1.
Xfce
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Xfce is a free and open-source desktop environment for Unix and Unix-like operating systems, such as Linux, Solaris, and BSD. Xfce aims to be fast and lightweight, while still being visually appealing, Xfce embodies the traditional UNIX philosophy of modularity and re-usability. It consists of separately packaged parts that provide all functions of the desktop environment. Another priority of Xfce is adherence to standards, specifically those defined at freedesktop. org, like GNOME, Xfce is based on the GTK+ toolkit. It uses the Xfwm window manager, described below and its configuration is entirely mouse-driven, with the configuration files hidden from the casual user. Xfce does not feature any desktop animations, but Xfwm supports compositing, olivier Fourdan started the project in 1996 as a Linux version of the Common Desktop Environment, a Unix desktop environment that was initially proprietary and later released as free software. However, after a years of development and several major versions, Xfce has diverged from CDE. The name Xfce originally stood for XForms Common Environment, but since that time Xfce has been rewritten twice, the name survived, but it is no longer capitalized as XFCE, but rather as Xfce. The developers current stance is that the no longer stands for anything specific. It has been nicknamed Cholesterol Free Desktop Environment, another possibility X Freakin Cool Environment is suggested at Xfce Wiki. As a result, Xfce is currently an acronym that doesnt stand for anything, Xfce began as a simple project created with XForms. Olivier Fourdan released the program, which was just a simple taskbar, Fourdan continued developing the project and in 1998, Xfce 2 was released with the first version of Xfces window manager, Xfwm. He requested to have the project included in Red Hat Linux, Red Hat only accepted software that was open source and released under either a GPL or BSD compatible license, whereas, at the time, XForms was closed source and free only for personal use. For the same reason, Xfce was not in Debian before version 3, in March 1999 Fourdan began a complete rewrite of the project based on GTK+, a non-proprietary toolkit rising in popularity. The result was Xfce 3.0, licensed under the GPL, along with being based completely on free software, the project gained GTK+ drag-and-drop support, native language support, and improved configurability. Xfce was uploaded to SourceForge. net in February 2001, starting with version 3.8.1, in version 4.0.0, released 25 September 2003, Xfce was upgraded to use the GTK+2 libraries. Changes in 4.2.0 included a compositing manager for Xfwm which added support for transparency and drop shadows. In January 2007, Xfce 4.4.0 was released and this included the Thunar file manager, a replacement for Xffm
2.
Firefox
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Mozilla Firefox is a free and open-source web browser developed by the Mozilla Foundation and its subsidiary the Mozilla Corporation. Firefox was created in 2002, under the name Phoenix by the Mozilla community members who wanted a standalone rather than the Mozilla Application Suite bundle. Even during its phase, Firefox proved to be popular with its testers and was praised for its speed, security. Firefox was released in November 2004, and was successful with 60 million downloads within nine months. Firefox is considered the successor of Netscape Navigator, as the Mozilla community was created by Netscape in 1998 before their acquisition by AOL. Firefox usage grew to a peak of 32% at the end of 2009, usage then declined in competition with Google Chrome. As of January 2016, Firefox has between 9% and 16% of worldwide usage as a browser, making it the second most popular web browser. Firefox is still the most popular browser in Cuba, Eritrea, and Germany, with 85. 93%,79. 39%. It is also the most popular browser in many other African countries. According to Mozilla, as of December 2014 there were half a billion Firefox users around the world, the Firefox project began as an experimental branch of the Mozilla project by Dave Hyatt, Joe Hewitt, and Blake Ross. They believed the requirements of Netscapes sponsorship and developer-driven feature creep compromised the utility of the Mozilla browser. To combat what they saw as the Mozilla Suites software bloat, they created a stand-alone browser, on April 3,2003, the Mozilla Organization announced that they planned to change their focus from the Mozilla Suite to Firefox and Thunderbird. The community-driven SeaMonkey was formed and eventually replaced the Mozilla Application Suite in 2005, the Firefox project has undergone several name changes. Phoenix was renamed due to issues with Phoenix Technologies, the replacement name, Firebird. In response, the Mozilla Foundation stated that the browser would always bear the name Mozilla Firebird to avoid confusion, after further pressure, on February 9,2004, Mozilla Firebird became Mozilla Firefox. The name Firefox was said to be derived from a nickname of the red panda, for the abbreviation of Firefox, Mozilla prefers Fx or fx, though it is often abbreviated as FF. The Firefox project went through many versions before the version 1.0 was released on November 9,2004, search, which is a front end of Microsoft search engine Bing, by default in most localizations. Firefox Hello is scheduled to be removed in September 2016, functions can be added through add-ons created by third-party developers
3.
LibreOffice
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LibreOffice is a free and open source office suite, a project of The Document Foundation. It was forked from OpenOffice. org in 2010, which was a version of the earlier StarOffice. The LibreOffice suite comprises programs for processing, the creation and editing of spreadsheets, slideshows, diagrams and drawings, working with databases. It is available in 110 languages, LibreOffice uses the international ISO/IEC standard OpenDocument file format as its native format to save documents for all of its applications. LibreOffice also supports the file formats of most other major office suites, including Microsoft Office, LibreOffice is available for a variety of computing platforms, including Microsoft Windows, macOS, and Linux, as well as in the form of an online office suite. It is the office suite of most popular Linux distributions. It is the most actively developed free and open-source office suite, with approximately 50 times the development activity of Apache OpenOffice, between January 2011 and October 2011, LibreOffice was downloaded approximately 7.5 million times. The project claims 120 million unique downloading addresses from May 2011 to May 2015, excluding Linux distributions, the Document Foundation developers target LibreOffice for Microsoft Windows, Linux and macOS. Community ports for FreeBSD, NetBSD, OpenBSD and Mac OS X10.5 PowerPC receive support from contributors to those projects, Libreoffice is also installable on OpenIndiana via SFE. LibreOffice Online will allow for the use of LibreOffice through a web browser by using the element of HTML5. Development was announced at the first LibreOffice Conference in October 2011, LibreOffice announced a collaboration with Icewarp and Collabora to work on the cross-platform interface. A version of the software was shown in a September 2015 conference, on 15 December 2015, Collabora, in partnership with ownCloud, released a technical preview of Libreoffice Online branded as Collabora Online Development Edition. By October 2016, Collabora had released nine updates to CODE, in 2011, developers announced plans to port LibreOffice both to Android and to iOS. A beta version of a document viewer for Android 4.0 or newer was released in January 2015, In May 2015, in January 2015, a LibreOffice Impress remote app was unveiled for the Pebble smartwatch. A detailed 60-page report in June 2015 compared the progress of the LibreOffice project with its cousin project Apache OpenOffice and it showed that OpenOffice received about 10% of the improvements LibreOffice did in the period of time studied. LibreOffice can use the GStreamer multimedia framework in Linux to render multimedia content such as videos in Impress and they are also used on the toolbars and menus by default. LibreOffice also ships with a theme which looks native on GTK-based Linux distributions. It also renders fonts via Cairo on Linux distributions, this means that text in LibreOffice is rendered the same as the rest of the Linux desktop, LibreOffice has a feature similar to WordArt called Fontwork
4.
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
5.
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
6.
Berkeley Software Distribution
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Berkeley Software Distribution is a Unix operating system derivative developed and distributed by the Computer Systems Research Group of the University of California, Berkeley, from 1977 to 1995. Today the term BSD is often used non-specifically to refer to any of the BSD descendants which together form a branch of the family of Unix-like operating systems, operating systems derived from the original BSD code remain actively developed and widely used. Historically, BSD has been considered a branch of Unix, Berkeley Unix, because it shared the initial codebase, in the 1980s, BSD was widely adopted by vendors of workstation-class systems in the form of proprietary Unix variants such as DEC ULTRIX and Sun Microsystems SunOS. This can be attributed to the ease with which it could be licensed, FreeBSD, OpenBSD, NetBSD, Darwin, and PC-BSD. The earliest distributions of Unix from Bell Labs in the 1970s included the source code to the system, allowing researchers at universities to modify. A larger PDP-11/70 was installed at Berkeley the following year, using money from the Ingres database project, also in 1975, Ken Thompson took a sabbatical from Bell Labs and came to Berkeley as a visiting professor. He helped to install Version 6 Unix and started working on a Pascal implementation for the system, graduate students Chuck Haley and Bill Joy improved Thompsons Pascal and implemented an improved text editor, ex. Other universities became interested in the software at Berkeley, and so in 1977 Joy started compiling the first Berkeley Software Distribution, 1BSD was an add-on to Version 6 Unix rather than a complete operating system in its own right. Some thirty copies were sent out, some 75 copies of 2BSD were sent out by Bill Joy. 2. 9BSD from 1983 included code from 4. 1cBSD, the most recent release,2. 11BSD, was first issued in 1992. As of 2008, maintenance updates from volunteers are still continuing, a VAX computer was installed at Berkeley in 1978, but the port of Unix to the VAX architecture, UNIX/32V, did not take advantage of the VAXs virtual memory capabilities. 3BSD was also alternatively called Virtual VAX/UNIX or VMUNIX, and BSD kernel images were normally called /vmunix until 4. 4BSD, 4BSD offered a number of enhancements over 3BSD, notably job control in the previously released csh, delivermail, reliable signals, and the Curses programming library. In a 1985 review of BSD releases, John Quarterman et al, many installations inside the Bell System ran 4. 1BSD. 4. 1BSD was a response to criticisms of BSDs performance relative to the dominant VAX operating system, the 4. 1BSD kernel was systematically tuned up by Bill Joy until it could perform as well as VMS on several benchmarks. Back at Bell Labs,4. 1cBSD became the basis of the 8th Edition of Research Unix, to guide the design of 4. The committee met from April 1981 to June 1983, apart from the Fast File System, several features from outside contributors were accepted, including disk quotas and job control. Sun Microsystems provided testing on its Motorola 68000 machines prior to release, the official 4. 2BSD release came in August 1983. On a lighter note, it marked the debut of BSDs daemon mascot in a drawing by John Lasseter that appeared on the cover of the printed manuals distributed by USENIX
7.
