Chapter 2 – Software Part A

Definition Computer is made up of two components Hardware Physical components Software Instructions for the computer Two main categories  System software = makes the computer run  Application software = use computer to perform specific processing tasks for user

Copyright Law Majority of software falls under protection of copyright law. Owner Use with restriction Illegal to copy without permission Commercial software “Pay before you use” Shareware “Try before you buy” Limited usage or limited version Freeware Copyrighted and free Public domain Not copyrighted Can be used without restriction

Software code Most software packages consist only of executable code Readable only by computer Protects code from being altered or copied Source code Code written by software developers Compiler translates to executable code Open Source code Software package includes source code Can be reviewed and modified Small, growing trend

System requirements Minimum hardware components needed to successful install and run software. Processor speed Amount of memory Required hard disk space Other requirements = video, CD-ROM speed Application software written for platform Combination of processor and operating system

System software Operating system Most important piece of software Controls computer “nucleus of all software activity” Consists of multiple programs System utilities Help maintain the computer

OS Kernel Core element Memory-resident Loaded at startup Resides in memory until PC powered off Responsible for loading all other software User interface = allows user to enter commands Command-driven User types in text commands Oldest interface Graphical User interface (GUI = “gooey”) User uses point-and-draw device (mouse) to choose from a menu of commands or icons (graphic images)

OS (contd) Drivers Software programs that allow OS to control hardware components Supplied by hardware vendor Multi-tasking = concurrent execution of more than 1 program at a time Processor can only execute 1 command at a time OS rotates “time slices’ between multiple programs Appears to be running simultaneously (but NOT!)

OS (contd) Multiprocessing Supports multiple processors Allows simultaneous execution of instructions Windows XP Pro supports 2 processors OS supports single computer and user NOS = network OS supports multiple computer and users

OS varieties Microsoft Windows Most popular Intel-compatible processor Many versions Legacy = (95, 98, ME, NT and 2000) Current = XP and Server 2003 (NOS) Apple MAC OS X Motorola platform 10% market share

OS varieties (contd) Linux Growing in popularity Open Source freeware Customizable

System Utilities Most used system utilities File management File and disk maintenance Security Screen savers Backup Can exist as part of OS Available through 3 rd party vendor ie Norton Utilities

Examples File management Windows Explorer or My Computer Folders organize files Copy, move, delete and add files and folders File maintenance Disk Defragmenter (Start > All Programs > Accessories > System Tools) Locates and consolidates fragmented files to improve file access time

Examples Security – antivirus, spy ware, ad ware, firewall, pop-up blocker 3 rd party vendors = Norton, McAfee, AVG