Free and open-source software
Free and open-source software is software that can be classified as both free software and open-source software. That is, anyone is licensed to use, copy and change the software in any way, the source code is shared so that people are encouraged to voluntarily improve the design of the software; this is in contrast to proprietary software, where the software is under restrictive copyright licensing and the source code is hidden from the users. FOSS maintains the software user's civil liberty rights. Other benefits of using FOSS can include decreased software costs, increased security and stability, protecting privacy and giving users more control over their own hardware. Free and open-source operating systems such as Linux and descendants of BSD are utilized today, powering millions of servers, desktops and other devices. Free-software licenses and open-source licenses are used by many software packages; the free-software movement and the open-source software movement are online social movements behind widespread production and adoption of FOSS.
"Free and open-source software" is an umbrella term for software, considered both Free software and open-source software. FOSS allows the user to inspect the source code and provides a high level of control of the software's functions compared to proprietary software; the term "free software" does not refer to the monetary cost of the software at all, but rather whether the license maintains the software user's civil liberties. There are a number of related terms and abbreviations for free and open-source software, or free/libre and open-source software. Although there is a complete overlap between free-software licenses and open-source-software licenses, there is a strong philosophical disagreement between the advocates of these two positions; the terminology of FOSS or "Free and Open-source software" was created to be a neutral on these philosophical disagreements between the FSF and OSI and have a single unified term that could refer to both concepts. As the Free Software Foundation explains the philosophical difference between free software and open-source software: "The two terms describe the same category of software, but they stand for views based on fundamentally different values.
Open-source is a development methodology. For the free-software movement, free software is an ethical imperative, essential respect for the users' freedom. By contrast, the philosophy of open-source considers issues in terms of how to make software “better”—in a practical sense only." In parallel to this the Open Source Initiative considers many free-software licenses to be open source. These include the latest versions of the FSF's three main licenses: the GPL, the Lesser General Public License, the GNU Affero General Public License. Richard Stallman's Free Software Definition, adopted by the Free Software Foundation, defines free software as a matter of liberty not price, it upholds the Four Essential Freedoms; the earliest-known publication of the definition of his free-software idea was in the February 1986 edition of the FSF's now-discontinued GNU's Bulletin publication. The canonical source for the document is in the philosophy section of the GNU Project website; as of August 2017, it is published there in 40 languages.
To meet the definition of "free software", the FSF requires the software's licensing rights what the FSF respect the civil liberties / human rights of what the FSF calls the software user's "Four Essential Freedoms". The freedom to run the program as you wish, for any purpose; the freedom to study how the program works, change it so it does your computing as you wish. Access to the source code is a precondition for this; the freedom to redistribute copies. The freedom to distribute copies of your modified versions to others. By doing this you can give the whole community a chance to benefit from your changes. Access to the source code is a precondition for this; the open-source-software definition is used by the Open Source Initiative to determine whether a software license qualifies for the organization's insignia for Open-source software. The definition was based on the Debian Free Software Guidelines and adapted by Bruce Perens. Perens did not base his writing on the Four Essential Freedoms of free software from the Free Software Foundation, which were only available on the web.
Perens subsequently stated that he felt Eric Raymond's promotion of Open-source unfairly overshadowed the Free Software Foundation's efforts and reaffirmed his support for Free software. In the following 2000s, he spoke about open source again. In the 1950s through the 1980s, it was common for computer users to have the source code for all programs they used, the permission and ability to modify it for their own use. Software, including source code, was shared by individuals who used computers as public domain software. Most companies had a business model based on hardware sales, provided or bundled software with hardware, free of charge. By the late 1960s, the prevailing business model around software was changing. A growing and evolving software industry was competing with the hardware manufacturer's bundled software products. Leased machines required software support while providing n
MacOS is a series of graphical operating systems developed and marketed by Apple Inc. since 2001. It is the primary operating system for Apple's Mac family of computers. Within the market of desktop and home computers, by web usage, it is the second most used desktop OS, after Microsoft Windows.macOS is the second major series of Macintosh operating systems. The first is colloquially called the "classic" Mac OS, introduced in 1984, the final release of, Mac OS 9 in 1999; the first desktop version, Mac OS X 10.0, was released in March 2001, with its first update, 10.1, arriving that year. After this, Apple began naming its releases after big cats, which lasted until OS X 10.8 Mountain Lion. Since OS X 10.9 Mavericks, releases have been named after locations in California. Apple shortened the name to "OS X" in 2012 and changed it to "macOS" in 2016, adopting the nomenclature that they were using for their other operating systems, iOS, watchOS, tvOS; the latest version is macOS Mojave, publicly released in September 2018.