Open-source model
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Open-source software may be developed in a collaborative public manner. According to scientists who studied it, open-source software is a prominent example of open collaboration, a 2008 report by the Standish Group states that adoption of open-source software models has resulted in savings of about $60 billion per year to consumers. In the early days of computing, programmers and developers shared software in order to learn from each other, eventually the open source notion moved to the way side of commercialization of software in the years 1970-1980. In 1997, Eric Raymond published The Cathedral and the Bazaar and this source code subsequently became the basis behind SeaMonkey, Mozilla Firefox, Thunderbird and KompoZer. Netscapes act prompted Raymond and others to look into how to bring the Free Software Foundations free software ideas, the new term they chose was open source, which was soon adopted by Bruce Perens, publisher Tim OReilly, Linus Torvalds, and others. The Open Source Initiative was founded in February 1998 to encourage use of the new term, a Microsoft executive publicly stated in 2001 that open source is an intellectual property destroyer. I cant imagine something that could be worse than this for the software business, IBM, Oracle, Google and State Farm are just a few of the companies with a serious public stake in todays competitive open-source market. There has been a significant shift in the corporate philosophy concerning the development of FOSS, the free software movement was launched in 1983. In 1998, a group of individuals advocated that the free software should be replaced by open-source software as an expression which is less ambiguous. Software developers may want to publish their software with an open-source license, the Open Source Definition, notably, presents an open-source philosophy, and further defines the terms of usage, modification and redistribution of open-source software. Software licenses grant rights to users which would otherwise be reserved by law to the copyright holder. Several open-source software licenses have qualified within the boundaries of the Open Source Definition, the open source label came out of a strategy session held on April 7,1998 in Palo Alto in reaction to Netscapes January 1998 announcement of a source code release for Navigator. They used the opportunity before the release of Navigators source code to clarify a potential confusion caused by the ambiguity of the free in English. Many people claimed that the birth of the Internet, since 1969, started the open source movement, the Free Software Foundation, started in 1985, intended the word free to mean freedom to distribute and not freedom from cost. Since a great deal of free software already was free of charge, such software became associated with zero cost. The Open Source Initiative was formed in February 1998 by Eric Raymond and they sought to bring a higher profile to the practical benefits of freely available source code, and they wanted to bring major software businesses and other high-tech industries into open source. Perens attempted to open source as a service mark for the OSI. The Open Source Initiatives definition is recognized by governments internationally as the standard or de facto definition, OSI uses The Open Source Definition to determine whether it considers a software license open source
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.
Package manager
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A package manager deals with packages, distributions of software and data in archive files. Packages contain metadata, such as the name, description of its purpose, version number, vendor, checksum. Upon installation, metadata is stored in a package database. Package managers typically maintain a database of software dependencies and version information to prevent software mismatches and they work closely with software repositories, binary repository managers, and app stores. Package managers are designed to eliminate the need for manual installs, a software package is an archive file containing a computer program as well as necessary metadata for its deployment. The computer program can be in source code that has to be compiled, Package metadata include package description, package version, and dependencies. Package managers are charged with the task of finding, installing, maintaining or uninstalling software packages upon the users command, in these systems, complex relationships between different packages requiring different versions of libraries results in a challenge colloquially known as dependency hell. On Microsoft Windows systems, this is also called DLL hell when working with dynamically linked libraries, good package management is vital on these systems. System administrators may install and maintain software using other than package management software. For example, an administrator may download unpackaged source code, compile it. This may cause the state of the system to fall out of synchronization with the state of the package managers database. The local administrator will be required to take measures, such as manually managing some dependencies or integrating the changes into the package manager. There are tools available to ensure that locally compiled packages are integrated with the package management, particularly troublesome with software upgrades are upgrades of configuration files. There are exceptions to this that usually apply to kernel configuration, problems can be caused if the format of configuration files changes. For instance, if the old configuration file does not explicitly disable new options that should be disabled, some package managers, such as Debians dpkg, allow configuration during installation. In other situations, it is desirable to install packages with the configuration and then overwrite this configuration, for instance. This kind of pre-configured installation is also supported by dpkg, to give users more control over the kinds of software that they are allowing to be installed on their system, software is often downloaded from a number of software repositories. This process is called version pinning
10.
Pkgsrc
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Pkgsrc is a package management system for Unix-like operating systems. It was forked from the FreeBSD ports collection in 1997 as the package management system for NetBSD. Since then it has evolved independently, in 1999, support for Solaris was added, dragonFly BSD, from release 1.4 to 3.4, used pkgsrc as its official packaging system. MINIX3 and the Dracolinux distribution both include pkgsrc in their main releases, there are multiple ways to install programs using pkgsrc. The pkgsrc bootstrap contains a traditional ports collection that utilizes a series of makefiles to compile software from source, another method is to install pre-built binary packages via the pkg_add and pkg_delete tools. It now supports around 23 operating systems, including AIX, various BSD derivatives, HP-UX, IRIX, Linux, macOS, Solaris, and QNX. Official website A web interface for pkgsrc pkgsrc-wip – a project to get more people involved with pkgsrc pkgsrcCon
11.
DEC Alpha
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Alpha was implemented in microprocessors originally developed and fabricated by DEC. These microprocessors were most prominently used in a variety of DEC workstations and servers, several third-party vendors also produced Alpha systems, including PC form factor motherboards. Operating systems that supported Alpha included OpenVMS, Tru64 UNIX, Windows NT, Linux, BSD UNIX, Plan 9 from Bell Labs, as well as the L4Ka, the Alpha architecture was sold, along with most parts of DEC, to Compaq in 1998. Alpha was born out of an earlier RISC project named PRISM, PRISM was intended to be a flexible design, supporting both Unix-like applications, as well as Digitals existing VMS programs from the VAX after minor conversion. A new Unix-like operating system known as Mica would run applications natively, during development, the Palo Alto design team were working on a Unix-only workstation that originally included the PRISM. DEC management doubted the need to produce a new architecture to replace their existing VAX and DECstation lines. By the time of cancellation, however, second-generation RISC chips were offering much better price/performance ratios than the VAX lineup and it was clear a third generation would completely outperform the VAX in all ways, not just on cost. Another study was started to see if a new RISC architecture could be defined that could support the VMS operating system. The new design used most of the basic PRISM concepts, but was re-tuned to allow VMS and VMS programs to run at speed with no conversion at all. The decision was made to upgrade the design to a full 64-bit implementation from PRISMs 32-bit. Eventually that new architecture became Alpha, the primary Alpha instruction set architects were Richard L. Sites and Richard T. Witek. The PRISMs Epicode was developed into the Alphas PALcode, providing an interface to platform-. The main contribution of Alpha to the industry, and the main reason for its performance, was not so much the architecture. At that time, the industry was dominated by automated design. The chip designers at Digital continued pursuing sophisticated manual circuit design in order to deal with the overly complex VAX architecture and these chips caused a renaissance of custom circuit design within the microprocessor design community. Originally, the Alpha processors were designated the DECchip 21x64 series, the first two digits,21 signifies the 21st century, and the last two digits,64 signifies 64 bits. The Alpha was designed as 64-bit from the start and there is no 32-bit version, the middle digit corresponded to the generation of the Alpha architecture. The first few generations of the Alpha chips were some of the most innovative of their time, the first version, the Alpha 21064 or EV4, was the first CMOS microprocessor whose operating frequency rivalled higher-powered ECL minicomputers and mainframes
12.
ARM architecture
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ARM, originally Acorn RISC Machine, later Advanced RISC Machine, is a family of reduced instruction set computing architectures for computer processors, configured for various environments. It also designs cores that implement this instruction set and licenses these designs to a number of companies that incorporate those core designs into their own products, a RISC-based computer design approach means processors require fewer transistors than typical complex instruction set computing x86 processors in most personal computers. This approach reduces costs, heat and power use and these characteristics are desirable for light, portable, battery-powered devices—including smartphones, laptops and tablet computers, and other embedded systems. For supercomputers, which large amounts of electricity, ARM could also be a power-efficient solution. ARM Holdings periodically releases updates to architectures and core designs, some older cores can also provide hardware execution of Java bytecodes. The ARMv8-A architecture, announced in October 2011, adds support for a 64-bit address space, with over 100 billion ARM processors produced as of 2017, ARM is the most widely used instruction set architecture in terms of quantity produced. Currently, the widely used Cortex cores, older classic cores, the British computer manufacturer Acorn Computers first developed the Acorn RISC Machine architecture in the 1980s to use in its personal computers. Its first ARM-based products were coprocessor modules for the BBC Micro series of computers, according to Sophie Wilson, all the tested processors at that time performed about the same, with about a 4 Mbit/second bandwidth. After testing all available processors and finding them lacking, Acorn decided it needed a new architecture, inspired by white papers on the Berkeley RISC project, Acorn considered designing its own processor. Wilson developed the set, writing a simulation of the processor in BBC BASIC that ran on a BBC Micro with a 6502 second processor. This convinced Acorn engineers they were on the right track, Wilson approached Acorns CEO, Hermann Hauser, and requested more resources. Hauser gave his approval and assembled a team to implement Wilsons model in hardware. The official Acorn RISC Machine project started in October 1983 and they chose VLSI Technology as the silicon partner, as they were a source of ROMs and custom chips for Acorn. Wilson and Furber led the design and they implemented it with a similar efficiency ethos as the 6502. A key design goal was achieving low-latency input/output handling like the 6502, the 6502s memory access architecture had let developers produce fast machines without costly direct memory access hardware. The first samples of ARM silicon worked properly when first received and tested on 26 April 1985, Wilson subsequently rewrote BBC BASIC in ARM assembly language. The in-depth knowledge gained from designing the instruction set enabled the code to be very dense, the original aim of a principally ARM-based computer was achieved in 1987 with the release of the Acorn Archimedes. In 1992, Acorn once more won the Queens Award for Technology for the ARM, the ARM2 featured a 32-bit data bus, 26-bit address space and 27 32-bit registers
13.
