You are looking at all articles with the topic "computing". We found 523 matches.

Hint: To view all topics, click here. Too see the most popular topics, click here instead.

In computing, a pizza box is a style of case design for desktop computers or network switches. Pizza box cases tend to be wide and flat, normally 1.5 to 4 inches or 4 to 10 centimetres in height, resembling pizza delivery boxes and thus the name. This is in contrast to a tower system, whose case height is much greater than the width and has an "upright" appearance. In modern usage, the term "pizza box" is normally reserved for very flat cases with height no more than 2 inches (51 mm), while those taller than 2 inches are referred to as desktop cases instead.

The common setup of a pizza box system is to have the display monitor placed directly on top of the case, which serves as a podium to elevate the monitor more towards the user's eye level, and to have other peripherals placed in front and alongside the case. Occasionally, the pizza box may be laid on its sides in a tower-like orientation.

Data General's Aviion Unix server was the first to coin the expression when it advertised in 1991 with the tagline "Who just fit mainframe power in a pizza box?", but most computers generally referred to as pizza box systems were high-end desktop systems such as Sun Microsystems workstations sold in the 1990s, most notably the SPARCstation 1 and SPARCstation 5. Other notable examples have been among the highest-performing desktop computers of their generations, including the SGI Indy, the NeXTstation, and the Amiga 1000, but the form factor was also seen in budget and lower-end lines such as the Macintosh LC family.

The original SPARCstation 1 design included an expansion bus technology, SBus, expressly designed for the form factor; expansion cards were small, especially in comparison to other expansion cards in use at the time such as VMEbus, and were mounted horizontally instead of vertically. PC-compatible computers in this type of case typically use the PCI expansion bus and are usually either a) limited to one or two horizontally placed expansion cards or b) require special low-profile expansion cards, shorter than the PCI cards regular PCs use.

The density of computing power and stackability of pizza box systems also made them attractive for use in data centers. Systems originally designed for desktop use were placed on shelves inside of 19-inch racks, sometimes requiring that part of their cases be cut off for them to fit. Since the late 1990s, pizza boxes have been a common form factor in office cubicles, data centers or industrial applications, where desktop space, rack room and density are critical. Servers in this form factor, as well as higher-end Ethernet switches, are now designed for rack mounting. Rack mount 1U computers come in all types of configurations and depths.

The pizza box form factor for smaller personal systems and thin clients remains in use well into the 21st century, though it is increasingly being superseded by laptops, nettops or All-in-One PC designs that embed the already size-reduced computer onto the keyboard or display monitor.

In computer programming, a poltergeist (or gypsy wagon) is a short-lived, typically stateless object used to perform initialization or to invoke methods in another, more permanent class. It is considered an anti-pattern. The original definition is by Michael Akroyd 1996 - Object World West Conference:

"As a gypsy wagon or a poltergeist appears and disappears mysteriously, so does this short lived object. As a consequence the code is more difficult to maintain and there is unnecessary resource waste. The typical cause for this anti-pattern is poor object design."

A poltergeist can often be identified by its name; they are often called "manager_", "controller_", "supervisor", "start_process", etc.

Sometimes, poltergeist classes are created because the programmer anticipated the need for a more complex architecture. For example, a poltergeist arises if the same method acts as both the client and invoker in a command pattern, and the programmer anticipates separating the two phases. However, this more complex architecture may actually never materialize.

Poltergeists should not be confused with long-lived, state-bearing objects of a pattern such as model–view–controller, or tier-separating patterns such as business-delegate.

To remove a poltergeist, delete the class and insert its functionality in the invoked class, possibly by inheritance or as a mixin.

The X Window System (X11, or simply X) is a windowing system for bitmap displays, common on Unix-like operating systems.

X provides the basic framework for a GUI environment: drawing and moving windows on the display device and interacting with a mouse and keyboard. X does not mandate the user interface – this is handled by individual programs. As such, the visual styling of X-based environments varies greatly; different programs may present radically different interfaces.

X originated as part of Project Athena at Massachusetts Institute of Technology (MIT) in 1984. The X protocol has been at version 11 (hence "X11") since September 1987. The X.Org Foundation leads the X project, with the current reference implementation, X.Org Server, available as free and open-source software under the MIT License and similar permissive licenses.

Extreme programming (XP) is a software development methodology intended to improve software quality and responsiveness to changing customer requirements. As a type of agile software development, it advocates frequent releases in short development cycles, intended to improve productivity and introduce checkpoints at which new customer requirements can be adopted.

Other elements of extreme programming include programming in pairs or doing extensive code review, unit testing of all code, not programming features until they are actually needed, a flat management structure, code simplicity and clarity, expecting changes in the customer's requirements as time passes and the problem is better understood, and frequent communication with the customer and among programmers. The methodology takes its name from the idea that the beneficial elements of traditional software engineering practices are taken to "extreme" levels. As an example, code reviews are considered a beneficial practice; taken to the extreme, code can be reviewed continuously (i.e. the practice of pair programming).

.aq is the Internet country code top-level domain (ccTLD) for Antarctica (itself not a country). It is derived from the French Antarctique and is reserved for organizations that work in Antarctica or promote the Antarctic and Southern Ocean regions. It is administered by Peter Mott of Antarctica Network Information Centre Limited from Christchurch, New Zealand.