Between 1999 and 2009, Apple sold. The initial version, Mac OS X Server 1.0, was released in 1999 with a user interface similar to Mac OS 8.5. After this, new versions were introduced concurrently with the desktop version of Mac OS X. Beginning with Mac OS X 10.7 Lion, the server functions were made available as a separate package on the Mac App Store.macOS is based on technologies developed between 1985 and 1997 at NeXT, a company that Apple co-founder Steve Jobs created after leaving the company. The "X" in Mac OS X and OS X is pronounced as such; the X was a prominent part of the operating system's brand identity and marketing in its early years, but receded in prominence since the release of Snow Leopard in 2009. UNIX 03 certification was achieved for the Intel version of Mac OS X 10.5 Leopard and all releases from Mac OS X 10.6 Snow Leopard up to the current version have UNIX 03 certification. MacOS shares its Unix-based core, named Darwin, many of its frameworks with iOS, tvOS and watchOS.
A modified version of Mac OS X 10.4 Tiger was used for the first-generation Apple TV. Releases of Mac OS X from 1999 to 2005 ran on the PowerPC-based Macs of that period. After Apple announced that they were switching to Intel CPUs from 2006 onwards, versions were released for 32-bit and 64-bit Intel-based Macs. Versions from Mac OS X 10.7 Lion run on 64-bit Intel CPUs, in contrast to the ARM architecture used on iOS and watchOS devices, do not support PowerPC applications. The heritage of what would become macOS had originated at NeXT, a company founded by Steve Jobs following his departure from Apple in 1985. There, the Unix-like NeXTSTEP operating system was developed, launched in 1989; the kernel of NeXTSTEP is based upon the Mach kernel, developed at Carnegie Mellon University, with additional kernel layers and low-level user space code derived from parts of BSD. Its graphical user interface was built on top of an object-oriented GUI toolkit using the Objective-C programming language. Throughout the early 1990s, Apple had tried to create a "next-generation" OS to succeed its classic Mac OS through the Taligent and Gershwin projects, but all of them were abandoned.
This led Apple to purchase NeXT in 1996, allowing NeXTSTEP called OPENSTEP, to serve as the basis for Apple's next generation operating system. This purchase led to Steve Jobs returning to Apple as an interim, the permanent CEO, shepherding the transformation of the programmer-friendly OPENSTEP into a system that would be adopted by Apple's primary market of home users and creative professionals; the project was first code named "Rhapsody" and officially named Mac OS X. Mac OS X was presented as the tenth major version of Apple's operating system for Macintosh computers. Previous Macintosh operating systems were named using Arabic numerals, as with Mac OS 8 and Mac OS 9; the letter "X" in Mac OS X's name refers to a Roman numeral. It is therefore pronounced "ten" in this context. However, it is commonly pronounced like the letter "X"; the first version of Mac OS X, Mac OS X Server 1.0, was a transitional product, featuring an interface resembling the classic Mac OS, though it was not compatible with software designed for the older system.
Consumer releases of Mac OS X included more backward compatibility. Mac OS applications could be rewritten to run natively via the Carbon API; the consumer version of Mac OS X was launched in 2001 with Mac OS X 10.0. Reviews were variable, with extensive praise for its sophisticated, glossy Aqua interface but criticizing it for sluggish performance. With Apple's popularity at a low, the makers of several classic Mac applications such as FrameMaker and PageMaker declined to develop new versions of their software for Mac OS X. Ars Technica columnist John Siracusa, who reviewed every major OS X release up to 10.10, described the early releases in retrospect as'dog-slow, feature poor' and Aqua as'unbearably slow and a huge resource hog'. Apple developed several new releases of Mac OS X. Siracusa's review of version 10.3, noted "It's strange to have gone from years of uncertainty and vaporware to a steady annual supply of major new operating system releases." Version 10.4, Tiger shocked executives at Microsoft by offering a number of features, such as fast file s
Linux is a family of free and open-source software operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991 by Linus Torvalds. Linux is packaged in a Linux distribution. Distributions include the Linux kernel and supporting system software and libraries, many of which are provided by the GNU Project. Many Linux distributions use the word "Linux" in their name, but the Free Software Foundation uses the name GNU/Linux to emphasize the importance of GNU software, causing some controversy. Popular Linux distributions include Debian and Ubuntu. Commercial distributions include SUSE Linux Enterprise Server. Desktop Linux distributions include a windowing system such as X11 or Wayland, a desktop environment such as GNOME or KDE Plasma. Distributions intended for servers may omit graphics altogether, include a solution stack such as LAMP; because Linux is redistributable, anyone may create a distribution for any purpose. Linux was developed for personal computers based on the Intel x86 architecture, but has since been ported to more platforms than any other operating system.
