Introduction



Introduction

OPERATING SYSTEM

Before starting the discussion on Operating System, let us start from the concept of hardware and software. Hardware is the circuitry part of the computer by which it actually works. Integrated circuits (IC), floppy drive, hard disk drive, and power system, used in the computer are all included in the group of hardware. In contrast, Software is the instructions and data part, which are supplied to the computer to solve a problem or task. So, when we instruct computer to do certain tasks, we actually use the software part. An Operating System acts between the hard and the software part, but software acts between the user and the Operating System part. Thus Operating System acts as the link between these two. It also used to manage various resources (e.g. memory) of the computer, to control the overall operations of the computer.

The core part of the Operating System resides in the memory of computer and is known as ‘resident program’. The other main part of the Operating System is known as ‘transient program’ which consist of translator units like compilers, interpreters, and utility programs.

How it works

We have already discussed that Operating System is the link between software and hardware. Any software instruction is actually carried out with the help of hardware circuitry. Operating System thus relates two. Besides this, the important necessity of an Operating System is that it sets the environment and logic unit of a computer. This includes the memory steps like memory management, I/O device management and many more. With the use of high level instructions (i.e. with the use of programming languages closer to English) we send the instructions to computer. These high level instructions are converted to their equivalent machine level codes with the help of the translator units like interpreter or compilers. These machines language code are used by the Operating System in order to carry out the task with the help of the stored instructions in the ROM BIOS chip. So, Operating System does the basic tasks, which is absolutely necessary to run the program and to work with smoothly. So, without loading the Operating System, a computer cannot work with user.

Disk Operating System:

Microsoft’s MS-DOS is an Operating System. Basically an Operating System is a group of programs that acts as translator between user and computer. MS-DOS is “Silent partner” when user is using the computer; it can be compared to electricity in a house – you need it for the toaster and blender to work, but you are not always that it is there.

MS-DOS is a disk operating system. That is, the programs can be used on floppy disks or hard disk. Computers with hard disk can usually store more information than machine that uses only floppy disks. User can use MS-DOS either on floppy disks or in the hard disks. When user loads MS-DOS in the computer, they can play computer games, run programs, compose letters and reports and run languages like BASIC. MS-DOS also lets user to use devices such as printers and disk drives with the computer.

Installing DOS:

This section will show how to install DOS in the computer. To start installing, follow these steps:

1. First make sure that the computer is turned off.

2. If there is a floppy system disk, take the disk out of the protective envelope.

3. Insert the MS-DOS system disk in drive A.

4. Now, turn on your computer.

The light on the disk drive will glow and you will hear some whirring noises as your computer reads the disk.

Booting MS-DOS:

After switch on the machine, a PC beeps and asks to insert the disk Operating System in drive A. For a correct and good disk, it starts working, while for others it prompts an error message. This is known booting, more precisely cold booting. The term ‘cold’ is added to mean that the system was not energized before the boot.

When we switch on the computer, a beep sound takes place. It indicates that all proper voltages (to run a PC range of computer it needs +5V, -5V, +12V, -12V supply voltages) are available to proper places of the machine and all input – outputs units, memory and all the associated circuitry are in working order. Beep sound is the acknowledge of the same given the Central Processing unit (CPU), and the CPU gets information from ‘power good signal’ and from other signals. A ‘POWER GOOD SIGNAL’ is a logical signal, which will be available only if all rated voltages are available to the machine. These voltages are available through power supply unit also known as SMPS, stands for Switch Mode Power Supply.

After the switch on and after completion of the POST, machine loads the start up program from the ROM BIOS, and following these, the next instructions is to check all the RAM units. After this test is over, if there is a system disk is present in the drive, it loads the address of the boot record in to memory from the track 0, sector 1 of the system disk.

By the term loading the Disk Operating System we mean to load the system files. The system files are IO.SYS, MSDOS.SYS and PUTER. The two files IO.SYS and MSDOS.SYS are hidden files.

