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 3rd 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 3rd party vendors = Norton, McAfee, AVG