PA-RISC
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PA-RISC is an instruction set architecture developed by Hewlett-Packard. As the name implies, it is an instruction set computer architecture. The design is referred to as HP/PA for Hewlett Packard Precision Architecture. The architecture was introduced on 26 February 1986, when the HP3000 Series 930 and HP9000 Model 840 computers were launched featuring the first implementation, PA-RISC has been succeeded by the Itanium ISA, jointly developed by HP and Intel. HP stopped selling PA-RISC-based HP9000 systems at the end of 2008, in the late 1980s, HP was building four series of computers, all based on CISC CPUs. One line was the IBM PC compatible Intel i286-based Vectra Series, HP planned to use PA-RISC to move all of their non-PC compatible machines to a single RISC CPU family. Precision Architecture was introduced in 1986 and it had thirty-two 32-bit integer registers and sixteen 64-bit floating-point registers. The number of floating-point registers was doubled in the 1.1 version to 32 once it became apparent that 16 were inadequate, the architects included Allen Baum, Hans Jeans, Michael J. Mahon, Ruby Bei-Loh Lee, Russel Kao, Steve Muchnick, Terrence C. Miller, David Fotland, and William S. Worley, the first implementation was the TS1, a central processing unit built from discrete transistor-transistor logic devices. Later implementations were multi-chip VLSI designs fabricated in NMOS processes and CMOS. They were first used in a new series of HP3000 machines in the late 1980s – the 930 and 950, commonly known at the time as Spectrum systems, the HP9000 machines were soon upgraded with the PA-RISC processor as well, running the HP-UX version of UNIX. Other operating systems ported to the PA-RISC architecture include Linux, OpenBSD, NetBSD, an interesting aspect of the PA-RISC line is that most of its generations have no Level 2 cache. Instead large Level 1 caches are used, formerly as separate chips connected by a bus, only the PA-7100LC and PA-7300LC had L2 caches. Another innovation of the PA-RISC was the addition of vectorized instructions in the form of MAX, Precision RISC Organization, an industry group led by HP, was founded in 1992, to promote the PA-RISC architecture. Members included Hitachi, Redbrick Software, Allegro Consultants, Mitsubishi, NEC, OKI, the ISA was extended in 1996 to 64 bits, with this revision named PA-RISC2.0. The first PA-RISC2.0 implementation was the PA-8000, which was introduced in January 1996. net Comprehensive PA-RISC chip and computer information chipdb. org Images of different PA-RISC processors
14.
Motorola 68000 series
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The Motorola 68000 series is a family of 32-bit complex instruction set computer microprocessors. During the 1980s and early 1990s, they were popular in personal computers and they were most well known as the processors powering the early Apple Macintosh, the Commodore Amiga, the Sinclair QL, the Atari ST, the WeatherStar, the Sega Genesis, and several others. However, they became most well known as the processors powering desktop computers such as the Apple Macintosh, the Commodore Amiga, the Sinclair QL, the Atari ST, and several others. The 68000 was also the processor of choice in the 1980s for Unix workstations and servers from firms such as Sun Microsystems, NeXT and Silicon Graphics. There was a 68000 version of CP/M called CP/M-68K, which was proposed to be the Atari ST operating system. Also, and perhaps most significantly, the first several versions of Adobes PostScript interpreters were 68000-based, the 68000 in the Apple LaserWriter and LaserWriter Plus was clocked faster than the version used then in Macintosh computers. Thereafter, Adobe generally preferred a RISC for its processor, as its competitors, with their PostScript clones, had gone with RISCs. The early 68000-based Adobe PostScript interpreters and their hardware were named for cold war U. S. rockets and missiles, Atlas, Redstone, today, these systems are either end-of-line, or are using different processors. Since these platforms had their peak in the 1980s, their original manufacturers are unlikely to support an operating system for this hardware or are even out of business. However, the GNU/Linux, NetBSD and OpenBSD operating systems include support for 68000 processors. The 68000 processors were used in the Sega Genesis and SNK Neo Geo consoles as the main CPU. Many arcade boards also used 68000 processors including boards from Capcom, SNK, microcontrollers derived from the 68000 family have been used in a huge variety of applications. For example, CPU32 and ColdFire microcontrollers have been manufactured in the millions as automotive engine controllers, people who are familiar with the PDP-11 or VAX usually feel comfortable with the 68000. With the exception of the split of general purpose registers into specialized data and address registers and it had a more orthogonal instruction set than those of many processors that came before and after. That is, it was possible to combine operations freely with operands. This property made programming relatively easy for humans, and also made it easier to write code generators for compilers, there was no 68050, though at one point it was a project within Motorola. Many of these optimizations were included with the 68060 and were part of its design goals. There is also no revision of the 68060, as Motorola was in the process of shifting away from the 68000 and 88k processor lines into its new PowerPC business, had it been, it would have been a revised 68060, likely with a superior FPU
15.
MIPS architecture
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MIPS is a reduced instruction set computer instruction set architecture developed by MIPS Technologies. The early MIPS architectures were 32-bit, with 64-bit versions added later, multiple revisions of the MIPS instruction set exist, including MIPS I, MIPS II, MIPS III, MIPS IV, MIPS V, MIPS32, and MIPS64. The current revisions are MIPS32 and MIPS64, MIPS32 and MIPS64 define a control register set as well as the instruction set. Computer architecture courses in universities and technical schools often study the MIPS architecture, the architecture greatly influenced later RISC architectures such as Alpha. It used to be popular in supercomputers but all systems have dropped off the TOP500 list. Until late 2006, they were used in many of SGIs computer products. MIPS implementations were also used by Digital Equipment Corporation, NEC, Pyramid Technology, Siemens Nixdorf, in the mid to late 1990s, it was estimated that one in three RISC microprocessors produced was a MIPS implementation. Windows NT supported MIPS until the release of Windows NT4.0 SP3 in 1997, MIPS is a modular architecture supporting up to four coprocessors. In MIPS terminology, COP0 is the System Control Coprocessor, COP1 is an optional FPU, for example, in the original Playstation game console, COP0 is the System Control Coprocessor and COP2 is Geometry Transformation Engine. In the Playstation 2 game console, COP0 is a Toshiba R5900 chip, COP1 is a FPU, MIPS is a load-store architecture, meaning it only performs arithmetic and logic operations between CPU registers, requiring load/store instructions to access memory. Processors based upon the MIPS instruction set have been in production since 1988, over time several enhancements of the instruction set were made. The different revisions which have introduced are MIPS I, MIPS II, MIPS III, MIPS IV. Each revision is a superset of its predecessors, when MIPS Technologies was spun out of Silicon Graphics again in 1998, they refocused on the embedded market. At that time, this property was found to be a problem, and the architecture definition was changed to define a 32-bit MIPS32. Introduced in 1985 with the R2000, introduced in 1990 with the R6000. Introduced in 1992 in the R4000 and it adds 64-bit registers and integer instructions and a floating point square root instruction. MIPS IV is the version of the architecture. It is a superset of MIPS III and is compatible with all existing versions of MIPS, the first implementation of MIPS IV was the R8000, which was introduced in 1994
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PowerPC
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PowerPC is a RISC instruction set architecture created by the 1991 Apple–IBM–Motorola alliance, known as AIM. PowerPC was the cornerstone of AIMs PReP and Common Hardware Reference Platform initiatives in the 1990s and it has since become niche in personal computers, but remain popular as embedded and high-performance processors. Its use in game consoles and embedded applications provided an array of uses. In addition, PowerPC CPUs are still used in AmigaOne and third party AmigaOS4 personal computers, the history of RISC began with IBMs 801 research project, on which John Cocke was the lead developer, where he developed the concepts of RISC in 1975–78. 801-based microprocessors were used in a number of IBM embedded products, the RT was a rapid design implementing the RISC architecture. The result was the POWER instruction set architecture, introduced with the RISC System/6000 in early 1990, the original POWER microprocessor, one of the first superscalar RISC implementations, was a high performance, multi-chip design. IBM soon realized that a microprocessor was needed in order to scale its RS/6000 line from lower-end to high-end machines. Work on a one-chip POWER microprocessor, designated the RSC began, in early 1991, IBM realized its design could potentially become a high-volume microprocessor used across the industry. IBM approached Apple with the goal of collaborating on the development of a family of single-chip microprocessors based on the POWER architecture and this three-way collaboration became known as AIM alliance, for Apple, IBM, Motorola. In 1991, the PowerPC was just one facet of an alliance among these three companies. The PowerPC chip was one of joint ventures involving the three, in their efforts to counter the growing Microsoft-Intel dominance of personal computing. For Motorola, POWER looked like an unbelievable deal and it allowed them to sell a widely tested and powerful RISC CPU for little design cash on their own part. It also maintained ties with an important customer, Apple, and seemed to offer the possibility of adding IBM too, at this point Motorola already had its own RISC design in the form of the 88000 which was doing poorly in the market. Motorola was doing well with their 68000 family and the majority of the funding was focused on this, the 88000 effort was somewhat starved for resources. However, the 88000 was already in production, Data General was shipping 88000 machines, the 88000 had also achieved a number of embedded design wins in telecom applications. The result of various requirements was the PowerPC specification. The differences between the earlier POWER instruction set and PowerPC is outlined in Appendix E of the manual for PowerPC ISA v.2.02, when the first PowerPC products reached the market, they were met with enthusiasm. In addition to Apple, both IBM and the Motorola Computer Group offered systems built around the processors, Microsoft released Windows NT3.51 for the architecture, which was used in Motorolas PowerPC servers, and Sun Microsystems offered a version of its Solaris OS
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SuperH
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SuperH is a 32-bit reduced instruction set computing instruction set architecture developed by Hitachi and currently produced by Renesas. It is implemented by microcontrollers and microprocessors for embedded systems, as of 2015, many of the original patents for the SuperH architecture are expiring and the SH2 CPU has been reimplemented as open source hardware under the name J2. The SuperH processor core family was first developed by Hitachi in the early 1990s, Hitachi has developed a complete group of upward compatible instruction set CPU cores. The SH-1 and the SH-2 were used in the Sega Saturn and these cores have 16-bit instructions for better code density than 32-bit instructions, which was a great benefit at the time, due to the high cost of main memory. A few years later the SH-3 core was added to the SH CPU family, new features included another interrupt concept, a management unit. The SH-3 core also got a DSP extension, then called SH-3-DSP, with extended data paths for efficient DSP processing, special accumulators and a dedicated MAC-type DSP engine, this core was unifying the DSP and the RISC processor world. A derivative was also used with the original SH-2 core, between 1994 and 1996,35.1 million SuperH devices were shipped worldwide. For the Dreamcast, Hitachi developed the SH-4 architecture, superscalar instruction execution and a vector floating point unit were the highlights of this architecture. SH-4 based standard chips were introduced around 1998, the SH-3 and SH-4 architectures support both big-endian and little-endian byte ordering. Hitachi and STMicroelectronics started collaborating as early as 1997 on the design of the SH-4, in 2003, Hitachi and Mitsubishi Electric formed a joint-venture called Renesas Technology, with Hitachi controlling 55% of it. In 2004, Renesas Technology bought STMicroelectronicss share of ownership in the SuperH Inc. Renesas Technology later became Renesas Electronics, following their merger with NEC Electronics. The SH-5 design supported two modes of operation, sHcompact mode is equivalent to the user-mode instructions of the SH-4 instruction set. SHmedia mode is different, using 32-bit instructions with sixty-four 64-bit integer registers. In SHmedia mode the destination of a branch is loaded into a branch register separately from the branch instruction. This allows the processor to prefetch instructions for a branch without having to snoop the instruction stream, however, SH-5 differs because its backward compatibility mode is the 16-bit encoding rather than the 32-bit encoding. The evolution of the SuperH architecture still continues, the last of the SH-2 patents expired in 2014. At LinuxCon Japan 2015, j-core developers presented a cleanroom reimplemention of the SH-2 ISA with extensions, subsequently, a design walkthrough was presented at ELC2016. The open source BSD licensed VHDL code for the J2 core has been proven on Xilinx FPGAs and on ASICs manufactured on TSMCs 180 nm process, additional instructions are easy to add
