1 chapter overview operating system basics the command prompt and dos mode operations file systems

1

Chapter Overview

Operating System Basics The Command Prompt and DOS Mode

Operations File Systems

2

The Software Core

3

A Short History of MS-DOS

4

Understanding DOS

All versions were built for a specific class of CPU.

MS-DOS never overcame critical limitations.

All versions used a command-line interface.

You must use the DOS prompt to set up a new system or hard disk drive.

5

DOS Boot Sequence and Files

Three core programs IO.SYS MSDOS.SYS COMMAND.COM

Two optional startup files CONFIG.SYS AUTOEXEC.BAT

6

Summary of Steps in Booting the System 1. The power-on self test (POST) runs and

invokes the operating system (OS).2. The read-only memory basic input/output

system (ROM BIOS) looks for an OS and checks for IO.SYS and MSDOS.SYS.

3. The OS processes CONFIG.SYS, if present.4. COMMAND.COM is loaded.5. The OS processes AUTOEXEC.BAT, if present.6. COMMAND.COM presents the active-drive

prompt.

7

The DOS File System The file is the primary unit of data storage. Files are organized into directories. File and directory names can be up to

eight characters long, followed by a period and a three-character extension.

Some universal extensions are .exe, .com, .sys, .bat, .txt, .doc, and .drv.

File and directory names are not case-sensitive.

8

The Evolution of Microsoft Windows Early versions presented a graphical

user interface (GUI) for MS-DOS. Microsoft Windows 3.11 was the last 16-

bit OS and the most well known version. Microsoft Windows 95 was the first 32-

bit version. All applications designed for Windows

have standard interfaces. Multitasking allows users to have more

than one application open.

9

Operating Modes Real mode could address only 1 MB of

random access memory (RAM). Standard mode allowed programs to run

in protected mode. In protected mode, programs could

address up to 16 MB of RAM. 386 enhanced mode could address up

to 4 GB of RAM. Certain applications included a Windows

runtime version.

10

Windows Resource Management

11

Memory Paging and Virtual Machines

Virtual memory is an area on the hard disk drive (called a swap file) that the system uses to store program code temporarily.

Virtual machines (VMs) allow multiple programs to operate.

DOS programs run individually in separate VMs.

12

Windows Operating Systems Microsoft Windows for Workgroups 3.11 is an

upgrade to Microsoft Windows 3.1. Windows 95, Microsoft Windows 98, and

Microsoft Windows Me can be networked easily.

Microsoft Windows NT is designed for networking.

Microsoft Windows 2000 replaces Windows NT. Upgrading to Windows NT or Windows 2000

could present compatibility problems with some hardware and applications.

13

The COMMAND Command

MS-DOS uses a text-based command-line user interface.

A text-based interface requires no drivers because display functions are built in.

COMMAND.COM provides the user interface.

14

Working with the Prompt

Typing PROMPT /? or HELP PROMPT provides help information.

DOS HELP returns information on customizing the prompt and the information that appears.

15

Internal and External Commands

External commands exist as separate files.

Windows has its own set of system utilities.

Internal commands are contained within COMMAND.COM.

Command mode requires typing a command instead of clicking an icon.

16

DOS Mode Navigation and File Management

The DOS file system uses a tree structure. A fully qualified path is the list of

directories from the root to the file. The DIR command displays the contents of

the current or a specified directory. DOS does not support Windows long

filenames. The MD command creates a new directory.

17

The PATH Command

PATH allows you to display and change the search path.

%PATH% appends the old path to the new path.

Programs in path directories can be run from any location on the computer.

18

Creating a Batch File

A batch file is an executable file that runs a series of existing commands or applications.

Commands listed in the file are executed in sequence.

Any executable that can be run from the prompt can be included in a batch file.

19

Renaming a File

The RENAME or REN command allows you to rename a file.

The CD command allows you to change directories.

The CLS command clears the screen.

20

Using Edit

21

Summary of DOS Terminology

22

CONFIG.SYS Commands

BUFFERS

COUNTRY

DEVICE

DEVICEHIGH

DOS

FCBS

FILES

INSTALL

LASTDRIVE

MOUSE.SYS

NUMLOCK

SHELL

SWITCHES

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AUTOEXEC.BAT Commands

DOSKEY

ECHO

KEYB

MOUSE.EXE

PATH

PAUSE

PROMPT

SET

SHARE

SMARTDRV

24

File System Basics

The file system organizes data on the storage medium.

Different media require different file systems.

File systems define naming conventions, file size, and media capacity.

Magnetic media employ several different file systems, depending on the OS.

25

Key File System Terms

Block Boot disk Boot sector Cluster Dual boot Encryption

End-of-file (EOF) marker

File File

allocation table (FAT)

File format File handle File locking

Filename Folder Format Low-level

format Master

boot record

Partition table

Primary partition

Sector Track Volume

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Comparing and Choosing File Systems

Decision factors: Dual boot requirement Number and size of hard disk drives Size of partitions Need to support legacy applications Need for advanced features such as security

27

FAT-Based File Systems

All modern PCs can use FAT. FAT organizes files by listing them in a

table. Two copies of the table are maintained

on the media. FAT was developed for and is still used

by floppy disk drives. There are three versions: FAT12, FAT16,

and FAT32.

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FAT16 and FAT32 Compared and Contrasted

High compatibility Use of MS-DOS bootable

floppy disk Performance advantage on

small volumes Manual intervention to use

FAT copy No backup of boot sector 2-GB volume limit Better performance when

operating in real mode or safe mode

Dual boot with Windows NT and Windows 98

8.3 filenaming limit

Limited compatibility No use of MS-DOS bootable

floppy disk More efficient allocation of

disk space Automatic use of FAT copy if

needed Automatic backup of boot

sector Support of 32-GB volumes Faster load times for

applications and large data files

No dual boot with Windows NT and Windows 98

Support of filenames up to 255 characters

FAT16 FAT32

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The NT File System (NTFS)

Was introduced with Windows NT Supports long filenames and is

optimized for multiuser environments Provides file and folder level security Is more reliable than previous file

systems Is not completely supported under

Windows NT

30

Advantages and Disadvantages of NTFS

Advantages Disadvantages

Supports volumes up to 2 terabytes (TB)

Maintains a recovery log Has no limit on number of

entries at root Allows faster file access Supports disk quotas

(Windows 2000) Supports file and folder

compression Supports file and folder

security

Does not allow accessing NTFS volumes under MS-DOS, Windows 95, or Windows 98

Does not allow using NTFS volumes as a primary partition for dual booting MS-DOS, Windows 95, or Windows 98

Could decrease performance on volumes smaller than 400 MB

31

File System Size Limitations

Different OSs handle cluster size differently.

Under FAT volumes, drives smaller than 16 MB are formatted as FAT12.

MS-DOS, Windows 95, and Windows 98 cannot access FAT16 volumes larger than 2 GB.

32

File System Security FAT attributes on FAT file systems

FAT has attributes that can protect files from being overwritten or viewed.

Attributes can be set by using the ATTRIB DOS-mode command, or by right-clicking a file in Windows and selecting the Properties option.

NTFS file and folder security NTFS uses permissions to determine who can

access the file or folder. Permissions are set by using the Security tab

for the file or folder.

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Chapter Summary An OS is the interface between the hardware and the

user. All OSs have a user interface, memory, and file

management. Technicians need to know how to perform command

prompt operations. Technicians who work with older OSs must

understand MS-DOS and DOS startup files. Internal and external commands can be used to

configure and troubleshoot. FAT32 has several enhancements over FAT16. NTFS supports file and folder security, compression,

and disk quotas.