Technology In Action

Technology In Action

Technology In Action Chapter 5 Using System Software: The Operating System, Utility Programs, and File Management

Topics • System software • Operating systems: • Kinds of systems • Common desktop systems • User interaction • Manage the processor • Manage memory

Topics • Operating systems: • Manage hardware • Interact with application software • Start the computer • Keep the computer organized • Desktop and windows features • Utility programs

Operating systems Control computer functions: Hardware Memory Application programs System maintenance Provide user interface System utilities Programs that perform computer housekeeping tasks: Manage system resources Improve efficiency Virus prevention System Software

System Software • The set of software programs that helps run the computer and coordinates instructions between application software and the computer’s hardware devices

System Software • Consists of two primary types of programs • Operating system (OS) • The main program that controls how your computer system functions • The OS manages the computer’s hardware, the processor (CPU), memory, storage devices, and peripheral devices • Provide a consistent means for software applications to work with the CPU

System Software • Consists of two primary types of programs • Operating system (OS) • Responsible the management , scheduling, and interaction of tasks as well as system maintenance

System Software • Consists of two primary types of programs • Utility Programs • Small programs that perform many of the general housekeeping tasks for the computer, such as system maintenance and file compression

Operating System Categories • Every computer has an operating system • The computer cannot operate without it • Four categories: • Real-Time (RTOS) • Single-User, Single-Task • Single-User, Multitask • Multiuser

Real-Time Operating Systems • Machinery that is required to perform series of specific tasks in an exact amount of time require a RTOS • Systems with a specific purpose and a certain result

Real-Time Operating Systems • An OS with a specific purpose and guarantees certain response times for particular computing tasks • Uses include: • Industrial machines • Robotic equipment • Automobiles • Video game consoles • Home appliances

Single-task systems Perform one task at a time PDAs: Pocket PC Palm OS Windows Mobile MS-DOS Multitask systems Perform simultaneous tasks Windows MAC OS Linux Single-User Operating Systems

Multiuser Operating Systems • Known as network operating systems • Allow access to the computer system by more than one user • Manage user requests • Systems include: • UNIX • Novell Netware • Windows Server 2003

Desktop Operating Systems • Operating system combined with the processor is known as a platform • Microsoft Windows / Intel • Apple Macintosh / Motorola • Desktop operating systems include: • Microsoft Windows • MAC OS • UNIX • Linux

Introduces point-and-click commands with a mouse and includes modest multitasking capabilities and desktop applications. First widely used PC graphical user interface (GUI) operating system. Improved point-and-click mouse operations and multitasking capabilities. Fundamentally different operating system with increased security, power, performance, and multitasking scheduler. This upgrade to Windows 95 and Windows 98 includes system backup and multimedia capabilities (such as Media Player). This operating system runs faster and more efficiently, introduces Plug and Play capabilities, long file names, short-cut right-click menus, and a cleaner desktop. Includes better graphics capabilities and introduces keyboard shortcuts and the ability to overlap windows. This upgrade to Windows NT offers improvements to file security and Internet support. This upgrade includes additional file protection and incorporates Internet Explorer 4.0, a customizable taskbar, and desktop features Offers a new multi-user desktop as well as improved digital media features and Internet capabilities. Windows 2000 (2000) Windows ME (2000) Windows XP (2001) Windows 98 (1998) Windows 95 (1995) Windows NT (1993) Windows 3.x (1990-1992) Windows 1.0 (1985) Windows 2.0 (1987) Microsoft Windows • Market leader – 90% market share Click to view the various Windows systems

Windows Vista • New OS to be introduced in 2007

MAC OS • First operating system with point-and-click technology (Graphical User Interface) • Excellent in: • Graphics display • Processing capabilities • System reliability • Document recovery • Fewer software applications MAC OS X

UNIX • Multiuser, multitask operating system • Used primarily with mainframes as a Network OperatingSystem • Also used on PCs

UNIX • Originally conceived in 1969 at Bell Labs • Individual vendors modify the UNIX code to run specifically on their hardware

Linux • Open-source operating system that is freely available for developers to use or modify as they wish • Based on UNIX • Stable system that is not subject to crashesand failures • Free • May be downloaded through the Internet

What the Operating System Does • Provides a way for the user to interact with the computer • Manages the CPU • Manages memory andstorage • Manages the system’shardware and peripheral devices • Coordinates application software with the CPU

The User Interface • Enables you to interact with the computer • Types of interfaces: • Command-driven interface • Menu-driven interface • Graphical user interface Command-driven Menu-driven Graphical

The User Interface • Command-driven Interface • The user had to type very specific commands to get the computer to perform a function • Menu-driven Interface • You choose a command from menus displayed on the screen • Eliminated the need to know every command

The User Interface • Graphical User Interface (GUI) • GUIs display graphics and use the point-and-click technology of the mouse and cursor, making them much more user-friendly • GUIs use • Windows – rectangular boxes that contain programs displayed on the screen • Menus- lists of commands that appear on the screen • Icons – pictures that represent an object such as a software application or a file or folder

The User Interface • Graphical User Interface • Unlike Windows or MAC OS, Linux does not have a single, default GUI interface • Users are free to choose among many commercially available or free interfaces