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SPARC
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The Scalable Processor Architecture is a reduced instruction set computing instruction set architecture originally developed by Sun Microsystems. Since the establishment of SPARC International, Inc. in 1989, SPARC International is also responsible for licensing and promoting the SPARC architecture, managing SPARC trademarks, and providing conformance testing. As a result of SPARC International, SPARC is fully open, non-proprietary, later, SPARC processors were used in SMP and CC-NUMA servers produced by Sun, Solbourne and Fujitsu, among others, and designed for 64-bit operation. As of July 2016, the latest commercial high-end SPARC processors are Fujitsus SPARC64 X+ and SPARC64 XIfx, the SPARC architecture was heavily influenced by the earlier RISC designs including the RISC I and II from the University of California, Berkeley and the IBM801. These original RISC designs were minimalist, including as few features or op-codes as possible and this made them similar to the MIPS architecture in many ways, including the lack of instructions such as multiply or divide. Another feature of SPARC influenced by this early RISC movement is the delay slot. The SPARC processor usually contains as many as 160 general purpose registers, according to the Oracle SPARC Architecture 2015 specification an implementation may contain from 72 to 640 general-purpose 64-bit registers. At any point, only 32 of them are visible to software –8 are a set of global registers. These 24 registers form what is called a window, and at function call/return. Each window has 8 local registers and shares 8 registers with each of the adjacent windows, the shared registers are used for passing function parameters and returning values, and the local registers are used for retaining local values across function calls. Other architectures that include similar register file features include Intel i960, IA-64, the architecture has gone through several revisions. It gained hardware multiply and divide functionality in Version 8, 64-bit were added to the version 9 SPARC specification published in 1994. In SPARC Version 8, the floating point register file has 16 double precision registers, each of them can be used as two single precision registers, providing a total of 32 single precision registers. An odd-even number pair of double precision registers can be used as a quad precision register, SPARC Version 9 added 16 more double precision registers, but these additional registers can not be accessed as single precision registers. No SPARC CPU implements quad-precision operations in hardware as of 2004, tagged add and subtract instructions perform adds and subtracts on values checking that the bottom two bits of both operands are 0 and reporting overflow if they are not. This can be useful in the implementation of the run time for ML, Lisp, the endianness of the 32-bit SPARC V8 architecture is purely big-endian. The latter is used for accessing data from inherently little-endian devices. There have been three revisions of the architecture
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RISC-V
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RISC-V is an open instruction set architecture based on established reduced instruction set computing principles. In contrast to most ISAs, the RISC-V ISA can be used for any purpose, permitting anyone to design, manufacture and sell RISC-V chips. Such uses demand that the designers consider both performance and power efficiency, the instruction set also has a substantial body of supporting software, which fixes a usual weakness of new instruction sets. The RISC-V ISA has been designed with small, fast, and low-power real-world implementations in mind, as of January 2017, version 2.1 of the userspace ISA is fixed and the privileged ISA is available as draft version 1.9.1. The RISC-V authors aim to provide several CPU designs freely available under a BSD license, such licenses allow derivative works, such as RISC-V chip designs, to be either open and free, like RISC-V itself, or closed and proprietary. By contrast, commercial vendors such as ARM Holdings and MIPS Technologies charge substantial license fees for the use of their patents. They also require non-disclosure agreements before releasing documents that describe their designs advantages, many design advances are completely proprietary, never described even to customers. The secrecy interferes with legitimate public educational use, security auditing, and the development of public, low–cost free and open-source software compilers, developing a CPU requires design expertise in several specialties, electronic logic, compilers, and operating systems. Its rare to find this outside of an engineering team. The result is that modern, high-quality general-purpose computer instruction sets have not recently been widely available anywhere, or even explained, because of this, many RISC-V contributors see it as a unified community effort. This need for a base of contributors is part of the reason why RISC-V was engineered to fit so many uses. The RISC-V authors also have research and user-experience validating their designs in silicon and simulation. The RISC-V ISA is a development from a series of academic computer-design projects. It was originated in part to aid such projects, the term RISC dates from about 1980. Before this, there was some knowledge that simpler computers could be effective, simple, effective computers have always been of academic interest. Academics created the RISC instruction set DLX for the first edition of Computer Architecture, david Patterson was an author, and later assisted RISC-V. However DLX was for educational use, academics and hobbyists implemented it using field-programmable gate arrays, but it was not a commercial success. ARM CPUs, version 2 and earlier, had an instruction set, and it is still supported by the GCC
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VAX
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VAX is a discontinued instruction set architecture developed by Digital Equipment Corporation in the mid-1970s. The VAX-11/780, introduced on October 25,1977, was the first of a range of popular, a 32-bit system with a CISC architecture based on DECs earlier PDP-11, VAX was designed to extend or replace DECs various PDP ISAs. The VAX architectures primary features were virtual addressing and its instruction set. Later versions offloaded the compatibility mode and some of the less used CISC instructions to emulation in the system software. The VAX instruction set was designed to be powerful and orthogonal, when it was introduced, many programs were written in assembly language, so having a programmer-friendly instruction set was important. In time, as programs were written in higher-level language, the instruction set became less visible. One unusual aspect of the VAX instruction set is the presence of register masks at the start of each subprogram and these are arbitrary bit patterns that specify, when control is passed to the subprogram, which registers are to be preserved. Since register masks are a form of data embedded within the executable code and this can complicate optimization techniques that are applied on machine code. The native VAX operating system is Digitals VAX/VMS, the VAX architecture and OpenVMS operating system were engineered concurrently to take maximum advantage of each other, as was the initial implementation of the VAXcluster facility. Other VAX operating systems have included various releases of BSD UNIX up to 4. 3BSD, Ultrix-32, VAXELN, more recently, NetBSD and OpenBSD support various VAX models and some work has been done on porting Linux to the VAX architecture. The first VAX model sold was the VAX-11/780, which was introduced on October 25,1977 at the Digital Equipment Corporations Annual Meeting of Shareholders, bill Strecker, C. Gordon Bells doctoral student at Carnegie Mellon University, was responsible for the architecture. Many different models with different prices, performance levels, and capacities were subsequently created, VAX superminicomputers were very popular in the early 1980s. For a while the VAX-11/780 was used as a standard in CPU benchmarks, the actual number of instructions executed in 1 second was about 500,000, which led to complaints of marketing exaggeration. The result was the definition of a VAX MIPS, the speed of a VAX-11/780, within the Digital community the term VUP was the more common term, because MIPS do not compare well across different architectures. The related term cluster VUPs was informally used to describe the performance of a VAXcluster. The VAX-11/780 included a subordinate stand-alone LSI-11 computer that performed microcode load, booting and this was dropped from subsequent VAX models. Enterprising VAX-11/780 users could therefore run three different Digital Equipment Corporation operating systems, VMS on the VAX processor, and either RSX-11M or RT-11 on the LSI-11, the VAX went through many different implementations. The original VAX 11/780 was implemented in TTL and filled a cabinet with a single CPU
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X86
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X86 is a family of backward-compatible instruction set architectures based on the Intel 8086 CPU and its Intel 8088 variant. The term x86 came into being because the names of several successors to Intels 8086 processor end in 86, many additions and extensions have been added to the x86 instruction set over the years, almost consistently with full backward compatibility. The architecture has been implemented in processors from Intel, Cyrix, AMD, VIA and many companies, there are also open implementations. In the 1980s and early 1990s, when the 8088 and 80286 were still in common use, today, however, x86 usually implies a binary compatibility also with the 32-bit instruction set of the 80386. An 8086 system, including such as 8087 and 8089. There were also terms iRMX, iSBC, and iSBX – all together under the heading Microsystem 80, however, this naming scheme was quite temporary, lasting for a few years during the early 1980s. Today, x86 is ubiquitous in both stationary and portable computers, and is also used in midrange computers, workstations, servers. A large amount of software, including operating systems such as DOS, Windows, Linux, BSD, Solaris and macOS, functions with x86-based hardware. There have been attempts, including by Intel itself, to end the market dominance of the inelegant x86 architecture designed directly from the first simple 8-bit microprocessors. Examples of this are the iAPX432, the Intel 960, Intel 860, however, the continuous refinement of x86 microarchitectures, circuitry and semiconductor manufacturing would make it hard to replace x86 in many segments. The table below lists processor models and model series implementing variations of the x86 instruction set, each line item is characterized by significantly improved or commercially successful processor microarchitecture designs. Such x86 implementations are seldom simple copies but often employ different internal microarchitectures as well as different solutions at the electronic, quite naturally, early compatible microprocessors were 16-bit, while 32-bit designs were developed much later. For the personal computer market, real quantities started to appear around 1990 with i386 and i486 compatible processors, other companies, which designed or manufactured x86 or x87 processors, include ITT Corporation, National Semiconductor, ULSI System Technology, and Weitek. Some early versions of these microprocessors had heat dissipation problems, AMD later managed to establish itself as a serious contender with the K6 set of processors, which gave way to the very successful Athlon and Opteron. There were also other contenders, such as Centaur Technology, Rise Technology, VIA Technologies energy efficient C3 and C7 processors, which were designed by the Centaur company, have been sold for many years. Centaurs newest design, the VIA Nano, is their first processor with superscalar and it was, perhaps interestingly, introduced at about the same time as Intels first in-order processor since the P5 Pentium, the Intel Atom. The instruction set architecture has twice been extended to a word size. In 1999-2003, AMD extended this 32-bit architecture to 64 bits and referred to it as x86-64 in early documents, Intel soon adopted AMDs architectural extensions under the name IA-32e, later using the name EM64T and finally using Intel 64
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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
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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
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Rump kernel
