Automated guideway transit refers to guided transit vehicles operating singly or in multi-car trains with fully automated control (no crew on transit units). Service may be on a fixed schedule or in response to a passenger-activated call button. Automated guideway transit includes personal rapid transit, group rapid transit and people mover systems.

Personal rapid transit (PRT), also called personal automated transport (PAT), is a public transportation concept that offers on-demand, non-stop transportation, using small, independent vehicles on a network of specially-built guideways.

People mover or automated people mover (APM) systems are fully automated, grade-separated mass transit systems which serve a relatively small area such as an airport, downtown district or theme park. The term “people mover” has become generic for the type of system, which may use technologies such as monorail, duorail, automated guideway transit or maglev.

Monorail means a system of guided transit vehicles operating on or suspended from a single rail, beam, or tube. Usually they operate in trains. Monorails are distinguished from other types of elevated rail system by their use of only a single beam, and from light rail and tram systems by the fact they are always grade separated from other vehicles and pedestrians.

Adapted from the Wikipedia article Passenger rail terminology, under the G. N. U. Free Documentation License. Please also see http://en.wikipedia.org/wiki

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Mac OS X users can accomplish this by holding down Command-S after powering the system. The user may be required to enter a password set in the firmware. Single User Mode is different from a Safe Mode boot in that the system goes directly to the console instead of starting up the core elements of Mac OS X (items in /System/Library/, ignoring /Library/, ~/Library/, et al.). From there users are encouraged by a prompt to run fsck or other command line utilities as needed (or installed).

Adapted from the Wikipedia article Single user mode, under the G. N. U. Free Documentation License. Please also see http://en.wikipedia.org/wiki

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Many users and developers of BSD-based operating systems have a different position on licensing. The main difference is the belief that the copyleft licences, particularly the GNU General Public License (GPL), are undesirably complicated and/or restrictive. The GPL requires any derivative work that is released to be released according to the GPL while the BSD licence does not. Essentially, the BSD license’s only requirement is to acknowledge the original authors, and poses no restrictions on how the source code may be used. As a result, BSD code can be used in proprietary software that only acknowledges the authors. For instance, the IP stack in Microsoft Windows and Mac OS X are derived from BSD-licensed software.

Supporters of the BSD licence argue that it is more free than the GPL because it grants the right to do anything with the source code, second only to software in the public domain. This includes incorporating the BSD-licensed code in proprietary products. The approach has led to BSD code being used in common, widely used commercial software. In response, GPL supporters claim that the freedom of others to make non-free software from free software is an unjust form of power rather than a necessary freedom. However, some developers might want to include GPLed software in their products and can’t do it, simply because the GPL is incompatible with the licences of other software they include in their product, even if everything is open source.

Code licensed under a permissive free software licence, such as the BSD licence, can be incorporated into copylefted (e.g. GPL’d) projects. Such code is thus “GPL-compatible”. There is no need to secure the consent of the original authors. In contrast, code under the GPL cannot be relicensed under the BSD licence without securing the consent of all copyright holders. Thus the two licences are compatible, but the combination as a whole must be distributed under the terms of the GPL, not the permissive licence.

Existing free software BSDs tend to avoid including software licenced under the GPL in the core operating system, or the ”base system”, except as a last resort when alternatives are non-existent or vastly less capable, such as with GCC. (Indeed however, note that as of mid 2010 Apple for example are moving from GCC to the upcoming LLVM compiler, perhaps primarily for this reason.) The OpenBSD project has acted to remove GPL-licensed tools in favor of BSD-licensed alternatives, some newly written and some adapted from older code.

Adapted from the Wikipedia article Free software licence, under the G. N. U. Free Documentation License. Please also see http://en.wikipedia.org/wiki

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OKL4 Microvisor

[http://okl4.org OKL4] is an open source system software platform for embedded systems that can be used as a hypervisor as well as a simple real-time operating system with memory protection. The OKL4 “microvisor” is based upon the L4 microkernel. OKL4 is a Type I Embedded Hypervisor and runs on single- and multi-core platforms based on ARM, x86 and MIPS processors.

OKL4 has been deployed on over 300 million devices, mostly mobile phones, both as a baseband operating system and for hosting guest operating systems. Most notable and visible is the company’s design win at Motorola for the [http://www.motorola.com/consumers/US-EN/Motorola-Evoke-QA4-US-EN.do?vgnextoid=56cbe25ab7e7f110VgnVCM1000008406b00aRCRD Evoke QA4 messaging phone], the first phone which employs virtualization to support two concurrent operating systems (Linux and BREW) on a single processor core.

Paravirtualized Guest OSes

OK Labs also supplies ready-to-integrate paravirtualized guest application operating systems, including OK:Symbian (SymbianOS), OK:Linux (Linux) and OK:Android (Android).

Adapted from the Wikipedia article Open Kernel Labs, under the G. N. U. Free Documentation License. Please also see http://en.wikipedia.org/wiki

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Gossip is an instant messaging client for Unix-like operating systems. It uses XMPP protocol and adheres to GNOME’s published human interface guidelines. It is written in the C programming language, and its main developer is Mikael Hallendal, founder of Imendio.

Adapted from the Wikipedia article Gossip (software), under the G. N. U. Free Documentation License. Please also see http://en.wikipedia.org/wiki

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Client-side scripts are often embedded within an HTML document (hence known as an “embedded script”), but they may also be contained in a separate file, which is referenced by the document (or documents) that use it (hence known as an “external script”). Upon request, the necessary files are sent to the user’s computer by the web server (or servers) on which they reside. The user’s web browser executes the script, then displays the document, including any visible output from the script. Client-side scripts may also contain instructions for the browser to follow in response to certain user actions, (e.g., clicking a button). Often, these instructions can be followed without further communication with the server.