Processor Management • When you use your computer, you are usually asking it to perform several tasks at once • Printing a document • Waiting for a file to download from the Internet • Listening to a CD from your CD drive • Working on a Powerpoint presentationall at the same time or what appears to be the same time Operating System Process 3rd Process 1st Process 4th Process 2nd REQUEST

Processor Management • The Processor needs the operating system to arrange for the execution of all these activities in a systematic way to give the appearance that everything is happening simultaneously Operating System Process 3rd Process 1st Process 4th Process 2nd REQUEST

Processor Management • To do so, the operating system assigns a slice of its time to each activity requiring the processor’s attention • The OS must then switch between different processes thousands of times a second to make it appear that everything is happening seamlessly • Multitasking Process 3rd Process 1st Process 4th Process 2nd

Processor Management • When you tell your computer to print a document, the printer generates a unique signal (interrupt) to inform the operating system. • Every device has its own unique interrupt which is associated with an interrupt handler • A special numerical code that prioritizes the requests Process 3rd Process 1st Process 4th Process 2nd

Processor Management • These requests are placed in the Interrupt Table in the computer’s primary memory (RAM) • The OS processes the task assigned a higher priority before processing a task with a lower priority • Preemptive multitasking Process 3rd Process 1st Process 4th Process 2nd

Processor Management • In our example • When the OS receives the interrupt from the printer, it pauses the CPU from its typing activity and from the CD activity and puts a “memo” in a special location in RAM • Stack • The memo is a reminder of where the CPU was before it left off so that it can work on the printer request Process 3rd Process 1st Process 4th Process 2nd

Processor Management • In our example • The CPU then retrieves the printer request from the Interrupt Table and begins to process it • On completion of the printer request, the CPU goes back to the stack, retrieves the memo and returns to that activity until it is interrupted again Process 3rd Process 1st Process 4th Process 2nd

Memory Management • The operating system allocates space in RAM for instructions and data RAM Operating System

Memory Management • The OS is responsible for coordinating the space allocations in RAM to ensure that there is enough space for all the waiting instructions and data • It then clears the items from RAM when the processor no longer needs them • When there isn’t enough room in RAM for the OS to store the required data and instructions, the OS borrows room from the hard drive

Virtual Memory • The process of optimizing RAM storage by borrowing hard drive space FULL Operating System

Virtual Memory • When more RAM is needed The OS is responsible for coordinating , the OS swaps out from RAM the data or instructions that have not been recently used and moves them to a temporary storage area on the hard drive • Swap File

Virtual Memory • If the data or instructions in the Swap File are needed later, the OS swaps them back into active RAM and replaces them in the hard drive’s Swap File with less active data or instructions • Paging

Virtual Memory • As your data and instructions get bigger and bigger, the more space you will need on your hard drive • Eventually your computer will become sluggish and slower as it is forced to page more and more often • Thrashing

Virtual Memory • The solution to thrashing is to increase the amount of RAM in your system so that it will not be necessary for it to send data and instructions to virtual memory

Hardware Management • Each device attached to your computer comes with a special program • Device Driver • Facilitates the communication between the hardware device and the OS • Translates the specialized commands of the device to commands that the OS can understand, and vice versa • Devices will not function without the proper device drive because the OS would not know how to communicate with them

Hardware Management • Today most devices come with the driver already installed in Windows • Plug and Play • A software and hardware standard that Microsoft created with Windows 95 • Designed to facilitate the installation of a new piece of hardware in PCs by including the driver the device needs to run into the OS • Because the OS includes this software, incorporating a new device seems automatic

Hardware Management • When you install a non-Plug and Play device, you will be prompted to insert the media that was provided with the device for the OS to obtain the driver

Hardware Management • Device drivers: • Programs that enable the operating system to communicate with peripheral devices • Provided by the manufacturer of the device • Plug and Play: • Hardware and software standard • Facilitates the installation of new hardware

Software Application Coordination • Software applications feed the CPU the instructions it needs to process data • Programs • For programs to work with the CPU, they must contain code that the CPU recognizes

Software Application Coordination • Rather than having the same blocks of code for similar procedures in each software application, The OS includes the blocks of code that software applications need to interact with it • Application programming interfaces (APIs) • Not only do APIs avoid redundancies in software code, they also make it easier for software developers to respond to changes in the OS

Software Application Coordination • To create programs that can communicate with the OS. Software programmers need only refer to the API code blocks in their individual application programs, rather then including the entire code in the application itself • Not only do APIs avoid redundancies in software code, they also make it easier for software developers to respond to changes in the OS

Boot Process • Steps Involved in the Boot Process • The basic input/output system (BIOS) is activated • A program that manages the data between the OS and all the input and output devices attached to the system • Responsible for loading the OS from its permanent location on the hard drive into memory

Boot Process • Steps Involved in the Boot Process • Perform the Power-on Self Test (POST) • Ensures that the peripheral devices are attached and operational • The BIOS compares the results of the POST with the various hardware configurations that are permanently stored in CMOS • Complimentary Metal-Oxide Semiconductor

Boot Process • Steps Involved in the Boot Process • Load the Operating System • BIOS locates the System Files • The OS supervisor is loaded from its permanent storage location on the hard drive to RAM • Memory Resident • Other parts of the OS that are less critical are loaded into RAM on an as-needed basis • Nonresident

Technology In Action