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The rump kernels can also run without POSIX directly on top of the Xen hypervisor, the L4 microkernel in Genode OS or even on OS-less bare metal. With drivers, a concept is considered where not only device drivers are included but also file systems. The File System Access Utilities is a subproject built with the rump libraries and it aims to have a set of utilities to access and modify a file system image without having to mount it. The fs-utils does not require superuser account to access to the image or device, the advantage of fs-utils over similar projects such as mtools is supporting the usage of familiar with filesystem Unix commands for a large number of file systems which are supported by NetBSD. Filesystem in Userspace Unikernel Rump kernel home page Kantee, Antti, the Design and Implementation of the Anykernel and Rump Kernels
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User interface
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The user interface, in the industrial design field of human–computer interaction, is the space where interactions between humans and machines occur. Examples of this concept of user interfaces include the interactive aspects of computer operating systems, hand tools, heavy machinery operator controls. The design considerations applicable when creating user interfaces are related to or involve such disciplines as ergonomics and psychology. Generally, the goal of user interface design is to produce a user interface makes it easy, efficient. This generally means that the needs to provide minimal input to achieve the desired output. Other terms for user interface are man–machine interface and when the machine in question is a computer human–computer interface, the user interface or human–machine interface is the part of the machine that handles the human–machine interaction. Membrane switches, rubber keypads and touchscreens are examples of the part of the Human Machine Interface which we can see. In complex systems, the interface is typically computerized. The term human–computer interface refers to this kind of system, in the context of computing the term typically extends as well to the software dedicated to control the physical elements used for human-computer interaction. The engineering of the interfaces is enhanced by considering ergonomics. The corresponding disciplines are human factors engineering and usability engineering, which is part of systems engineering, tools used for incorporating human factors in the interface design are developed based on knowledge of computer science, such as computer graphics, operating systems, programming languages. Nowadays, we use the graphical user interface for human–machine interface on computers. There is a difference between a user interface and an interface or a human–machine interface. A human-machine interface is typically local to one machine or piece of equipment, an operator interface is the interface method by which multiple equipment that are linked by a host control system is accessed or controlled. The system may expose several user interfaces to serve different kinds of users, for example, a computerized library database might provide two user interfaces, one for library patrons and the other for library personnel. The user interface of a system, a vehicle or an industrial installation is sometimes referred to as the human–machine interface. HMI is a modification of the original term MMI, in practice, the abbreviation MMI is still frequently used although some may claim that MMI stands for something different now. Another abbreviation is HCI, but is commonly used for human–computer interaction
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Command-line interface
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A program which handles the interface is called a command language interpreter or shell. The interface is implemented with a command line shell, which is a program that accepts commands as text input. Command-line interfaces to computer operating systems are widely used by casual computer users. Alternatives to the line include, but are not limited to text user interface menus, keyboard shortcuts. Examples of this include the Windows versions 1,2,3,3.1, and 3.11, DosShell, and Mouse Systems PowerPanel. Command-line interfaces are preferred by more advanced computer users, as they often provide a more concise. Programs with command-line interfaces are generally easier to automate via scripting, a program that implements such a text interface is often called a command-line interpreter, command processor or shell. Under most operating systems, it is possible to replace the shell program with alternatives, examples include 4DOS for DOS, 4OS2 for OS/2. For example, the default Windows GUI is a program named EXPLORER. EXE. These programs are shells, but not CLIs, application programs may also have command line interfaces. When a program is launched from an OS command line shell, interactive command line sessions, After launch, a program may provide an operator with an independent means to enter commands in the form of text. OS inter-process communication, Most operating systems support means of inter-process communication, Command lines from client processes may be redirected to a CLI program by one of these methods. Some applications support only a CLI, presenting a CLI prompt to the user, Some examples of CLI-only applications are, DEBUG Diskpart Ed Edlin Fdisk Ping Some computer programs support both a CLI and a GUI. In some cases, a GUI is simply a wrapper around a separate CLI executable file, in other cases, a program may provide a CLI as an optional alternative to its GUI. CLIs and GUIs often support different functionality, for example, all features of MATLAB, a numerical analysis computer program, are available via the CLI, whereas the MATLAB GUI exposes only a subset of features. The early Sierra games, like the first three Kings Quest games, used commands from a command line to move the character around in the graphic window. Early computer systems often used teleprinter machines as the means of interaction with a human operator, the computer became one end of the human-to-human teleprinter model. So instead of a human communicating with another human over a teleprinter, in time, the actual mechanical teleprinter was replaced by a glass tty, and then by a smart terminal
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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
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Free and open-source software
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Free and open-source software is computer software that can be classified as both free software and open-source software. This is in contrast to proprietary software, where the software is under restrictive copyright, the benefits of using FOSS can include decreasing software costs, increasing security and stability, protecting privacy, and giving users more control over their own hardware. Free, open-source operating systems such as Linux and descendents of BSD are widely utilized today, powering millions of servers, desktops, smartphones, Free software licenses and open-source licenses are used by many software packages. In the 1950s, 1960s, and 1970s to 1980s, it was common for users to have the source code for all programs they used. Software, including source code, was shared by individuals who used computers. Most companies had a model based on hardware sales, and provided or bundled software with hardware. Organizations of users and suppliers were formed to facilitate the exchange of software, see, for example, SHARE, by the late 1960s, the prevailing business model around software was changing. In United States vs. IBM, filed 17 January 1969, while some software might always be free, there would be a growing amount of software that was for sale only. Software development for the GNU operating system began in January 1984, an article outlining the project and its goals was published in March 1985 titled the GNU Manifesto. The manifesto included significant explanation of the GNU philosophy, Free Software Definition, the Linux kernel, started by Linus Torvalds, was released as freely modifiable source code in 1991. Initially, Linux was not released under a free or open-source software license, however, with version 0.12 in February 1992, he relicensed the project under the GNU General Public License. Much like Unix, Torvalds kernel attracted the attention of volunteer programmers, freeBSD and NetBSD were released as free software when the USL v. BSDi lawsuit was settled out of court in 1993. OpenBSD forked from NetBSD in 1995, also in 1995, The Apache HTTP Server, commonly referred to as Apache, was released under the Apache License 1.0. In 1997, Eric Raymond published The Cathedral and the Bazaar and this code is today better known as Mozilla Firefox and Thunderbird. Netscapes act prompted Raymond and others to look into how to bring the FSFs free software ideas, the new name they chose was open source, and quickly Bruce Perens, publisher Tim OReilly, Linus Torvalds, and others signed on to the rebranding. The Open Source Initiative was founded in February 1998 to encourage use of the new term, a Microsoft executive publicly stated in 2001 that open source is an intellectual property destroyer. I cant imagine something that could be worse than this for the software business and this view perfectly summarizes the initial response to FOSS by some software corporations. IBM, Oracle, Google and State Farm are just a few of the companies with a serious public stake in todays competitive open-source market, there has been a significant shift in the corporate philosophy concerning the development of free and open-source software
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Operating system
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An operating system is system software that manages computer hardware and software resources and provides common services for computer programs. All computer programs, excluding firmware, require a system to function. Operating systems are found on many devices that contain a computer – from cellular phones, the dominant desktop operating system is Microsoft Windows with a market share of around 83. 3%. MacOS by Apple Inc. is in place, and the varieties of Linux is in third position. Linux distributions are dominant in the server and supercomputing sectors, other specialized classes of operating systems, such as embedded and real-time systems, exist for many applications. A single-tasking system can run one program at a time. Multi-tasking may be characterized in preemptive and co-operative types, in preemptive multitasking, the operating system slices the CPU time and dedicates a slot to each of the programs. Unix-like operating systems, e. g. Solaris, Linux, cooperative multitasking is achieved by relying on each process to provide time to the other processes in a defined manner. 16-bit versions of Microsoft Windows used cooperative multi-tasking, 32-bit versions of both Windows NT and Win9x, used preemptive multi-tasking. Single-user operating systems have no facilities to distinguish users, but may allow multiple programs to run in tandem, a distributed operating system manages a group of distinct computers and makes them appear to be a single computer. The development of networked computers that could be linked and communicate with each other gave rise to distributed computing, distributed computations are carried out on more than one machine. When computers in a work in cooperation, they form a distributed system. The technique is used both in virtualization and cloud computing management, and is common in large server warehouses, embedded operating systems are designed to be used in embedded computer systems. They are designed to operate on small machines like PDAs with less autonomy and they are able to operate with a limited number of resources. They are very compact and extremely efficient by design, Windows CE and Minix 3 are some examples of embedded operating systems. A real-time operating system is a system that guarantees to process events or data by a specific moment in time. A real-time operating system may be single- or multi-tasking, but when multitasking, early computers were built to perform a series of single tasks, like a calculator. Basic operating system features were developed in the 1950s, such as resident monitor functions that could run different programs in succession to speed up processing
30.
Research Unix
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The term Research Unix first appeared in the Bell System Technical Journal to distinguish it from other versions internal to Bell Labs whose code-base had diverged from the primary CSRC version. However, that term was little-used until Version 8 Unix, but has been applied to earlier versions as well. Prior to V8, the system was most commonly called simply UNIX or the UNIX Time-Sharing System. AT&T licensed Version 5 to educational institutions, and Version 6 also to commercial sites, schools paid $200 and others $20,000, discouraging most commercial use, but Version 6 was the most widely used version into the 1980s. So, the first Research Unix would be the First Edition, another common way of referring to them is Version x Unix, where x is the manual edition. All modern editions of Unix—excepting Unix-like implementations such as Coherent, Minix, starting with the 8th Edition, versions of Research Unix had a close relationship to BSD. This began by using 4. 1cBSD as the basis for the 8th Edition. 1c and this continued with 9th and 10th. The ordinary user command-set was, I guess, a bit more BSD-flavored than SysVish, Version 3, Version 4 and Version 5 should not be confused with the UNIX3.0, UNIX4.0 and UNIX5.0 releases by the AT&T UNIX Support Group. After Version 10, Unix development at Bell Labs was stopped in favor of a system, Plan 9 from Bell Labs. In 2002, Caldera International released V7 Unix as FOSS under a permissive BSD-like software license, in 2017, Unix Heritage Society and Alcatel-Lucent USA Inc. List of new features in Research Unix 9th Edition
31.
