9/14/2010. Chapter 3: Software Overview. Types of Software. Functions of Operating Systems. Software classification

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1 Chapter 3: Software Overview Types of Software 3.1 History of Operating Systems 3.2 Operating System Architecture 3.5 Security Plus: Application Programs and Software Application software Performs specific tasks for users System software Provides infrastructure t for application software Consists of operating system and utility software Software classification Functions of Operating Systems Oversee operation of computer Store and retrieve files Schedule programs for execution Coordinate the execution of programs Coordinate peripheral devices

2 Evolution of Shared Computing Operating System Components Batch processing Interactive processing Requires real-time processing Time-sharing/Multitasking Implemented by Multiprogramming Multiprocessor machines Shell: Communicates with users Text based Graphical user interface (GUI) Kernel: Performs basic required functions File manager Device drivers Memory manager Scheduler and dispatcher The shell as an interface between users and the operating system File Manager Directory (or Folder): A user-created bundle of files and other directories (subdirectories) Directory Path: A sequence of directories within directories

3 Memory Manager Getting it Started (Bootstrapping) Allocates space in main memory May create the illusion that the machine has more memory than it actually does (virtual memory) byplayinga shell a game in which blocks of data (pages) are shifted back and forth between main memory and mass storage Bootstrap: Program in ROM (example of firmware) Run by the CPU when power is turned on Transfers operating system from mass storage to main memory Executes jump to operating system The booting process Application Software Software Package: An application that focuses on a particular subject, such as word processing, and is sold to businesses and the general public. Documentation: An instruction manual that accompanies software. Also, a technical, detailed written description of the specific facts of a program

4 Spreadsheet: A table of columns and rows used by people responsible for tracking revenues, expenses, profits, and losses. Word-processing (WP) Program: A program that allows the user to enter, change (edit), move, store, and print text information. Desktop Publishing (DTP) Program: A program that combines text and image-handling features with document-design capabilities. Graphics Presentation Program: A program that translates data into visual representations using charts, graphs, and map. Photo Editing Program: A program used to touch up, remove, or add features to a digital version of photographs. Illustration Program: A program in which the computer screen becomes a drawing board on which artists translate their ideas into visual form. Database: A collection of data and information describing items of interest to an organization. Database Management Program: A program that makes it possible for users to manage the data in ways that increase accessibility and productivity. Browser: Client computer program designed to locate and display information on the World Wide Web. Computer Programming Language: A series of commands or codes that a computer can translate into the electronic pulses that underlie all computing activities. Utility Program (Utilities): Special programs used to perform tasks that occur repeatedly using processing. Custom Software: Software written specially for a particular business. Security Software: Designed to protect computers against attacks, viruses, and other malicious behavior. 4

5 Software Trends Greater use of prewritten software packages. Greater user of prewritten components. Object-oriented Programming: Software development combining data and procedures into a single object. Object: A component that contains data about itself and how it is to be processed. Security Attacks from outside Problems Insecure passwords Sniffing software Counter measures Auditing software 3-18 Security (continued) Attacks from within Problem: Unruly processes Counter measures: Control process activities via privileged modes and privileged instructions