Operating Systems: Software in the Background Chapter 2 Operating Systems: Software in the Background

Types of Software Systems software Application software programs related to coordinating computer operations includes operating systems, language translators, and utility programs Application software software designed to accomplish a specific task includes word processors, electronic spreadsheets, etc.

What is an operating system? The OS is a set of programs that controls access to the hardware and software resources of the computer. kernel - the part of the OS that supervises the overall operation of the OS resident when computer is on (stored in main memory)

Booting the system When the computer it turned on, the resident portions of the OS must be loaded into main memory from the hard disk. A small program in ROM makes internal hardware checks then starts the booting process.

Popular operating systems PC’s MS Windows Mac OS Linux - Unix-like system for PC’s Multiuser systems Unix - not tied to a specific platform, primary OS for the Internet

Terms platform - combination of hardware and OS used by a computer software is designed for a specific platform prompt - a signal displayed on screen to indicate that the system is waiting for a command or input icon - a picture that represents a program, hardware device, or data object (file)

More terms menu - a list of options from which a command can be selected operating environment (shell) - a program that overlays a program (often an OS) to provide a more user friendly interface

Operating System Functions Management of the computer’s hardware resources multiprogramming - single CPU runs two or more programs concurrently time sharing - special form of multiprogramming in which each user is allotted a time slice multiprocessing - multiple CPUs run programs simultaneously virtual memory - currently active part of program in memory, the rest on disk, swapped in and out as needed

Operating System Functions Execution and provision of services for application software providing access to peripherals spooling - print jobs are written temporarily to disk until the printer is ready retrieval of files for use allocating space for and storing files

Operating System Functions Establishment of a user interface - the way a user communicates with a program 2 major types for operating systems command line interface text-based, older, harder to learn MS-DOS, Unix, Linux graphical user interface use icons and menus to allow command input, popular interface for PC’s, easy to learn Windows, Mac OS

Utility programs some may be included with the OS file manager - organizes files for easy access provides the ability to display, copy, name, delete, and move files format and copy disks backup and restore duplication of important materials for safe storage

More utility programs disk defragmentation file compression reorganization of files on disk to improve system performance file compression programs to reduce the size of files for storage or transmission purposes device driver program that makes it possible for the OS to communicate with peripheral devices