University of California, Berkeley
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The University of California, Berkeley, is a public research university located in Berkeley, California. In 1960s, UC Berkeley was particularly noted for the Free Speech Movement as well as the Anti-Vietnam War Movement led by its students. S, Department of Energy, and is home to many world-renowned research institutes and organizations including Mathematical Sciences Research Institute and Space Sciences Laboratory. Faculty member J. R. Oppenheimer, the father of the atomic bomb, Lawrence Livermore Lab also discovered or co-discovered six chemical elements. The Academic Ranking of World Universities also ranks the University of California, Berkeley, third in the world overall, in 1866, the private College of California purchased the land comprising the current Berkeley campus. Ten faculty members and almost 40 students made up the new University of California when it opened in Oakland in 1869, billings was a trustee of the College of California and suggested that the college be named in honor of the Anglo-Irish philosopher George Berkeley. In 1870, Henry Durant, the founder of the College of California, with the completion of North and South Halls in 1873, the university relocated to its Berkeley location with 167 male and 22 female students and held its first classes. In 1905, the University Farm was established near Sacramento, ultimately becoming the University of California, by the 1920s, the number of campus buildings had grown substantially, and included twenty structures designed by architect John Galen Howard. Robert Gordon Sproul served as president from 1930 to 1958, by 1942, the American Council on Education ranked UC Berkeley second only to Harvard University in the number of distinguished departments. During World War II, following Glenn Seaborgs then-secret discovery of plutonium, UC Berkeley physics professor J. Robert Oppenheimer was named scientific head of the Manhattan Project in 1942. Along with the Lawrence Berkeley National Laboratory, Berkeley is now a partner in managing two other labs, Los Alamos National Laboratory and Lawrence Livermore National Laboratory, originally, military training was compulsory for male undergraduates, and Berkeley housed an armory for that purpose. In 1917, Berkeleys ROTC program was established, and its School of Military Aeronautics trained future pilots, including Jimmy Doolittle, both Robert McNamara and Frederick C. Weyand graduated from UC Berkeleys ROTC program, earning B. A. degrees in 1937 and 1938, in 1926, future fleet admiral Chester W. Nimitz established the first Naval Reserve Officers Training Corps unit at Berkeley. The Board of Regents ended compulsory military training at Berkeley in 1962, during the McCarthy era in 1949, the Board of Regents adopted an anti-communist loyalty oath. A number of faculty members objected and were dismissed, ten years passed before they were reinstated with back pay, in 1952, the University of California became an entity separate from the Berkeley campus. Each campus was given autonomy and its own Chancellor. Then-president Sproul assumed presidency of the entire University of California system, Berkeley gained a reputation for student activism in the 1960s with the Free Speech Movement of 1964 and opposition to the Vietnam War. In the highly publicized Peoples Park protest in 1969, students and the school conflicted over use of a plot of land, then governor of California Ronald Reagan called the Berkeley campus a haven for communist sympathizers, protesters, and sex deviants. Modern students at Berkeley are less active, with a greater percentage of moderates and conservatives
32.
Fork (software development)
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The term often implies not merely a development branch, but also a split in the developer community, a form of schism. Free and open-source software is that which, by definition, may be forked from the development team without prior permission without violating copyright law. However, licensed forks of proprietary software also happen, the word fork stems from the Latin word furca, meaning a fork or similarly shaped instrument. Fork in the meaning of to divide in branches, go separate ways has been used as early as the 14th century. In the software environment, the word evokes the fork system call, however, fork was in use in the present sense by 1995 to describe the XEmacs split, and was an understood usage in the GNU Project by 1996. Thus, there is a penalty associated with forking. The relationship between the different teams can be cordial or very bitter and he notes in the Jargon File, David A. Wheeler notes four possible outcomes of a fork, with examples, The death of the fork. This is by far the most common case and it is easy to declare a fork, but considerable effort to continue independent development and support. With a DVCS such as Mercurial or Git, the way to contribute to a project is to first branch the repository. Forks often restart version numbering from 0.1 or 1.0 even if the software was at version 3.0,4.0. An exception is when the software is designed to be a drop-in replacement for the original project. In proprietary software, the copyright is held by the employing entity. This is almost always an economic decision to generate a greater market share, a notable proprietary fork not of this kind is the many varieties of proprietary Unix—almost all derived from AT&T Unix under license and all called Unix, but increasingly mutually incompatible. The BSD licenses permit forks to become proprietary software, and some say that commercial incentives thus make proprietisation almost inevitable, examples include macOS, Cedega and CrossOver, EnterpriseDB, Supported PostgreSQL with their proprietary ESM storage system, and Netezzas proprietary highly scalable derivative of PostgreSQL. Some of these vendors contribute back changes to the community project, while some keep their changes as their own competitive advantages
33.
386BSD
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386BSD, sometimes called Jolix, is a discontinued free Unix-like operating system based on BSD, first released in 1992. It ran on PC-compatible computer systems based on the 32-bit Intel 80386 microprocessor, 386BSD innovations include role-based security, ring buffers, self-ordered configuration and modular kernel design. The BSDs for PC descend from it, 386BSD was written mainly by Berkeley alumni Lynne Jolitz and William Jolitz. Work on porting 4. 3BSD-Reno and later 4. 3BSD Net/2 to the Intel 80386 was done for the University of California by William Jolitz at Berkeley,4. 3BSD Net/2 was an incomplete non-operational release, with portions withheld by the University of California as encumbered. The port began in 1989 and the first, incomplete traces of the port can be found in 4. 3BSD Net/2 of 1991 and it was first released in March 1992 and in a much more usable version on July 14,1992. The porting process with code was extensively documented in an 18-part series written by Lynne Jolitz, after the release of 386BSD0.1, a group of users began collecting bug fixes and enhancements, releasing them as an unofficial patchkit. Around the same time, the NetBSD project was founded by a different group of 386BSD users, both projects continue to this day. There has never been any legal filings or claims from the University, USL, finally, no code developed for 386BSD done by William Jolitz and Lynne Jolitz was at issue in any of these lawsuits. In late 1994, a finished version 386BSD Release 1.0 was distributed by Dr. Dobbs Journal on CDROM only due to the size of the release and was a best-selling CDROM for three years. On August 5,2016 an update was pushed to the 386BSD github by developer Ben Jolitz, however, as of March 16,2017, almost all of the documentation remains the same as version 1.0, and a change log was not available. 386BSD is often confused with BSD/386 which was a different project developed by BSDi, BSD/386 used the same 386BSD code contributed to the University of California on 4. 3BSD NET/2. Although Jolitz worked briefly for UUNET in 1991, the work he did for them diverged from that contributed to the University of California, all rights with respect to 386BSD and JOLIX are now held exclusively by William Jolitz and Lynne Jolitz. 386BSD public releases ended in 1997 since code is now available from the many 386BSD-derived operating systems today, portions of 386BSD may be found in other open systems such as OpenSolaris. Remarks on the history of 386BSD by Lynne Jolitz Remarks on the history of 386BSD by Greg Lehey More information on the releases of 386BSD Browsable 386BSD kernel sources
34.
Embedded system
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An embedded system is a computer system with a dedicated function within a larger mechanical or electrical system, often with real-time computing constraints. It is embedded as part of a device often including hardware. Embedded systems control many devices in use today. Ninety-eight percent of all microprocessors are manufactured as components of embedded systems, examples of properties of typically embedded computers when compared with general-purpose counterparts are low power consumption, small size, rugged operating ranges, and low per-unit cost. This comes at the price of limited processing resources, which make them more difficult to program. For example, intelligent techniques can be designed to power consumption of embedded systems. Modern embedded systems are based on microcontrollers, but ordinary microprocessors are also common. In either case, the processor used may be ranging from general purpose to those specialised in certain class of computations. A common standard class of dedicated processors is the signal processor. Since the embedded system is dedicated to tasks, design engineers can optimize it to reduce the size and cost of the product and increase the reliability. Some embedded systems are mass-produced, benefiting from economies of scale, complexity varies from low, with a single microcontroller chip, to very high with multiple units, peripherals and networks mounted inside a large chassis or enclosure. One of the very first recognizably modern embedded systems was the Apollo Guidance Computer, an early mass-produced embedded system was the Autonetics D-17 guidance computer for the Minuteman missile, released in 1961. When the Minuteman II went into production in 1966, the D-17 was replaced with a new computer that was the first high-volume use of integrated circuits. Since these early applications in the 1960s, embedded systems have come down in price and there has been a rise in processing power. An early microprocessor for example, the Intel 4004, was designed for calculators and other systems but still required external memory. By the early 1980s, memory, input and output system components had been integrated into the chip as the processor forming a microcontroller. Microcontrollers find applications where a computer would be too costly. A comparatively low-cost microcontroller may be programmed to fulfill the role as a large number of separate components
35.