After the DOS is loaded in to the memory of the computer, the screen should look like this:

Current date is Thu 06-01-2000

Enter new date (mm-dd-yy):

Current time is 9:56:09:08

Enter new time:

MS-DOS asks you to provide the date and time. Type the date in the mm-dd-yy format and time can be entered in two formats. One is 24 hours from and other is 12 hours AM/PM form.

Cold Booting

The process of loading system is known as ‘Booting’. The term ‘cold’ is added to mean that the system was not energized before the boot. So, in this case computer starts from very beginning i.e. from POST including RAM test.

Warm Booting

If for any reason, the computer ‘hangs’ at the time of working, it should be again started from the beginning. This can be easily can be done by pressing the Ctrl + Alt + Del. This can only work if the keyboard remains in active state.

INTERNAL COMMANDS

Available DOS commands are of two types. These are Internal Commands and External Commands. Internal commands are those, which are loaded in to the memory automatically at the time o loading the Operating System. We can always use these commands after booting the machine. But, at the time of listing the files these are not displayed.

EXTERNAL COMMAND

External commands are auxiliary program files, which may or may not be present in the disk. We can use these commands only if the corresponding program files are available. The names of the command files are displayed at the time of listing the files.

We will discuss the internal commands of DOS in this chapter along with their uses. The Commands are: CLS, DIR, CD, CHDIR, COPY, DEL, ERASE, MD, MKDIR, RD, DATE, TIME, TYPE, VER, REN, RENAME, PROMPT, BREAK, VERIFY, PATH, and SET.

Few DOS Commands:

CHKDSK

Checks a disk and displays a status report.

CHKDSK [drive:] [[path] filename] [/F] [/V]

[Drive:] [Path] Specifies the drive and directory to check.

Filename Specifies the file(s) to check for fragmentation.

/F Fixes errors on the disk.

/V Displays the full path and name of every file on the disk.

Type CHKDSK without parameters to check the current disk.

Instead of using CHKDSK, try using SCANDISK. SCANDISK can reliably detect and fix a much wider range of disk problems.

FDISK

Configures a hard disk for use with MS-DOS.

FDISK [/STATUS] /X

/STATUS Displays partition information.

/X Ignores extended disk-access support. Use this switch if you receive disk

access or stack overflow messages.

SCANDISK

Runs the Scandisk disk-repair program.

To check and repair a drive, use the following syntax:

SCANDISK [drive: / ALL] [/CHECKONLY / AUTOFIX [/NOSAVE]] [/SURFACE]

To check and repair uncounted DriveSpace compressed volume file, use:

SCANDISK drive: \ DRVSPACE.nnn [/CHECKONKY / AUTOFIX [/NOSAVE]]

To examine a file for fragmentation, use the following syntax:

SCANDISK /FRAGEMENT [drive:] [path] filename

To undo repairs you made previously, use the following syntax:

SCANDISK /UNDO [drive:]

For [drive:], specify the drive containing your Undo disk.

/ALL Checks and repairs all local drives.

/AUTOFIX Fixes damage without prompting.

/CHECKONLY Checks a drive, but does not repair any damage.

/CUSTOM Configures and runs Scandisk according to SCANDISK.INI settings

/NOSAVE With /AUTOFIX, deletes lost clusters rather than saving as files.

/NOSUMMARY With /CHECKONLY or /AUTOFIX, prevents Scandisk from stopping at

summary screens.

/SURFACE Performs a surface scan after other checks.

/MONO Configures Scandisk for use with a monochrome display.

To check and repair the current drive, type SCANDISK without parameters.

FORMAT

Formats a disk for use with MS-DOS.

FORMAT drive: [/V [: label]] [/Q] [/F: size] [/B /S] [/C]

FORMAT drive: [/V [: label]] [/Q] [/T: tracks /N: sectors] [/B /S] [/C]

FORMAT drive: [/V [: label]] [/Q] [/1] [/4] [/B /S] [/C]

FORMAT drive: [/Q] [/1] [/4] [/8] [/B /S] [/C]

/V [: label] Specifies the volume label.