Linux is the leading operating system on servers and other big iron systems such as mainframe computers, the only OS used on TOP500 supercomputers. It is used by around 2.3 percent of desktop computers. The Chromebook, which runs the Linux kernel-based Chrome OS, dominates the US K–12 education market and represents nearly 20 percent of sub-$300 notebook sales in the US. Linux runs on embedded systems, i.e. devices whose operating system is built into the firmware and is tailored to the system. This includes routers, automation controls, digital video recorders, video game consoles, smartwatches. Many smartphones and tablet computers run other Linux derivatives; because of the dominance of Android on smartphones, Linux has the largest installed base of all general-purpose operating systems. Linux is one of the most prominent examples of open-source software collaboration; the source code may be used and distributed—commercially or non-commercially—by anyone under the terms of its respective licenses, such as the GNU General Public License.
The Unix operating system was conceived and implemented in 1969, at AT&T's Bell Laboratories in the United States by Ken Thompson, Dennis Ritchie, Douglas McIlroy, Joe Ossanna. First released in 1971, Unix was written in assembly language, as was common practice at the time. In a key pioneering approach in 1973, it was rewritten in the C programming language by Dennis Ritchie; the availability of a high-level language implementation of Unix made its porting to different computer platforms easier. Due to an earlier antitrust case forbidding it from entering the computer business, AT&T was required to license the operating system's source code to anyone who asked; as a result, Unix grew and became adopted by academic institutions and businesses. In 1984, AT&T divested itself of Bell Labs; the GNU Project, started in 1983 by Richard Stallman, had the goal of creating a "complete Unix-compatible software system" composed of free software. Work began in 1984. In 1985, Stallman started the Free Software Foundation and wrote the GNU General Public License in 1989.
By the early 1990s, many of the programs required in an operating system were completed, although low-level elements such as device drivers and the kernel, called GNU/Hurd, were stalled and incomplete. Linus Torvalds has stated that if the GNU kernel had been available at the time, he would not have decided to write his own. Although not released until 1992, due to legal complications, development of 386BSD, from which NetBSD, OpenBSD and FreeBSD descended, predated that of Linux. Torvalds has stated that if 386BSD had been available at the time, he would not have created Linux. MINIX was created by Andrew S. Tanenbaum, a computer science professor, released in 1987 as a minimal Unix-like operating system targeted at students and others who wanted to learn the operating system principles. Although the complete source code of MINIX was available, the licensing terms prevented it from being free software until the licensing changed in April 2000. In 1991, while attending the University of Helsinki, Torvalds became curious about operating systems.
Frustrated by the licensing of MINIX, which at the time limited it to educational use only, he began to work on his own operating system kernel, which became the Linux kernel. Torvalds began the development of the Linux kernel on MINIX and applications written for MINIX were used on Linux. Linux matured and further Linux kernel development took place on Linux systems. GNU applications replaced all MINIX components, because it was advantageous to use the available code from the GNU Project with the fledgling operating system. Torvalds initiated a switch from his original license, which prohibited commercial redistribution, to the GNU GPL. Developers worked to integrate GNU components with the Linux kernel, making a functional and free operating system. Linus Torvalds had wanted to call his invention "Freax", a portmant
Microsoft Windows is a group of several graphical operating system families, all of which are developed and sold by Microsoft. Each family caters to a certain sector of the computing industry. Active Windows families include Windows Embedded. Defunct Windows families include Windows Mobile and Windows Phone. Microsoft introduced an operating environment named Windows on November 20, 1985, as a graphical operating system shell for MS-DOS in response to the growing interest in graphical user interfaces. Microsoft Windows came to dominate the world's personal computer market with over 90% market share, overtaking Mac OS, introduced in 1984. Apple came to see Windows as an unfair encroachment on their innovation in GUI development as implemented on products such as the Lisa and Macintosh. On PCs, Windows is still the most popular operating system. However, in 2014, Microsoft admitted losing the majority of the overall operating system market to Android, because of the massive growth in sales of Android smartphones.