.aq domain names are available free of charge, and registration is granted for a period of 24 months. As a general rule, registrants are only allocated a single .aq domain name. The registry does not have a website. Registration is only possible by contacting Antarctica Network Information Centre Limited.

A cross compiler is a compiler capable of creating executable code for a platform other than the one on which the compiler is running. For example, a compiler that runs on a PC but generates code that runs on Android devices is a cross compiler.

A cross compiler is useful to compile code for multiple platforms from one development host. Direct compilation on the target platform might be infeasible, for example on embedded systems with limited computing resources.

Cross compilers are distinct from source-to-source compilers. A cross compiler is for cross-platform software generation of machine code, while a source-to-source compiler translates from one coding language to another in text code. Both are programming tools.

Cargo cult programming is a style of computer programming characterized by the ritual inclusion of code or program structures that serve no real purpose. Cargo cult programming is symptomatic of a programmer not understanding either a bug they were attempting to solve or the apparent solution (compare shotgun debugging, deep magic). The term cargo cult programmer may apply when an unskilled or novice computer programmer (or one inexperienced with the problem at hand) copies some program code from one place to another with little understanding of how it works or whether it is required.

Cargo cult programming can also refer to the practice of applying a design pattern or coding style blindly without understanding the reasons behind that design principle. Examples being adding unnecessary comments to self-explanatory code, overzealous adherence to the conventions of a programming paradigm, or adding deletion code for objects that garbage collection automatically collect.

Obsessive and redundant checks for null values or testing whether a collection is empty before iterating its values may be a sign of cargo cult programming. Such obsessive checks make the code less readable, and often prevent the output of proper error messages, obscuring the real cause of a misbehaving program.

FILE_ID.DIZ is a plain text file containing a brief content description of the archive in which it is included. It was originally used in archives distributed through bulletin board systems (BBS), and still in the warez scene.

Bulletin boards commonly accept uploaded files from their users. The BBS software would prompt the user to supply a description for the uploaded file, but these descriptions were often less than useful. BBS system operators spent many hours going over the upload descriptions correcting and editing the descriptions. The FILE_ID.DIZ inclusion in archives was designed to address this problem.

FILE_ID stands for "file identification". DIZ stands for Description In Zipfile.

Clark Development and the Association of Shareware Professionals supported the idea of this becoming a standard for file descriptions. Clark rewrote the PCBDescribe program and included it with their PCBoard BBS software. The ASP urged their members to use this description file format in their distributions. Michael Leavitt, an employee of Clark Development, released the file specification and his PCBDescribe program source code to the public domain and urged other BBS software companies to support the DIZ file.

SysOps could add a common third-party script written in PPL, called "DIZ/2-PCB" that would process, rewrite, verify, and format DIZ files from archives as they were uploaded to a BBS. The software would extract the archive, examine the contents, compile a report, import the DIZ description file and then format it according to your liking. During this time, it was usual practice to add additional lines to the description, such as ads exclaiming the source of the uploaded BBS.

Traditionally, a FILE_ID.DIZ should be "up to 10 lines of text, each line being no more than 45 characters long." according to the specification v1.9.

The concept of DIZ files was to allow a concise description of uploaded files to be automatically applied. Advertisements and "high ASCII" artwork were specifically prohibited.

Even since the decline of the dial-up bulletin board system, FILE_ID.DIZ files are still utilized by the warez scene in their releases of unlicensed software. They are commonly bundled as part of the complete packaging by self-described pirate groups, and indicate the number of disks, and other basic information. Along with the NFO file, it is essential to the release. Especially in terms of unlicensed software ("warez"), it was common for each file in a sequential compressed archive (an archive intentionally split into multiple parts at creation so the parts can then be individually downloaded by slower connections like dial-up. Example: .rar, .r00, .r01, .r02, etc.), to contain this file. This probably contributed to its extended popularity after the decline of the bulletin board system in the late 1990s and early 2000s until now, since even casual consumers of unlicensed software would have stumbled upon it due to its abundance.

The fundamental theorem of software engineering (FTSE) is a term originated by Andrew Koenig to describe a remark by Butler Lampson attributed to the late David J. Wheeler:

"We can solve any problem by introducing an extra level of indirection."

The theorem does not describe an actual theorem that can be proven; rather, it is a general principle for managing complexity through abstraction.

The theorem is often expanded by the humorous clause "…except for the problem of too many levels of indirection," referring to the fact that too many abstractions may create intrinsic complexity issues of their own. For example, the use of protocol layering in computer networks, which today is ubiquitous, has been criticized in ways that are typical of more general disadvantages of abstraction. Here, the adding of extra levels of indirection may cause higher layers to duplicate the functionality of lower layers, leading to inefficiency, and functionality at one layer may need data present only at another layer, which fundamentally violates the goal of separation into different layers.

PAQ is a series of lossless data compression archivers that have gone through collaborative development to top rankings on several benchmarks measuring compression ratio (although at the expense of speed and memory usage). Specialized versions of PAQ have won the Hutter Prize and the Calgary Challenge. PAQ is free software distributed under the GNU General Public License.