/Q Performs a quick format.

/F: size Specifies the size of the floppy disk to format (such as 160, 180, 320,

360, 720, 1.2, 1.44, 2.88).

/B Allocates space on the formatted disk for system files.

/S Copies system files to the formatted disk.

/T: tracks Specifies the number of tracks per disk side.

/N: sectors Specifies the number of sectors per track.

/1 Formats a single side of a floppy disk.

/4 Formats a 5.25-inch 360K floppy disk in a high-density drive.

/8 Formats eight sectors per track.

/C Tests clusters that are currently marked “bad”.

COPY CON

Copies one or more files to another location.

COPY [/A /B] source [/A /B] [+ source [/A /B] [+ …]] [destination [/A /B]] [/V] [/Y /-Y]

Source Specifies the file or files to be copied.

/A Indicates an ASCII text file.

/B Indicates a binary file.

Destination Specifies the directory and/or filename for the new file (s).

/V Verifies that new files are written correctly.

/Y Suppresses prompting to confirm you want to overwrite an

existing destination file.

/-Y Causes prompting to confirm you want to overwrite an existing

destination file.

The switch /Y may be present in the COPYCMD environment variable.

This may be overridden with /-Y on the command line

To append files, specify a single file for destination, but multiple files for source (using wildcards or file1+file2+file3 format).

COPY

Copies one or more files to another location.

COPY [/A /B] source [/A /B] [+ source [/A /B] [+ …]] [destination [/A /B]] [/V] [/Y /-Y]

Source Specifies the file or files to be copied.

/A Indicates an ASCII text file.

/B Indicates a binary file.

Destination Specifies the directory and/or filename for the new file (s).

/V Verifies that new files are written correctly.

/Y Suppresses prompting to confirm you want to overwrite an

existing destination file.

/-Y Causes prompting to confirm you want to overwrite an

existing destination file.

The switch /Y may be present in the COPYCMD environment variable.

This may be overridden with /-Y on the command line

To append files, specify a single file for destination, but multiple files for source (using wildcards or file1+file2+file3 format).

DIR

Displays a list of files and subdirectories in a directory.

DIR [drive:] [path] [filename] [/P] [/W] [/A [[:] attributes]]

[/O [[:] sort order]] [/S] [/B] [/L] [/V]

[Drive:] [Path] [Filename]

Specifies drive, directory, and/or files to list. (Could be enhanced file specification or multiple file specs.)

/P Pauses after each screen of information.

/W Uses wide list format.

/A Displays files with specified attributes.

Attributes D Directories

H Hidden files

S System files

R Read-only files

A Files ready for achieving

- Prefix meaning not

/O List by files in sorted order.

Sort order N By name (alphabetic)

E By extension (alphabetic)

S By size (smallest first)

D By date & time (earliest first)

G Group directories first

A By Last Access Date (earliest first)

- Prefix to reverse order

/S Displays files in specified directory and all subdirectories.

/B Uses bare format (no heading information or summary).

/L Uses lowercase.

/V Ver Bose mode.

Switches may be preset in the DIRCMD environment variable. Overridden preset switches by prefixing any switch with – (hyphen)—for example, /-W.

MKDIR/MD

Creates a directory.

MKDIR [drive:] path

MD [drive:] path

REMOVE DIRECTORY (RD)

Removes (deletes) a directory.

RMDIR [drive:] path

RD [drive:] path

CHANGE DIRECTORY (CD)

Displays the name of or changes the current directory.

CHDIR [drive:] [path]

CHDIR[..]

CD [drive:] [path]

CD [..]

.. Specifies that you want to change to the parent directory.

Type CD drive: to display the current directory in the specified drive.

Type CD without parameters to display the current drive and directory.

TYPE

Displays the contents of text files.

TYPE [drive:] [path] filename

DELETE (DEL)

Deletes one or more files.

