A+ Guide to Managing and Maintaining Your PCFifth Edition

Chapter 2

How Hardware and Software Work Together

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You Will Learn…

About operating systems, what they are, and what they do

How an OS interfaces with users, applications, and hardware

How system resources help hardware and software communicate

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Introducing Operating Systems

Software that controls a computer

Acts as a middleman between applications and hardware

Two main internal components

Shell

Kernel

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OS as a Middleman

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The Shell and the Kernel

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Common Operating Systems

DOS Windows 9x Windows NT, Windows 2000, and

Windows XP Unix Linux OS/2 Mac OS

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What an Operating System Does Provides user interface

Stores, retrieves, and manipulates files and folders

Manages applications

Manages hardware

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How an OS Provides a User Interface Command-driven interfaces

Menu-driven interfaces

Icon-driven interfaces

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A Menu-Driven Interface

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How an OS Manages Files and Folders Uses file system (FAT or NTFS) to track how

clusters are used for each stored file

Uses directories, subdirectories, and files

Uses partitions and logical drives on hard drive

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Tracks, Sectors, and Clusters

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Files and Directories

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Partitions and Logical Drives

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How an OS Manages Applications

Provides access to hardware resources

Manages data in memory and in secondary storage

Performs other background tasks

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Loading Application Software Using the Windows Desktop

Shortcut icon

Start menu

Run command

Windows Explorer or My Computer

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Using a Shortcut Icon to Load Software

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Real and Protected Operating Modes Real (16-bit) operating mode

CPU processes 16 bits of data at one time Software has “real” access to hardware

Protected (32-bit) operating mode CPU processes 32 bits of data at one time More than one program can be running, each one

“protected” from others Uses preemptive multitasking

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16-Bit and 32-Bit Software

16-bit software

Written for Windows 3.x

Accesses data 16 bits at a time

Programs should not infringe on resources of other programs that are running

32-bit software

Written for Windows 95 and later Windows OSs

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How an OS Manages Hardware

Uses device drivers or the BIOS (system BIOS, startup BIOS, or CMOS setup) to interface with hardware

Trend is to manage devices with device drivers rather than BIOS

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How an OS Manages Hardware (continued)

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How an OS Uses Device Drivers to Manage Hardware Device drivers provide OS with software

necessary to control devices

16-bit read-mode drivers

Supported by Windows 95/98

32-bit protected-mode drivers

Supported by Windows 95/98, Windows Me, and Windows NT/2000/XP

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How an OS Uses System BIOS to Manage Devices

To communicate with simple devices (eg, floppy drives or keyboards)

To access the hard drive

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Using System BIOS

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Using System BIOS (continued)

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System Resources

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System Resources (continued)

Depend on certain lines on a bus on motherboard

System bus components Data bus carries data

Address bus communicates addresses (memory addresses and I/O addresses)

Control bus controls communication (IRQs and DMA channels)

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System Bus Components

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Interrupt Request Number (IRQ)

Line on a bus that device needing service uses to alert the CPU

Managed by interrupt controller on motherboard Early motherboards: eight IRQs

Second group of IRQs and second interrupt controller have been added to accommodate need for more devices

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Common Assignments for First Eight IRQs

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Second IRQ Controller

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Viewing IRQ Assignments

Microsoft Diagnostic Utility (MSD) for DOS

Device Manager for Windows 2000/XP and Windows 9x

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Viewing IRQ Assignments (continued)

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Viewing IRQ Assignments (continued)

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Memory Addresses

Hexadecimal numbers assigned to RAM and ROM so the CPU can access both

Used to access physical memory

Often written in segment:offset form(eg, C800:5)

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Memory Addresses (continued)

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I/O Addresses

Numbers CPU can use to access hardware devices

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I/O Addresses (continued)

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Common Assignments for I/O Addresses

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Direct Memory Access (DMA) Channels

Shortcut method that lets an I/O device send data directly to memory, bypassing the CPU

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DMA Channels

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OS Tools to Examine a System

Device Manager

System Information utility

Microsoft Diagnostic Utility (MSD)

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Device Manager

Primary tool used to manage hardware devices under Windows 2000/XP and Windows 9x

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Device Manager ( continued)

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System Information Utility

Gives similar, but more, information than Device Manager

BIOS version in use

Directory where OS is installed

How system resources are used

Information about drivers and their status

Additional information about software

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Using Windows System Information

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Microsoft Diagnostic Utility (MSD) Useful for viewing information about the

system, including:

Memory

Video

Ports

Device drivers

System resources

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Using MSD

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Summary How hardware and software work together

Different operating systems

What they do

How they work to control hardware devices

How an OS provides the interface that users and applications need to command and use hardware devices