Computer architecture
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In computer engineering, computer architecture is a set of rules and methods that describe the functionality, organization, and implementation of computer systems. Some definitions of architecture define it as describing the capabilities and programming model of a computer, in other definitions computer architecture involves instruction set architecture design, microarchitecture design, logic design, and implementation. The first documented computer architecture was in the correspondence between Charles Babbage and Ada Lovelace, describing the analytical engine, johnson had the opportunity to write a proprietary research communication about the Stretch, an IBM-developed supercomputer for Los Alamos National Laboratory. Brooks went on to develop the IBM System/360 line of computers. Later, computer users came to use the term in many less-explicit ways, the earliest computer architectures were designed on paper and then directly built into the final hardware form. The discipline of architecture has three main subcategories, Instruction Set Architecture, or ISA. The ISA defines the code that a processor reads and acts upon as well as the word size, memory address modes, processor registers. Microarchitecture, or computer organization describes how a processor will implement the ISA. The size of a computers CPU cache for instance, is an issue that generally has nothing to do with the ISA, system Design includes all of the other hardware components within a computing system. These include, Data processing other than the CPU, such as memory access Other issues such as virtualization, multiprocessing. There are other types of computer architecture, E. g. the C, C++, or Java standards define different Programmer Visible Macroarchitecture. UISA —a group of machines with different hardware level microarchitectures may share a common microcode architecture, pin Architecture, The hardware functions that a microprocessor should provide to a hardware platform, e. g. the x86 pins A20M, FERR/IGNNE or FLUSH. Also, messages that the processor should emit so that external caches can be invalidated, pin architecture functions are more flexible than ISA functions because external hardware can adapt to new encodings, or change from a pin to a message. The term architecture fits, because the functions must be provided for compatible systems, the purpose is to design a computer that maximizes performance while keeping power consumption in check, costs low relative to the amount of expected performance, and is also very reliable. For this, many aspects are to be considered which includes Instruction Set Design, Functional Organization, Logic Design, the implementation involves Integrated Circuit Design, Packaging, Power, and Cooling. Optimization of the design requires familiarity with Compilers, Operating Systems to Logic Design, an instruction set architecture is the interface between the computers software and hardware and also can be viewed as the programmers view of the machine. Computers do not understand high level languages such as Java, C++, a processor only understands instructions encoded in some numerical fashion, usually as binary numbers. Software tools, such as compilers, translate those high level languages into instructions that the processor can understand, besides instructions, the ISA defines items in the computer that are available to a program—e. g
36.
Permissive software licence
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A Permissive software license, sometimes also called BSD-like or BSD-style license, is a FOSS software licence with minimal requirements about how the software can be redistributed. Examples include the MIT Licence, BSD licences and the Apache licence, as of 2016, the most popular FOSS licence is the permissive MIT licence. The Open Source Initiative defines a software license as a non-copyleft license. GitHubs choosealicense website described the MIT permissive license as, lets people do anything they want with your code as long as they provide attribution back to you, california Western School of Laws newmediarights. Copycenter is a term used to explain the modified BSD licence. The term was presented by Kirk McKusick, a computer scientist famous for his work on BSD and it is a word play on copyright, copyleft and copy center. ’ The liberty to make as many copies as you want is in fact also provided by all copyleft licenses. However, unlike both copyleft licenses and copyright law, permissive free software licenses do not control the terms that a derivative work falls under. The Copyfree Initiative defines Copyfree as a type of permissive copyright license which falls under their Copyfree Standard Definition, Copyfree licenses include the Simplified BSD licence, the Open Works license, and others, but excludes the GNU GPL or other copyleft licenses. The Creative Commons CC0 public domain dedication and the WTFPL license are also considered to be copyfree, while all copyfree licenses are permissive licenses, not all permissive licenses are copyfree, because they may introduce limitations not allowed under the copyfree definition. Therefore, copyfree can be seen as subset of permissive free licenses, the Apache Licence 2.0 is an example of a non-copyfree permissive licence. Another notable example is the Creative Commons Attribution 3.0 license, however, permissive licenses are not actually equivalent to releasing a work into the public domain. Permissive licenses often do stipulate some limited requirements, such as that the original authors must be credited, copyleft licenses enforce the publication of the source code under the copyleft license. Also permissive licenses have often an excellent licence compatibility, in comparison to copyleft licenses who cant be always freely combined and mixed, however, most GPLv2 licensed software allows to upgrade to the terms of later versions of the GPL, achieving by that a somewhat better inter-GPL compatibility. Also, some copyleft licenses have exception clauses that allow combining them with software that is under different licenses or license versions, in general permissive licenses show a good licence compatibility with most other software licenses in most situations. Due to their non-restrictiveness most permissive software licenses are compatible with copyleft licenses. Copyleft licenses dont allow the addition of additional restrictive clauses which would be required in a combined work made from copyleft code. Popular modern permissive licenses, as the MIT Licence, the 3-clause BSD licence, some licenses do not allow derived works to add a restriction that says a redistributor cannot add more restrictions. Examples include the CDDL and MsPL, however such restrictions also make the license incompatible with permissive free software licenses
37.
Source code
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In computing, source code is any collection of computer instructions, possibly with comments, written using a human-readable programming language, usually as ordinary text. The source code of a program is designed to facilitate the work of computer programmers. The source code is often transformed by an assembler or compiler into binary machine code understood by the computer, the machine code might then be stored for execution at a later time. Alternatively, source code may be interpreted and thus immediately executed, most application software is distributed in a form that includes only executable files. If the source code were included it would be useful to a user, programmer or a system administrator, the Linux Information Project defines source code as, Source code is the version of software as it is originally written by a human in plain text. The notion of source code may also be more broadly, to include machine code and notations in graphical languages. It is therefore so construed as to include code, very high level languages. Often there are several steps of program translation or minification between the source code typed by a human and an executable program. The earliest programs for stored-program computers were entered in binary through the front panel switches of the computer and this first-generation programming language had no distinction between source code and machine code. When IBM first offered software to work with its machine, the code was provided at no additional charge. At that time, the cost of developing and supporting software was included in the price of the hardware, for decades, IBM distributed source code with its software product licenses, until 1983. Most early computer magazines published source code as type-in programs, Source code can also be stored in a database or elsewhere. The source code for a piece of software may be contained in a single file or many files. Though the practice is uncommon, a source code can be written in different programming languages. For example, a program written primarily in the C programming language, in some languages, such as Java, this can be done at run time. The code base of a programming project is the larger collection of all the source code of all the computer programs which make up the project. It has become practice to maintain code bases in version control systems. Moderately complex software customarily requires the compilation or assembly of several, sometimes dozens or even hundreds, in these cases, instructions for compilations, such as a Makefile, are included with the source code
38.
Theo de Raadt
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Theo de Raadt is a software engineer who lives in Calgary, Alberta, Canada. He is the founder and leader of the OpenBSD and OpenSSH projects, Theo de Raadt is the eldest of four children to a Dutch father and a South African mother, with two sisters and a brother. Concern over the mandatory two-year armed forces conscription in South Africa led the family to emigrate to Calgary, Alberta, in 1983, the largest recession in Canada since the Great Depression sent the family to the Yukon. Prior to the move De Raadt got his first computer, a Commodore VIC-20 and it is with these computers that he first began to develop software. In 1992 he obtained a BSc in Computer Science from the University of Calgary, the new project would centre its focus on clean, portable, correct code with the goal being to produce a unified, multi-platform, production-quality, BSD-based operating system. Because of the importance of such as the Internet in the distributed, collaborative nature of its development, De Raadt suggested the name NetBSD. The first NetBSD source code repository was established on March 21,1993 and this was derived from 386BSD0.1 plus the version 0.2.2 unofficial patchkit, with several programs from the Net/2 release missing from 386BSD re-integrated, and various other improvements. In August 1993, NetBSD0.9 was released, which contained many enhancements and this was still a PC-platform-only release, although by this time work was underway to add support for other architectures. NetBSD1.0 was released in October,1994 and this was the first multi-platform release, supporting the IBM PC compatible, HP9000 Series 300, Amiga, 68k Macintosh, Sun-4c series and PC532. Also in this release, the legally encumbered Net/2-derived source code was replaced with equivalent code from 4. 4BSD-lite, De Raadt played a vital role in the creation of the SPARC port, as together with Chuck Cranor, he implemented much of the initial code. In December 1994, De Raadt was asked to resign his position as a developer and member of the NetBSD core team. The reason for this is not wholly clear, although there are claims that it was due to personality clashes within the NetBSD project, in October 1995, De Raadt founded OpenBSD, a new project forked from NetBSD1.0. The initial release, OpenBSD1.2, was made in July 1996, since then, the project has followed a schedule of a release every six months, each of which is maintained and supported for one year. S. AUUG Conference in Melbourne, Australia and FISL in Porto Alegre, RS, after De Raadt stated his disapproval of the U. S. Funding from the grant had been used in the development of OpenSSH and OpenBSD and this resulted in criticism among some that the US military held an anti-free speech attitude. The grant termination was, however, not as bad a blow as some portrayed it, the projects supporters rallied to help and the hackathon went on almost as planned. The funding was cut mere months before the end of the grant, De Raadt is also well known for his advocacy of free software drivers. He has long been critical of developers of Linux and other platforms for their tolerance of non-free drivers
39.
Internet
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The Internet is the global system of interconnected computer networks that use the Internet protocol suite to link devices worldwide. The origins of the Internet date back to research commissioned by the United States federal government in the 1960s to build robust, the primary precursor network, the ARPANET, initially served as a backbone for interconnection of regional academic and military networks in the 1980s. Although the Internet was widely used by academia since the 1980s, Internet use grew rapidly in the West from the mid-1990s and from the late 1990s in the developing world. In the two decades since then, Internet use has grown 100-times, measured for the period of one year, newspaper, book, and other print publishing are adapting to website technology, or are reshaped into blogging, web feeds and online news aggregators. The entertainment industry was initially the fastest growing segment on the Internet, the Internet has enabled and accelerated new forms of personal interactions through instant messaging, Internet forums, and social networking. Business-to-business and financial services on the Internet affect supply chains across entire industries, the Internet has no centralized governance in either technological implementation or policies for access and usage, each constituent network sets its own policies. The term Internet, when used to refer to the global system of interconnected Internet Protocol networks, is a proper noun. In common use and the media, it is not capitalized. Some guides specify that the word should be capitalized when used as a noun, the Internet is also often referred to as the Net, as a short form of network. Historically, as early as 1849, the word internetted was used uncapitalized as an adjective, the designers of early computer networks used internet both as a noun and as a verb in shorthand form of internetwork or internetworking, meaning interconnecting computer networks. The terms Internet and World Wide Web are often used interchangeably in everyday speech, however, the World Wide Web or the Web is only one of a large number of Internet services. The Web is a collection of interconnected documents and other web resources, linked by hyperlinks, the term Interweb is a portmanteau of Internet and World Wide Web typically used sarcastically to parody a technically unsavvy user. The ARPANET project led to the development of protocols for internetworking, the third site was the Culler-Fried Interactive Mathematics Center at the University of California, Santa Barbara, followed by the University of Utah Graphics Department. In an early sign of growth, fifteen sites were connected to the young ARPANET by the end of 1971. These early years were documented in the 1972 film Computer Networks, early international collaborations on the ARPANET were rare. European developers were concerned with developing the X.25 networks, in December 1974, RFC675, by Vinton Cerf, Yogen Dalal, and Carl Sunshine, used the term internet as a shorthand for internetworking and later RFCs repeated this use. Access to the ARPANET was expanded in 1981 when the National Science Foundation funded the Computer Science Network, in 1982, the Internet Protocol Suite was standardized, which permitted worldwide proliferation of interconnected networks.5 Mbit/s and 45 Mbit/s. Commercial Internet service providers emerged in the late 1980s and early 1990s, the ARPANET was decommissioned in 1990
40.