In 2014, the number of Windows devices sold was less than 25 %. This comparison however may not be relevant, as the two operating systems traditionally target different platforms. Still, numbers for server use of Windows show one third market share, similar to that for end user use; as of October 2018, the most recent version of Windows for PCs, tablets and embedded devices is Windows 10. The most recent versions for server computers is Windows Server 2019. A specialized version of Windows runs on the Xbox One video game console. Microsoft, the developer of Windows, has registered several trademarks, each of which denote a family of Windows operating systems that target a specific sector of the computing industry; as of 2014, the following Windows families are being developed: Windows NT: Started as a family of operating systems with Windows NT 3.1, an operating system for server computers and workstations. It now consists of three operating system subfamilies that are released at the same time and share the same kernel: Windows: The operating system for mainstream personal computers and smartphones.
The latest version is Windows 10. The main competitor of this family is macOS by Apple for personal computers and Android for mobile devices. Windows Server: The operating system for server computers; the latest version is Windows Server 2019. Unlike its client sibling, it has adopted a strong naming scheme; the main competitor of this family is Linux. Windows PE: A lightweight version of its Windows sibling, meant to operate as a live operating system, used for installing Windows on bare-metal computers, recovery or troubleshooting purposes; the latest version is Windows PE 10. Windows IoT: Initially, Microsoft developed Windows CE as a general-purpose operating system for every device, too resource-limited to be called a full-fledged computer. However, Windows CE was renamed Windows Embedded Compact and was folded under Windows Compact trademark which consists of Windows Embedded Industry, Windows Embedded Professional, Windows Embedded Standard, Windows Embedded Handheld and Windows Embedded Automotive.
The following Windows families are no longer being developed: Windows 9x: An operating system that targeted consumers market. Discontinued because of suboptimal performance. Microsoft now caters to the consumer market with Windows NT. Windows Mobile: The predecessor to Windows Phone, it was a mobile phone operating system; the first version was called Pocket PC 2000. The last version is Windows Mobile 6.5. Windows Phone: An operating system sold only to manufacturers of smartphones; the first version was Windows Phone 7, followed by Windows Phone 8, the last version Windows Phone 8.1. It was succeeded by Windows 10 Mobile; the term Windows collectively describes any or all of several generations of Microsoft operating system products. These products are categorized as follows: The history of Windows dates back to 1981, when Microsoft started work on a program called "Interface Manager", it was announced in November 1983 under the name "Windows", but Windows 1.0 was not released until November 1985.
Windows 1.0 was to achieved little popularity. Windows 1.0 is not a complete operating system. The shell of Windows 1.0 is a program known as the MS-DOS Executive. Components included Calculator, Cardfile, Clipboard viewer, Control Panel, Paint, Reversi and Write. Windows 1.0 does not allow overlapping windows. Instead all windows are tiled. Only modal dialog boxes may appear over other windows. Microsoft sold as included Windows Development libraries with the C development environment, which included numerous windows samples. Windows 2.0 was released in December 1987, was more popular than its predecessor. It features several improvements to the user memory management. Windows 2.03 changed the OS from tiled windows to overlapping windows. The result of this change led to Apple Computer filing a suit against Microsoft alleging infringement on Apple's copyrights. Windows 2.0
A light-emitting diode is a semiconductor light source that emits light when current flows through it. Electrons in the semiconductor recombine with electron holes, releasing energy in the form of photons; this effect is called electroluminescence. The color of the light is determined by the energy required for electrons to cross the band gap of the semiconductor. White light is obtained by using multiple semiconductors or a layer of light-emitting phosphor on the semiconductor device. Appearing as practical electronic components in 1962, the earliest LEDs emitted low-intensity infrared light. Infrared LEDs are used in remote-control circuits, such as those used with a wide variety of consumer electronics; the first visible-light LEDs were of low intensity and limited to red. Modern LEDs are available across the visible and infrared wavelengths, with high light output. Early LEDs were used as indicator lamps, replacing small incandescent bulbs, in seven-segment displays. Recent developments have produced white-light LEDs suitable for room lighting.
LEDs have led to new displays and sensors, while their high switching rates are useful in advanced communications technology. LEDs have many advantages over incandescent light sources, including lower energy consumption, longer lifetime, improved physical robustness, smaller size, faster switching. Light-emitting diodes are used in applications as diverse as aviation lighting, automotive headlamps, general lighting, traffic signals, camera flashes, lighted wallpaper and medical devices. Unlike a laser, the color of light emitted from an LED is neither coherent nor monochromatic, but the spectrum is narrow with respect to human vision, functionally monochromatic. Electroluminescence as a phenomenon was discovered in 1907 by the British experimenter H. J. Round of Marconi Labs, using a crystal of silicon carbide and a cat's-whisker detector. Russian inventor Oleg Losev reported creation of the first LED in 1927, his research was distributed in Soviet and British scientific journals, but no practical use was made of the discovery for several decades.
