ch04 - CHAPTER 4 SYSTEM SOFTWARE Without software-the set...

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1 CHAPTER 4 SYSTEM SOFTWARE Without software-the set of instructions that tells the computer what to do- a computer is just an expensive collection of wires and components . System software includes all of the programs needed to keep a computer and its peripheral devices running smoothly. System software has two major components: (1) the operating system and (2) system utilities, which provide various maintenance functions. Operating System The operating system (OS) is essentially a set of programs designed to work with a specific type of hardware, such as a PC or a Macintosh. Its most important role lies in coordinating the various functions of the computer’s hardware. The operating system also provides support for running application software. The operating system is most often found on a hard disk, although on some small handheld computers you’ll find the operating system on a memory chip. 9 The functions of the operating system are: ¾ Starting the computer ¾ Managing programs ¾ Managing memory ¾ Handling messages from input and output devices ¾ Enabling user interaction with the computer An operating system works at the intersection of application software, the user, and the computer’s hardware. It manages programs, parcels out memory to applications, deals with internal messages from input and output devices, and provides a means of communicating with the user. An important operating system function—and the one that most dramatically affects an operating system’s overall quality—is the way it runs and manages programs. In the early days of personal computing, single- tasking operating systems could run only one application program at a time. Today, many users work with five or more applications simultaneously. Multitasking operating systems enable a user to work with two or more programs at the same time. Memory is managed by the computer’s operating system. The operating system gives each running program its own portion of memory and attempts to keep the programs from interfering with each other’s use of memory. Most of today’s operating systems can make the computer’s main memory (RAM) seem larger than it really is. This trick is accomplished by means of virtual memory , a method of using the computer’s hard disk as an extension of RAM. Most operating systems come with drivers for popular input and output devices. Drivers are programs that contain specific information about a particular brand and model of input or output device. They enable communication between the operating system and the input and output components of a computer system. From the user’s perspective, the most important piece that an operating system provides is the user interface , the part of the operating system that the user sees and interacts with and by which users and programs communicate with each other. User interfaces typically enable the user to do the following: start (launch) application programs, manage disks and files, and shut down the computer safely
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