, Google mediates between all the involved organizations and decides who gets that student. The other mentoring organization then unmarks the student and marks a new proposal for acceptance, or gives their slot back to the pool, Google has published the top 15 schools of current year for the period 2005–2016. The list is as follows, In 2005, more than 8,740 project proposals were submitted for the 200 available student positions, due to the overwhelming response, Google expanded the program to 419 positions. The mentoring organizations were responsible for reviewing and selecting proposals, many projects were continued past summer, even though the SOC period was over, and some changed direction as they developed. For the first Summer of Code, Google was criticized for not giving sufficient time to open source organizations so they could plan projects for the Summer of Code. Despite these criticisms there were 41 organizations involved, including FreeBSD, Apache, KDE, Ubuntu, Blender, Mozdev, according to a blog post by Chris DiBona, Googles open source program manager, something like 30 percent of the students stuck with their groups past SoC. Mozilla developer Gervase Markham also commented that none of the 10 Google-sponsored Mozilla projects survived after the event. In 2006, around 6,000 applications were submitted, less than the year because all applicants were required to have Google Accounts. Google and most mentors are also of the opinion that the proposals were of higher quality than 2005s applications. Also, the number of participating organizations more than doubled to 102, in addition to the organizations that participated in 2005, organizations such as Debian, GNU, Gentoo, Adium, PHP, and ReactOS participated in 2006. Google had decided to sponsor around 600 projects, the student application deadline was extended until 2006-05-09, at 11,00 PDT. Although the results were to be declared by 5,00 PM PDT, Google allows one student to undertake only one project as part of the program
40.
GNU Guix
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GNU Guix is a package manager for the GNU System. It is based on the Nix package manager with Guile Scheme APIs, the GNU Project announced on November 2012 the first release of GNU Guix, a functional package manager based on Nix that provides, among other things, Guile Scheme APIs. The project was started on June 2012 by Ludovic Courtès, one of the GNU Guile hackers, on August 20,2015, it was announced that Guix had been ported to GNU Hurd, making it the first native package manager on the Hurd. The Guix project also develops the Guix System Distribution, a complete installable GNU system using the Linux-libre kernel and GNU Shepherd init system