In 1936, Georges Destriau observed that electroluminescence could be produced when zinc sulphide powder is suspended in an insulator and an alternating electrical field is applied to it. In his publications, Destriau referred to luminescence as Losev-Light. Destriau worked in the laboratories of Madame Marie Curie an early pioneer in the field of luminescence with research on radium. Hungarian Zoltán Bay together with György Szigeti pre-empted led lighting in Hungary in 1939 by patented a lighting device based on SiC, with an option on boron carbide, that emmitted white, yellowish white, or greenish white depending on impurities present. Kurt Lehovec, Carl Accardo, Edward Jamgochian explained these first light-emitting diodes in 1951 using an apparatus employing SiC crystals with a current source of battery or pulse generator and with a comparison to a variant, crystal in 1953. Rubin Braunstein of the Radio Corporation of America reported on infrared emission from gallium arsenide and other semiconductor alloys in 1955.
Braunstein observed infrared emission generated by simple diode structures using gallium antimonide, GaAs, indium phosphide, silicon-germanium alloys at room temperature and at 77 kelvins. In 1957, Braunstein further demonstrated that the rudimentary devices could be used for non-radio communication across a short distance; as noted by Kroemer Braunstein "…had set up a simple optical communications link: Music emerging from a record player was used via suitable electronics to modulate the forward current of a GaAs diode. The emitted light was detected by a PbS diode some distance away; this signal was played back by a loudspeaker. Intercepting the beam stopped the music. We had a great deal of fun playing with this setup." This setup presaged the use of LEDs for optical communication applications. In September 1961, while working at Texas Instruments in Dallas, James R. Biard and Gary Pittman discovered near-infrared light emission from a tunnel diode they had constructed on a GaAs substrate. By October 1961, they had demonstrated efficient light emission and signal coupling between a GaAs p-n junction light emitter and an electrically isolated semiconductor photodetector.
On August 8, 1962, Biard and Pittman filed a patent titled "Semiconductor Radiant Diode" based on their findings, which described a zinc-diffused p–n junction LED with a spaced cathode contact to allow for efficient emission of infrared light under forward bias. After establishing the priority of their work based on engineering notebooks predating submissions from G. E. Labs, RCA Research Labs, IBM Research Labs, Bell Labs, Lincoln Lab at MIT, the U. S. patent office issued the two inventors the patent for the GaAs infrared light-emitting diode, the first practical LED. After filing the patent, Texas Instruments began a project to manufacture infrared diodes. In October 1962, TI announced the first commercial LED product, which employed a pure GaAs crystal to emit an 890 nm light output. In October 1963, TI announced the first commercial hemispherical LED, the SNX-110; the first visible-spectrum LED was developed in 1962 by Nick Holonyak, Jr. while working at General Electric. Holonyak first reported his LED in the journal Applied Physics Letters on December 1, 1962.
M. George Craford, a former graduate student of Holonyak, invented the first yellow LED and improved the brightness of red and red-orange LEDs by a factor of ten in 1972. In 1976, T. P. Pearsall created the first high-brightness, high-efficiency LEDs for optical fiber telecommunicat
A newsreader is an application program that reads articles on Usenet. Newsreaders act as clients which connect to a news server, via the Network News Transfer Protocol, to download articles and post new articles. In addition to text-based articles, Usenet is used to distribute binary files in dedicated "binaries" newsgroups; the term newsreader is sometimes used interchangeably with news aggregator. Newsreaders that help users to adhere to the established conventions of Usenet, known as netiquette, are evaluated by the Good Netkeeping Seal of Approval. There are several different types of newsreaders, depending on the type of service the user needs—whether intended for discussion or for downloading files posted to the alt.binaries hierarchy: Desktop newsreaders Designed to integrate well with common GUI environments, integrated with a web browser or email client. Examples: Windows Live Mail, Mozilla Thunderbird, Forté Agent, Unison and Pan. Traditional newsreaders Designed for reading/posting text posts.