OpenBSD
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OpenBSD is a free and open source Unix-like computer operating system descended from Berkeley Software Distribution, a Research Unix derivative developed at the University of California, Berkeley. In late 1995, Theo de Raadt forked it from NetBSD, besides the operating system as a whole, the project maintains portable versions of many subsystems, most notably OpenSSH, which are available as packages in other operating systems. The project is known for its developers insistence on open-source code, good documentation, code correctness and it has strict policies on licensing, preferring the ISC license and other variants of the Simplified BSD License. Many of its security features are optional or absent in other operating systems and its developers frequently audit the source tree for software bugs and security holes. De Raadt coordinates the project from his home in Calgary, Alberta and its logo and mascot is a pufferfish named Puffy. In December 1994, NetBSD co-founder Theo de Raadt was asked to resign from his position as a developer and member of the NetBSD core team. The reason for this is not wholly clear, although there are claims that it was due to personality clashes within the NetBSD project, in October 1995, de Raadt founded OpenBSD, a new project forked from NetBSD1.0. The initial release, OpenBSD1.2, was made in July 1996, since then, the project has followed a schedule of a release every six months, each of which is supported for one year. Just how widely OpenBSD is used is hard to determine as its developers do not publish or collect usage statistics. OpenBSDs security enhancements, built-in cryptography, and the pf packet filter suit it for use in the security industry, such as on firewalls, intrusion-detection systems, and VPN gateways. Proprietary systems from several manufacturers are based on OpenBSD, including devices from Armorlogic, Calyptix Security, GeNUA, RTMX, later versions of Microsofts Services for UNIX, an extension to the Windows operating system providing Unix-like functionality, use large amounts of OpenBSD code. OpenBSD ships with the X Window System and is suitable for use on the desktop, packages are available for popular applications, including desktop environments such as GNOME, KDE, and Xfce, and web browsers such as Firefox and Chromium. The project also includes three window managers in the distribution, cwm, FVWM, and twm. OpenBSD used to include a fork of Apache 1.3, in the 5.6 release, Nginx was replaced with httpd, an HTTP server with FastCGI and Transport Layer Security support. As of May 2016, Apache and Nginx are still available as ports, development is continuous, and team management is open and tiered. Snapshot releases are available at frequent intervals. Maintenance patches for supported releases may be applied manually or by updating the system against the branch of the CVS repository for that release. The standard OpenBSD kernel, as maintained by the project, is recommended for end users
41.
Software versioning
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Software versioning is the process of assigning either unique version names or unique version numbers to unique states of computer software. Within a given version number category, these numbers are assigned in increasing order. At a fine-grained level, revision control is used for keeping track of incrementally different versions of electronic information. A variety of version numbering schemes have been created to track of different versions of a piece of software. The ubiquity of computers has led to these schemes being used in contexts outside computing. In sequence-based software versioning schemes, each release is assigned a unique identifier that consists of one or more sequences of numbers or letters. This practice permits users to evaluate how much real-world testing a given software release has undergone. This approach commonly permits the level of numbering, but does not apply this level of rigor to changes in that number,1.3.1,1.3.2,1.3.3,1.3.4. A typical product might use the numbers 0.9,0.9.1,0.9.2,0.9.3,1.0,1.0.1,1.0.2,1.1,1.1.1,2.0,2.0.1,2.0.2,2.1,2.1.1,2.1.2,2.2, etc.1 to 5.5, or Adobe Photoshop 5 to 5.5. This may be done to emphasize the value of the upgrade to the user, or, as in Adobes case. A different approach is to use the major and minor numbers, along with an alphanumeric string denoting the type, e. g. alpha. A software release train using this approach might look like 0.5,0.6,0.7,0.8,0.9 ==1. 0b1,1. 0b2,1. 0b3 ==1. 0rc1 ==1.0. If 1. 0rc1 turns out to have bugs which must be fixed, it turns into 1. 0rc2, if you do, you must roll out another release at that lower level. Other schemes impart meaning on individual sequences, major. minor or major, shared libraries in Solaris and Linux may use the current. revision. age format where current, The most recent interface number that the library implements. Revision, The implementation number of the current interface, age, The difference between the newest and oldest interfaces that the library implements. A similar problem of relative change significance and versioning nomenclature exists in book publishing, in most proprietary software, the first released version of a software product has version 1. Some projects use the version number to indicate incompatible releases. Two examples are Apache APR and the FarCry CMS, Semantic Versioning is a formal convention for specifying compatibility using a three-part version number, major version, minor version, and patch
42.
Minicomputer
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A minicomputer, or colloquially mini, is a class of smaller computers that developed in the mid-1960s and sold for much less than mainframe and mid-size computers from IBM and its direct competitors. The class formed a group with its own software architectures. Minis were designed for control, instrumentation, human interaction, and communication switching as distinct from calculation, many were sold indirectly to Original Equipment Manufacturers for final end use application. During the two decade lifetime of the class, almost 100 companies formed and only a half dozen remained. They usually took up one or a few 19-inch rack cabinets, the definition of minicomputer is vague with the consequence that there are a number of candidates for the first minicomputer. An early and highly successful minicomputer was Digital Equipment Corporations 12-bit PDP-8, later versions of the PDP-8 took advantage of small-scale integrated circuits. The important precursors of the PDP-8 include the PDP-5, LINC, the TX-0, the TX-2, DEC gave rise to a number of minicomputer companies along Massachusetts Route 128, including Data General, Wang Laboratories, Apollo Computer, and Prime Computer. Minicomputers were also known as midrange computers and they grew to have relatively high processing power and capacity. They were used in manufacturing process control, telephone switching and to control laboratory equipment, in the 1970s, they were the hardware that was used to launch the computer-aided design industry and other similar industries where a smaller dedicated system was needed. The 7400 series of TTL integrated circuits started appearing in minicomputers in the late 1960s, the 74181 arithmetic logic unit was commonly used in the CPU data paths. Each 74181 had a bus width of four bits, hence the popularity of bit-slice architecture, some scientific computers, such as the Nicolet 1080, would use the 7400 series in groups of five ICs for their uncommon twenty bits architecture. Starting in the 1980s, many minicomputers used VLSI circuits, the result was that minicomputers and computer terminals were replaced by networked workstations, file servers and PCs in some installations, beginning in the latter half of the 1980s. Also, the Microsoft Windows series of operating systems, beginning with Windows NT, now included server versions that supported preemptive multitasking, Digital Equipment Corporation was once the leading minicomputer manufacturer, at one time the second-largest computer company after IBM. DEC was sold to Compaq in 1998, while Data General was acquired by EMC Corporation, today only a few proprietary minicomputer architectures survive. The IBM System/38 operating system, which introduced many advanced concepts, realising the importance of the myriad lines of legacy code written, AS stands for Application System. Great efforts were made by IBM to enable programs written for the System/34. The AS/400 was replaced by the iSeries, which was replaced by the System i. In 2008, the System i was replaced by the IBM Power Systems, by contrast, competing proprietary computing architectures from the early 1980s, such as DECs VAX, Wang VS and Hewlett Packards HP3000 have long been discontinued without a compatible upgrade path
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Pocket PC
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It has some of the abilities of modern desktop PCs. As of 2010, thousands of applications exist for handhelds adhering to the Microsoft Pocket PC specification, some of these devices are also mobile phones. Microsoft-compliant Pocket PCs can be used with many such as GPS receivers, barcode readers, RFID readers. But in 2010, even Windows Mobile devices were discontinued in favor of Windows Phone devices, the Pocket PC was an evolution from prior calculator-sized computers. Keystroke-programmable calculators which could do business and scientific applications were available by the 1970s. In 1982, Hewlett Packards HP-75 incorporated a 1-line text display, the HP 95LX, HP 100LX and HP 200LX series packed a PC-compatible MS-DOS computer with graphics display and QWERTY keyboard into a palmtop format. The HP OmniGo 100 and 120 used a pen and graphics interface on DOS-based PC/GEOS, the HP 300LX built a palmtop computer on the Windows CE operating system, but not until the form factor and features of the Palm platform were adapted that it was named the Pocket PC. From a technical standpoint, Pocket PC is a Microsoft specification that sets various hardware and software requirements for mobile devices bearing the Pocket PC label. The Pocket PC/Windows Mobile OS was superseded by Windows Phone on February 15,2010 when the latter was announced at Mobile World Congress that year, no existing hardware was officially supported for a Windows Phone 7 upgrade. Additionally, not a one of the thousands of apps available for Windows Mobile would run unaltered on Windows Phone. The first Windows Mobile 6.5 device was first shown on September 2009, leaked ROMs surfaced in July 2009 for specific devices. The generic ROM images for Mobile 6.5 are also available as part of the officially distributed, several phones running Windows Mobile 6.1 can be updated to Windows Mobile 6.5. Microsofts Windows Mobile 6.1 was announced on April 1,2008, Windows Mobile 6.1 was built upon Windows CE5. Microsofts Windows Mobile 6, internally code-named Crossbow, was released by Microsoft on February 12,2007. Mobile 6 was still based on Windows CE5 and was effectively just a face-lift of Windows Mobile 5, Windows Mobile 5 for Pocket PC was based on Windows CE5 and contained many fixes and improvements over Windows Mobile 2003. Windows Mobile 5.0 solved this problem by storing all data in persistent memory, leaving the RAM to be used only for running applications. As a result, Windows Mobile 5.0 Pocket PCs generally had more flash memory, Pocket PC2000 was launched April 2000, and ran Windows CE3.0. Pocket PC2000 featured a version of Microsoft Office, a chief feature being the ability to password-protect Excel files
