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Digital Command Language
DIGITAL Command Language (DCL) is the standard command language adopted by many of the operating systems created by Digital Equipment Corporation. DCL had its roots in IAS, TOPS-20, and RT-11 and was implemented as a standard across most of Digital's operating systems, notably RSX-11 and RSTS/E, but took its most powerful form in VAX/VMS (later OpenVMS). DCL continues to be developed by VSI as part of OpenVMS. Written when the programming language Fortran was in heavy use, DCL is a scripting language supporting several datatypes, including strings, integers, bit arrays, arrays and booleans, but not floating point numbers. Access to OpenVMS ''system services'' ( kernel API) is through lexical functions, which perform the same as their compiled language counterparts and allow scripts to get information on system state. DCL includes IF-THEN-ELSE, access to all the Record Management Services (RMS) file types including stream, indexed, and sequential, but unfortunately lacks a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Imperative Programming
In computer science, imperative programming is a programming paradigm of software that uses statements that change a program's state. In much the same way that the imperative mood in natural languages expresses commands, an imperative program consists of commands for the computer to perform. Imperative programming focuses on describing ''how'' a program operates step by step, rather than on high-level descriptions of its expected results. The term is often used in contrast to declarative programming, which focuses on ''what'' the program should accomplish without specifying all the details of ''how'' the program should achieve the result. Imperative and procedural programming Procedural programming is a type of imperative programming in which the program is built from one or more procedures (also termed subroutines or functions). The terms are often used as synonyms, but the use of procedures has a dramatic effect on how imperative programs appear and how they are constructed ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Array Data Type
In computer science, array is a data type that represents a collection of ''elements'' (value (computer science), values or variable (computer science), variables), each selected by one or more indices (identifying keys) that can be computed at Run time (program lifecycle phase), run time during program execution. Such a collection is usually called an array variable or array value.Robert W. Sebesta (2001) ''Concepts of Programming Languages''. Addison-Wesley. 4th edition (1998), 5th edition (2001), By analogy with the mathematical concepts vector (mathematics), vector and matrix (mathematics), matrix, array types with one and two indices are often called vector type and matrix type, respectively. More generally, a multidimensional array type can be called a tensor type, by anology with the physical concept, tensor. Language support for array types may include certain built-in type, built-in array data types, some syntactic constructions (''array type constructors'') that the p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
GitHub
GitHub, Inc. () is an Internet hosting service for software development and version control using Git. It provides the distributed version control of Git plus access control, bug tracking, software feature requests, task management, continuous integration, and wikis for every project. Headquartered in California, it has been a subsidiary of Microsoft since 2018. It is commonly used to host open source software development projects. As of June 2022, GitHub reported having over 83 million developers and more than 200 million repositories, including at least 28 million public repositories. It is the largest source code host . History GitHub.com Development of the GitHub.com platform began on October 19, 2007. The site was launched in April 2008 by Tom Preston-Werner, Chris Wanstrath, P. J. Hyett and Scott Chacon after it had been made available for a few months prior as a beta release. GitHub has an annual keynote called GitHub Universe. Organizational ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Microsoft Windows
Windows is a group of several proprietary graphical operating system families developed and marketed by Microsoft. Each family caters to a certain sector of the computing industry. For example, Windows NT for consumers, Windows Server for servers, and Windows IoT for embedded systems. Defunct Windows families include Windows 9x, Windows Mobile, and Windows Phone. The first version of Windows was released on November 20, 1985, as a graphical operating system shell for MS-DOS in response to the growing interest in graphical user interfaces (GUIs). Windows is the most popular desktop operating system in the world, with 75% market share , according to StatCounter. However, Windows is not the most used operating system when including both mobile and desktop OSes, due to Android's massive growth. , the most recent version of Windows is Windows 11 for consumer PCs and tablets, Windows 11 Enterprise for corporations, and Windows Server 2022 for servers. Genealogy By marketing ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
OS/2
OS/2 (Operating System/2) is a series of computer operating systems, initially created by Microsoft and IBM under the leadership of IBM software designer Ed Iacobucci. As a result of a feud between the two companies over how to position OS/2 relative to Microsoft's new Windows 3.1 operating environment, the two companies severed the relationship in 1992 and OS/2 development fell to IBM exclusively. The name stands for "Operating System/2", because it was introduced as part of the same generation change release as IBM's " Personal System/2 (PS/2)" line of second-generation personal computers. The first version of OS/2 was released in December 1987 and newer versions were released until December 2001. OS/2 was intended as a protected-mode successor of PC DOS. Notably, basic system calls were modeled after MS-DOS calls; their names even started with "Dos" and it was possible to create "Family Mode" applications – text mode applications that could work on both systems. Be ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
MS-DOS
MS-DOS ( ; acronym for Microsoft Disk Operating System, also known as Microsoft DOS) is an operating system for x86-based personal computers mostly developed by Microsoft. Collectively, MS-DOS, its rebranding as IBM PC DOS, and a few operating systems attempting to be compatible with MS-DOS, are sometimes referred to as "DOS" (which is also the generic acronym for disk operating system). MS-DOS was the main operating system for IBM PC compatibles during the 1980s, from which point it was gradually superseded by operating systems offering a graphical user interface (GUI), in various generations of the graphical Microsoft Windows operating system. IBM licensed and re-released it in 1981 as PC DOS 1.0 for use in its PCs. Although MS-DOS and PC DOS were initially developed in parallel by Microsoft and IBM, the two products diverged after twelve years, in 1993, with recognizable differences in compatibility, syntax, and capabilities. Beginning in 1988 with DR-DO ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