By viewing the file that contains the script, users may be able to see its source code. Many web authors learn how to write client-side scripts partly by examining the source code for other authors’ scripts.

In contrast, server-side scripts, written in languages such as Perl, PHP, and server-side VBScript, are executed by the web server when the user requests a document. They produce output in a format understandable by web browsers (usually HTML), which is then sent to the user’s computer. The user cannot see the script’s source code (unless the author publishes the code separately), and may not even be aware that a script was executed. Documents produced by server-side scripts may, in turn, contain client-side scripts.

Client-side scripts have greater access to the information and functions available on the user’s browser, whereas server-side scripts have greater access to the information and functions available on the server. Server-side scripts require that their language’s interpreter be installed on the server, and produce the same output regardless of the client’s browser, operating system, or other system details. Client-side scripts do not require additional software on the server (making them popular with authors who lack administrative access to their servers); however, they do require that the user’s web browser understands the scripting language in which they are written. It is therefore impractical for an author to write scripts in a language that is not supported by popular web browsers.

Due to security restrictions, client-side scripts may not be allowed to access the user’s computer beyond the web browser application. Techniques like ActiveX controls can be used to sidestep this restriction.

Unfortunately, even languages that are supported by a wide variety of browsers may not be implemented in precisely the same way across all browsers and operating systems. Authors are well-advised to review the behavior of their client-side scripts on a variety of platforms before they put them into use.

Adapted from the Wikipedia article Client-side scripting, under the G. N. U. Free Documentation License. Please also see http://en.wikipedia.org/wiki

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KTouch is a software application written for the KDE SC desktop environment that drills students in the method of touch typing. It comes with lessons for many different keyboard layouts across many different languages. It also has exercises for learning to use a number pad. As the user types, it keeps real-time statistics of how well they do. If the user does well enough, KTouch moves up to the next lesson. The user can also manually advance to the next lesson themselves.

Adapted from the Wikipedia article KTouch, under the G. N. U. Free Documentation License. Please also see http://en.wikipedia.org/wiki

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*Cone, a text-based e-mail and news client for Unix-like operating systems

*Cone tracing, a derivative of the ray tracing algorithm that replaces rays, which have no thickness, with cones

*Second-order cone programming a library of routines that implements a predictor corrector variant of the semidefinite programming algorithm

Adapted from the Wikipedia article Cone, under the G. N. U. Free Documentation License. Please also see http://en.wikipedia.org/wiki

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The MIT License is similar to the 3-clause “modified” BSD license, except that the BSD license contains a notice prohibiting the use of the name of the copyright holder in promotion. This is sometimes present in versions of the MIT License, as noted above.

The original BSD license also includes a clause requiring all advertising of the software to display a notice crediting its authors. This “advertising clause” (since disavowed by UC Berkeley) is present in the modified MIT License used by XFree86.

The MIT License states more explicitly the rights given to the end-user, including the right to use, copy, modify, merge, publish, distribute, sublicense, and/or sell the software.

A 2-clause BSD-style license used by FreeBSD (and preferred for NetBSD) is essentially identical to the MIT License, as it contains neither an advertising clause, nor a prohibition on promotional use of the copyright holder’s name.

Also similar in terms is the ISC license, which has a simpler language.

The University of Illinois/NCSA Open Source License combines text from both the MIT and BSD licenses; the license grant and disclaimer are taken from the MIT License.

Adapted from the Wikipedia article MIT License, under the G. N. U. Free Documentation License. Please also see http://en.wikipedia.org/wiki

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In 1986, DEC added VAXclustering support to their MicroVAX minicomputers, running over Ethernet instead of special-purpose hardware. While not giving the high-availability advantages of the CI hardware, these ”Local Area VAXclusters” provided an attractive expansion path for buyers of low-end minicomputers.

Later versions of OpenVMS (V5.0 and later) supported “mixed interconect” VAXclusters (using both CI and Ethernet), and VAXclustering over DSSI (Digital Systems and Storage Interconnect) and FDDI, among other transports. Eventually, as high-bandwidth wide area networking became available, clustering was extended to allow satellite data links and long-distance terrestrial links. This allowed the creation of ”disaster-tolerant clusters”; by locating the single VAXcluster in several diverse geographical areas, the cluster could survive infrastructure failures and natural disasters.

VAXclustering was greatly aided by the introduction of terminal servers using the LAT protocol. By allowing ordinary serial terminals to access the host nodes via Ethernet, it became possible for any terminal to rapidly and easily connect to any host node. This made it much simpler to accomplish fail over of the user terminals from one node of the cluster to another.

Eventually, VAXclusters reached the point where the cluster as a whole essentially never went down. ”Rolling upgrades” even allowed the system operators to upgrade the OpenVMS system software, shutting down, upgrading, and rebooting individual nodes while the cluster as a whole continued processing. Cluster uptimes are frequently measured in years with the current longest uptime being at least twelve years.

As mentioned above, OpenVMS now also runs on Alpha and IA-64 systems, so the term ”VAXcluster” has been replaced by ”VMScluster”. With Gigabit Ethernet now common and 10-gigabit Ethernet being introduced, standard networking cables and cards are quite sufficient to support VMSclustering.

Adapted from the Wikipedia article VMScluster, under the G. N. U. Free Documentation License. Please also see http://en.wikipedia.org/wiki

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