Transcript A+ Guide to Managing and Maintaining Your PC, 5e

A+ Guide to Managing
and Maintaining Your PC
Fifth Edition
Chapter 2
How Hardware and Software
Work Together
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
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Software that controls a computer
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Acts as a middleman between applications and
hardware

Two main internal components

Shell (User Interface)

Kernel (Central Module)
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Introducing Operating Systems
(continued)

Shell

The outermost layer of a program. Shell is another
term for user interface. Operating systems and
applications sometimes provide an alternative shell
to make interaction with the program easier.

For example, if the application is usually command
driven, the shell might be a menu-driven system
that translates the user's selections into the
appropriate commands.
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Introducing Operating Systems
(continued)

Kernel

The central module of an operating system. It is the part of
the operating system that loads first, and it remains in main
memory. Because it stays in memory, it is important for the
kernel to be as small as possible while still providing all the
essential services required by other parts of the operating
system and applications.

Typically, the kernel is responsible for memory
management, process and task management, and disk
management.
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OS as a Middleman
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The Shell and the Kernel
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Common Operating Systems
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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
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Programs and operating systems that accept commands in the form of
special words or letters. More flexible than menu & icon driven
interfaces
Programs that allow you to choose from a list of options in a menu
Icon-driven interfaces

Programs and operating systems that accept commands in the form of
icons.
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A Command-Driven Interface
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A Menu-Driven Interface
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An Icon-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
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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
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Provides access to hardware resources
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Manages data in memory and in secondary
storage
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Performs other background tasks
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Loading Application Software
Using the Windows Desktop

Shortcut icon
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Start menu
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Run command
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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
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Real (16-bit) operating mode
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CPU processes 16 bits of data at one time
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Software has “real” access to hardware
Protected (32-bit) operating mode

CPU processes 32 bits of data at one time
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More than one program can be running, each one
“protected” from others
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Uses preemptive multitasking
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16-Bit and 32-Bit Software
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16-bit software
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Written for Windows 3.x
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Accesses data 16 bits at a time
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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
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Uses device drivers or the BIOS (system
BIOS, startup BIOS, or CMOS setup) to
interface with hardware
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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
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Device drivers provide OS with software
necessary to control devices
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16-bit read-mode drivers
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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
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To communicate with simple devices (eg,
floppy drives or keyboards)
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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
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System bus components
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Data bus carries data
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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)
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Line on a bus that device needing service uses
to alert the CPU
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Managed by interrupt controller on
motherboard
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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
Start -> All programs -> Accessories -> System tools -> System information -> IRQs
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Second IRQ Controller
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Viewing IRQ Assignments
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Microsoft Diagnostic Utility (MSD) for DOS
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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)
Refer pg 41 of A+ (M.Pastore)
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Memory Addresses
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Hexadecimal numbers assigned to RAM and
ROM so the CPU can access both
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Used to access physical memory
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Often written in segment:offset form
(eg, C800:5)
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Memory Addresses (continued)
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I/O Addresses
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Numbers CPU can use to access hardware devices
Common I/O addresses to know for A+ exam
170h-17Fh Secondary IDE controller, master drive
1F0h-1FFh Primary IDE controller, master drive
278h-27Fh LPT 2
2F8h-2FFh COM 2
378h-37Fh LPT 1
3F8h-3FFh COM 1
PS: Note that the h at the end of the number denotes hexadecimal number
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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
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Device Manager
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System Information utility
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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
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Gives similar, but more, information than
Device Manager
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BIOS version in use
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Directory where OS is installed
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How system resources are used

Information about drivers and their status

Additional information about software
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Using Windows System
Information
Click Run and type msinfo32 to activate the System Info
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Microsoft Diagnostic Utility
(MSD)
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Useful for viewing information about the
system, including:

Memory
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Video
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Ports

Device drivers

System resources
PS: MSD is not supported in Win NT, Win XP & Win 2000. Use System Information
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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
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