DEL [drive:] [path] filename [/P]

ERASE [drive:] [path] filename [/P]

[/drive:] [path] filename multiple Specifies the file(s) to delete. Specify files

by using wildcards.

/P Prompts for confirmation before deleting each file.

CLEAR SCREEN (CLS)

Clears the screen.

CLS

RENAME (REN)

Renames a file/directory or files/directories.

RENAME [drive:] [path] [directoryname1 filename1] [directoryname2 filename2]

REN [drive:] [path] [directoryname1 filename1] [directoryname2 filename2]

Note that you cannot specify a new drive or path for your destination.

PATH

Displays or sets a search path for executable files.

PATH [[drive:] path [;…]]

PATH ;

Type PATH; to clear all search-path settings and direct Windows to search only in the current directory.

Type PATH without parameters to display the current path.

VERSION

Displays the Windows version.

VER

EXCLUSIVE COPY (XCOPY)

Copies files (except hidden and system files) and directory trees.

XCOPY source [destination] [/A /M] [/D:date] [/P] [/S [/E]] [/V] [/W]

Source Specifies the file(s) to copy.

Destination Specifies the location and/or name of new files.

/A Copies files with the archive attribute set, doesn’t change the

attribute.

/M Copies files with the archive attribute set, turns off the archive

attribute.

/D:date Copies files changed on or after the specified date.

/P Prompts you before creating each destination file.

/S Copies directories and subdirectories except empty ones.

/E Copies any subdirectories, even if empty.

/V Verifies each new file.

/W Prompts you to press a key before copying.

ATTRIB

Displays or changes file attributes.

ATTRIB [+R -R] [+A -A] [+S -S] [+H -H] [[drive:] [path] filename] [/S]

+ Sets an attribute.

- Clears an attribute.

R Read-only file attribute.

A Archive file attribute.

S System file attribute.

H Hidden file attribute.

/S Processes files in all directories in the specified path.

COMMAND

Starts a new copy of the Windows Command Interpreter.

COMMAND [[drive:] path] [device] [/E:nnnnn] [/L:nnnn] [/U:nnn] [/P] [/MSG] [/LOW] [/Y [C K] command]]

[drive:] path Specifies the directory containing .

device Specifies the device to use for command input and output.

/E:nnnnn Sets the initial environment size to nnnnn bytes. (nnnnn should be between 256 and 32,768).

/L:nnnn Specifies internal buffers length (requires /P as well). (nnnn should be between 128 and 1,024).

/U:nnn Specifies the input buffer length (requires /P as well). (nnn should be between 128 and 255).

/P Makes the new Command Interpreter permanent (can’t exit).

/MSG Stores all error messages in memory (requires /P as well).

/LOW Forces COMMAND to keep its resident data in low memory.

/Y Steps through the batch program specified by /C or /K.

/C command Executes the specified command and returns.

/K command Executes the specified command and continues running.

EDIT

MS-DOS Editor Version 2.0.026 Copyright © Microsoft Corp 1995.

EDIT [/B] [/H] [/R] [/S] [/] [/?] [file(s)]

/B - Forces monochrome mode.

/H - Displays the maximum number of lines possible for your hardware.

/R - Load file (s) in read-only mode.

/S - Forces the use of short filenames.

/ - Load binary file(s), wrapping lines to characters wide.

/? - Displays this help screen.

[file] - Specifies initial files(s) to load. Wildcards and multiple file specs can be given.

VERIFY

Tells Windows whether to verify that your files are written correctly to a disk.

VERIFY [ON OFF]

Type VERIFY without a parameter to display the current VERIFY setting.

SYS

Copies MS-DOS system files and command interpreter to a disk you specify.

SYS [drive1:] [path] drive2:

[Drive1:] [Path] Specifies the location of the system files.

Drive2: Specifies the drive the files are to be copied to.

PAUSE

Suspends processing of a batch program and displays the message:

Press any key to continue….

PAUSE

EXIT

Quits the program (command interpreter).

EXIT.

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