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College of Information Technology / Software Department ………………………………………………….. Computer Skills II / First Class / Second Semester LEC. 12 Programs, Applications, and software Software Software is a general term for the various kinds of programs used to operate computers and related devices. Software is any set of machine-readable instructions that directs a computer's processor to perform specific operations. Computer software contrasts with computer hardware, which is the physical component of computers. Computer hardware and software require each other and neither can be realistically used without the other. Software provides instructions that tell the hardware what to do, both software and hardware work together to perform the tasks requsted by the user. There are two major types of software, namely system software and application software, system software manages and integrates a computer's capabilities but does not directly perform tasks that benefit the user, system software includes operating systems and any program that supports application software, application software includes programs that users are directly interested in. Software Application Software System Software OSs sucha s Wndows, MacOS, Linux, etc. tell the computer how to interpret commands, mnage files, process input and output, etc. Once the OS is running, software can be installed and various programs can be run to enable the user to perform specific types of tasks with the computer. OS must be present before any other software, such as a word processor, can run. Software is essentially a program which is a set of coded instructions that a computer can understand to solve a problem or produce a desired result. Two basic types of computer programs are (1) an operating system, which provides the most fundamental instructions a computer uses in its operations, and (2) an application software , which runs on 61 the operating system and does a specific job such as word processing. Application software cannot run on itself but is dependent on system software to execute. An operating system is like the software administrator of the computer, managing interactions between hardware and applications. It’s one type of system software, which is the software that the system uses the user doesn’t interact with it directly. When you buy software, you normally buy an executable version of a program. This means that the program is already in machine language, it has already been compiled and assembled and is ready to execute. Some general kinds of application software include: - Productivity software, which includes word processors, spreadsheets, and tools for use by most computer users - Presentation software - Graphics software for graphic designers - CAD/CAM software - Specialized scientific applications program A program usually requires an installer and will install various files needed on the computer for it to work. A program will include and require an uninstaller in order to get deleting the various files installed all over your hard disk. In a computing context, software and program are mostly synonymous. Software can be made up of more than one program, however, and if you’re talking about a product, it’s usually called software. Programs consist of an organized list of instructions that written to perform a specified task on a computer, when executed, causes the computer to behave in a predetermined manner. A program contains a list of items (called variables) and a list of directions ( توجيهاتcalled statements) that tell the computer what to do with the variables. The variables can represent numeric data, text, or graphical images, etc. 62 There are many programming languages C, C++, Pascal, VBASIC,FORTRAN, COBOL, LISP , Java, C#, etc., these are all high-level languages. One can also write programs in low-level languages called assembly languages, although this is more difficult. Lowlevel languages are closer to the language used by a computer, while high-level languages are closer to human languages. Typically, the program is put into a storage area (memory) accessible to the computer, the computer gets one instruction and performs it and then gets the next instruction, the memory can also contain the data that the instruction operates on, the program's instructions are executed in a central processor. The program has an executable form that the computer can use directly to execute the instructions. Source code may be converted into an executable file (sometimes called an executable program or a binary) by a compiler and later executed by a central processing unit. Alternatively, computer programs may be executed with the aid of an interpreter, eventually أخيرا, every program must be translated into a machine language that the computer can understand. This translation is performed by compilers, interpreters, and assemblers. The instructions, which we will call statements, look different in different programming languages, but there are a few basic operations most languages perform: input: Get data from the keyboard, or a file, or some other device. output: Display data on the screen or send data to a file or other device. math: Perform basic mathematical operations like addition and multiplication. testing: Check for certain conditions and run the appropriate sequence of statements. repetition: Perform some action repeatedly, usually with some variation. Every program you've ever used, no matter how complicated, is made up of statements that perform these operations. Thus, one way to describe programming is the process of breaking a large, complex task up into smaller and smaller subtasks until the subtasks are simple enough to be performed with one of these basic operations. 63 Programming errors are called bugs and the process of tracking them down and correcting them is called debugging. Application An app will usually be (or at least feel like) one file downloaded, it will have one icon. An application (the short form of application program) is software that performs a specific function directly for the user, allows you to perform specific tasks, or in some cases, for another application program. An application is a program, or group of programs, that is designed for the end user. Applications for desktop or laptop computers are sometimes called desktop applications, and those for mobile devices are called mobile apps. When you open an application, it runs inside the operating system until you close it. Most of the time, you will have more than one application open at the same time, and this is known as multitasking. An application is a program that interacts with a human directly. For example, the driver for your video card is a program (or probably a set of programs) but it is not an application, your operating system is a program, but it is not an application, your browser is an application. Examples of applications include word processors, database programs, Web browsers, development tools, drawing, paint, image editing programs, and communication programs. Applications use the services of the computer's operating system and other supporting applications. 64 65