GOTO
GoTo (goto, GOTO, GO TO or other case combinations, depending on the programming language) is a statement found in many computer programming languages. It performs a one-way transfer of control to another line of code; in contrast a function call normally returns control. The jumped-to locations are usually identified using labels, though some languages use line numbers. At the machine code level, a goto is a form of branch or jump statement, in some cases combined with a stack adjustment. Many languages support the goto statement, and many do not (see § language support). The structured program theorem proved that the goto statement is not necessary to write programs that can be expressed as flow charts; some combination of the three programming constructs of sequence, selection/choice, and repetition/iteration are sufficient for any computation that can be performed by a Turing machine, with the caveat that code duplication and additional variables may need to be introduce ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Program Loop
In computer science, control flow (or flow of control) is the order in which individual statements, instructions or function calls of an imperative program are executed or evaluated. The emphasis on explicit control flow distinguishes an ''imperative programming'' language from a ''declarative programming'' language. Within an imperative programming language, a ''control flow statement'' is a statement that results in a choice being made as to which of two or more paths to follow. For non-strict functional languages, functions and language constructs exist to achieve the same result, but they are usually not termed control flow statements. A set of statements is in turn generally structured as a block, which in addition to grouping, also defines a lexical scope. Interrupts and signals are low-level mechanisms that can alter the flow of control in a way similar to a subroutine, but usually occur as a response to some external stimulus or event (that can occur asynchronously), ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
While Loop
In most computer programming languages, a while loop is a control flow statement that allows code to be executed repeatedly based on a given Boolean condition. The ''while'' loop can be thought of as a repeating if statement. Overview The ''while'' construct consists of a block of code and a condition/expression. The condition/expression is evaluated, and if the condition/expression is ''true'', the code within all of their following in the block is executed. This repeats until the condition/expression becomes false. Because the ''while'' loop checks the condition/expression before the block is executed, the control structure is often also known as a pre-test loop. Compare this with the ''do while'' loop, which tests the condition/expression ''after'' the loop has executed. For example, in the C programming language (as well as Java, C#, Objective-C, and C++, which use the same syntax in this case), the code fragment int x = 0; while (x 0 loop Factorial := Fac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Record Management Services
Record Management Services (RMS) are procedures in the VMS, RSTS/E, RT-11 and RSX-11M operating systems that programs may call to process files and records within files. Its file formats and procedures are similar to of those in some IBM access methods for several of its mainframe computer A mainframe computer, informally called a mainframe or big iron, is a computer used primarily by large organizations for critical applications like bulk data processing for tasks such as censuses, industry and consumer statistics, enterpris ... operating systems and by other vendors for file and record management. VMS RMS is an integral part of the system software; its procedures run in executive mode. (RMS was not integrated into RT-11 and RSTS/E, but was available as a "layered product".) RMS supports four record access methods: * Sequential Access * Relative Record Number Access * Record File Address Access * Indexed Access RMS supports four record formats: * Fixed length * Varia ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Conditional (programming)
In computer science, conditionals (that is, conditional statements, conditional expressions and conditional constructs,) are programming language commands for handling decisions. Specifically, conditionals perform different computations or actions depending on whether a programmer-defined boolean ''condition'' evaluates to true or false. In terms of control flow, the decision is always achieved by selectively altering the control flow based on some condition (apart from the case of branch predication). Although dynamic dispatch is not usually classified as a conditional construct, it is another way to select between alternatives at runtime. Terminology In imperative programming languages, the term "conditional statement" is usually used, whereas in functional programming, the terms "conditional expression" or "conditional construct" are preferred, because these terms all have distinct meanings. If–then(–else) The if–then construct (sometimes called if–then–els ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Compiled Language
A compiled language is a programming language whose implementations are typically compilers (translators that generate machine code from source code), and not interpreters (step-by-step executors of source code, where no pre-runtime translation takes place). The term is somewhat vague. In principle, any language can be implemented with a compiler or with an interpreter. A combination of both solutions is also common: a compiler can translate the source code into some intermediate form (often called p-code or bytecode), which is then passed to an interpreter which executes it. Advantages and disadvantages Programs compiled into native code at compile time tend to be faster than those translated at runtime due to the translation process's overhead. Newer technologies such as just-in-time compilation, and general improvements in the translation process are starting to narrow this gap, though. Mixed solutions using bytecode tend toward intermediate efficiency. Low-level programming ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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