Gnus, as well as more specialized newsreaders such as slrn, nn and tin. Binary downloaders Although Usenet started as a text-based messaging system without any file attachment ability, many Usenet users today do not participate in discussion groups, as was common during the 1980s and 1990s and only use Newsgroups for downloading files such as music, pornography and games. Therefore, their needs call for a streamlined client for grabbing binary attachments, without the extraneous clutter of text reading and posting features for which file downloaders have little use. Examples: GrabIt, NewsBin List of Usenet newsreaders Comparison of Usenet newsreaders
Unix is a family of multitasking, multiuser computer operating systems that derive from the original AT&T Unix, development starting in the 1970s at the Bell Labs research center by Ken Thompson, Dennis Ritchie, others. Intended for use inside the Bell System, AT&T licensed Unix to outside parties in the late 1970s, leading to a variety of both academic and commercial Unix variants from vendors including University of California, Microsoft, IBM, Sun Microsystems. In the early 1990s, AT&T sold its rights in Unix to Novell, which sold its Unix business to the Santa Cruz Operation in 1995; the UNIX trademark passed to The Open Group, a neutral industry consortium, which allows the use of the mark for certified operating systems that comply with the Single UNIX Specification. As of 2014, the Unix version with the largest installed base is Apple's macOS. Unix systems are characterized by a modular design, sometimes called the "Unix philosophy"; this concept entails that the operating system provides a set of simple tools that each performs a limited, well-defined function, with a unified filesystem as the main means of communication, a shell scripting and command language to combine the tools to perform complex workflows.
Unix distinguishes itself from its predecessors as the first portable operating system: the entire operating system is written in the C programming language, thus allowing Unix to reach numerous platforms. Unix was meant to be a convenient platform for programmers developing software to be run on it and on other systems, rather than for non-programmers; the system grew larger as the operating system started spreading in academic circles, as users added their own tools to the system and shared them with colleagues. At first, Unix was not designed to be multi-tasking. Unix gained portability, multi-tasking and multi-user capabilities in a time-sharing configuration. Unix systems are characterized by various concepts: the use of plain text for storing data; these concepts are collectively known as the "Unix philosophy". Brian Kernighan and Rob Pike summarize this in The Unix Programming Environment as "the idea that the power of a system comes more from the relationships among programs than from the programs themselves".
In an era when a standard computer consisted of a hard disk for storage and a data terminal for input and output, the Unix file model worked quite well, as I/O was linear. In the 1980s, non-blocking I/O and the set of inter-process communication mechanisms were augmented with Unix domain sockets, shared memory, message queues, semaphores, network sockets were added to support communication with other hosts; as graphical user interfaces developed, the file model proved inadequate to the task of handling asynchronous events such as those generated by a mouse. By the early 1980s, users began seeing Unix as a potential universal operating system, suitable for computers of all sizes; the Unix environment and the client–server program model were essential elements in the development of the Internet and the reshaping of computing as centered in networks rather than in individual computers. Both Unix and the C programming language were developed by AT&T and distributed to government and academic institutions, which led to both being ported to a wider variety of machine families than any other operating system.
Under Unix, the operating system consists of many libraries and utilities along with the master control program, the kernel. The kernel provides services to start and stop programs, handles the file system and other common "low-level" tasks that most programs share, schedules access to avoid conflicts when programs try to access the same resource or device simultaneously. To mediate such access, the kernel has special rights, reflected in the division between user space and kernel space - although in microkernel implementations, like MINIX or Redox, functions such as network protocols may run in user space; the origins of Unix date back to the mid-1960s when the Massachusetts Institute of Technology, Bell Labs, General Electric were developing Multics, a time-sharing operating system for the GE-645 mainframe computer. Multics featured several innovations, but presented severe problems. Frustrated by the size and complexity of Multics, but not by its goals, individual researchers at Bell Labs started withdrawing from the project.
The last to leave were Ken Thompson, Dennis Ritchie, Douglas McIlroy, Joe Ossanna, who decided to reimplement their experiences in a new project of smaller scale. This new operating system was without organizational backing, without a name; the new operating system was a single-tasking system. In 1970, the group coined the name Unics for Uniplexed Information and Computing Service, as a pun on Multics, which stood for Multiplexed Information and Computer Services. Brian Kernighan takes credit for the idea, but adds that "no one can remember" the origin of the final spelling Unix. Dennis Ritchie, Doug McIlroy, Peter G. Neumann credit Kernighan; the operating system was written in assembly language, but in 1973, Version 4 Unix was rewritten in C. Version 4 Unix, still had many PDP-11 dependent codes, is not suitable for porting; the first port to other platform was made five years f