Transcript Operating Systems

Unit 3: Software Systems
• 3.1 Software Basics
• 3.2 Application Software
• 3.3 Operating Systems
and Applications
• 3.4 DOS Commands
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Unit 3.1: Software Basics
Software – Computer programs and the data used by the program. It is consists
of computer program, support modules, and data modules that work together
to provide a computer with the instructions and data necessary for carrying out
a specific type of task.
Computer Program – is a set of self-contained instructions that tells a
computer how to solve a problem or carry-out a task. It can be started or “run”
by a computer user. It contains files such as main executable file, which is a
program that you run to start the software.
Support Module – provides an auxiliary set of instructions that can be used in
conjunction with the main software program. It is not designed to be run by a
computer user. These modules are “called” by the computer program.
Data Module – contains data that is necessary for a task, but not supplied by
the user.
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Software Basics
Computer Programmers – write the instructions for the
computer programs and support modules that become the
components of a computer software programs.
Software Publishers – companies that specialize in packaging,
marketing, and selling commercial software.
Computer Language – provides the tools that a programmer
uses to create software. These languages help the programmer
produce a lengthy list of instructions, called, source code, that
defines the software environment in every detail.
High-Level Language – have similarities to human languages
and produce programs that are fairly easy to test and modify.
Examples are C++, Visual Basic, Java, and Cobol
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Software Basics
Machine Language – the only language the microprocessor can
understand. The instruction set that is hard-wired within the
microprocessor’s circuits.
The process of translating high-level languages into machine language
can be accomplished by two special types of programs:
• Compiler – translates all of the instructions in a program as a single
batch, and the resulting machine language instructions, called object
code, are placed in a new file.
• Interpreter – converts one instruction at a time while the program
is running. This method of converting high-level instructions into
machine language is more common with Wed-based programs called
scripts. An interpreter reads the first instruction in a script, converts
it into machine language, and then sends it to the microprocessor. To
run a script, your computer must have the corresponding interpreter
program.
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Four Generations of Computer
Software
• first generation: machine language
• second generation: assembly language
• third generation: high-level programming languages,
such as C, C++, and Java.
• fourth generation: programming languages closer to
human languages than typical high-level programming
languages. Main categories are query languages and
report generators.
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Software Basics
Software Categories:
• Application Software
It is the software that provides the computer with
instructions for each of these uses. The primary purpose
of application software is to help people carry out tasks
using a computer.
• System Software
The primary purpose of system software, which is the
computer’s operating system, device drivers, and utilities,
is to help the computer carry out basic operating
function.
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Software Basics
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Licensed Software
A software license or “license agreement” is a legal
contract that defines the ways in which you may use a
computer program.
Installation Agreement – displayed on the screen when
you first install the software. Software licenses are often
lengthy and written in ‘legalese,” but your legal right to
use the software continues only as long as you abide the
by the terms of the software license.
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Licensed Software
Types of Software License:
• Shrink–Wrap License
• Single-User License
• Multiple-User License
• Concurrent-Use License
• Site License
• Shareware
• Public Domain Software
• Freeware
• Open Source Software
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Licensed Software
• Shrink-Wrap License
When a software has a shrink-wrap license, you agree to
the terms of the software license by opening the package.
If you do not agree with the terms, you should return the
software in its unopened package.
• Single-User License
This type of license limits the use of the software to only
one user at a time. Most “commercial software” is
distributed with a single-user license.
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Licensed Software
• Multi-User License
This type of license allows more than one person to use a
particular software package. This type of license is beneficial in
cases where users each requires their own personalized version
of the software. Ex: electronic mail program.
• Concurrent-Use License
This license allows a certain number of copies of the software
to be used at the same time.
Ex: A company may use a word processor up to 5 users. This
license are usually priced in Increments.
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Licensed Software
• Site License
This type of license generally allows the software to be used on
any and all computers at a specific location, such as within a
corporate office building or a university campus. A site license
is priced at a flat rate. Ex. P 350,000.00 per site.
• Shareware
Shareware is copyrighted software marketed under a “try
before you buy” policy. It usually includes a license that allows
you to use the software for a trial period. If you want to use it
beyond the trial period, you should send a registration fee.
Typically you can make copies and give It to others. This will
cause a low-cost marketing and distribution channel.
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Licensed Software
• Public Domain Software
This type of license is not protected by copyright because the
copyright has expired, or the author has placed the program in
public domain, making it available without restriction. It may be
freely copied, distributed, and even resold. Its primary
restriction is that you are not allowed to apply for a copyright on
it.
• Freeware
It is a copyrighted software, which is available for free. The
license for freeware permits you to use the software, copy it,
and give it away; but does not permit you to alter it or sell it.
Many utility programs, device drivers, and some games are
available as freeware.
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Licensed Software
• Open Source Software
It makes the uncompiled program instructions available to
programmers who want to modify and improve the
software. Open source software may be sold or
distributed free of charge, but it must include the
uncompiled “source code.” Examples are Linux and
FreeBSD.
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Unit 3.2 Application Software
Applications software (also called end-user
programs) includes database programs, word
processors,
and
spreadsheets.
Figuratively
speaking, applications software sits on top of
systems software because it is unable to run
without the operating system and system utilities.
In other words, applications software are
merely tools to help the users (people) finish
their day to day task.
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Application Software
• Common Examples of Application
software
1. Documents (MS word, wordperfect)
2. Database (SQL, MSaccess)
3. Image (adobe PS, corel draw)
4. Music and audio (mp3, realplayer)
5. Games (war craft, counter strike)
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Unit 3.3: Operating Systems
and Application
Operating System
Operating System is defined as a system software, which acts
as the master controller for all the activities that take place
within a computer system. An operating system is an integral
part of virtually every computer system, including
supercomputers, mainframes, servers, workstations, video
game systems, handhelds, and personal computers.
The operating system interacts with application software,
device drivers, and hardware to manage a computer’s
resources. Resource refers to any component that is required
to perform work.
The operating system allocates a specific area of RAM for each
program that is open and running.
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Operating Systems
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Operating Systems
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Operating Systems
An operating system acts as a filing clerk that stores and
retrieves files from your disks and CDs. It remembers the
names and locations of all your files, and keeps track of
empty spaces where new files can be stored.
The operating system communicates with device driver
software so that data can travel smoothly between the
computer and these peripheral devices. It ensures that
input and output proceeds in an orderly manner, using
queues and buffers to collect and hold data while the
computer is busy with other tasks.
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Operating Systems
A user interface can be defined as the combination of
hardware and software that helps people and computers
communicate with each other. The computer’s user
interface includes the mouse and keyboard that accept
your input and carry out your commands, as well as
display device that provides cues to help you use
software, and displays error messages that alert you to
problems. An operating system typically provides user
interface tools, such as menus and toolbar buttons.
Most computers today feature a graphical user interface
(GUI or gooey) provides a way to point and click a mouse
to select menu options and manipulate graphical objects
that are displayed in the screen.
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Operating Systems
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Operating Systems
The operating system program is quite large, so most of it
is stored in the hard disk. The operating system’s small
boot strap program is stored in ROM, and provides the
instructions needed to load the core parts into memory
when the system boots. It is a program in ROM and
initializes the operating system on a computer.
The core part of the operating system called kernel
provides the most essential operating system services,
such as memory management and file access.
Other parts of the operating system, such as
customization utilities are loaded into the memory as
they are needed.
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Operating Systems
Utilities are helpful tools that you can use to control and
customize your computer equipment and work
environment.
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Operating Systems
Operating System Categories:
• Single-User System – expects to deal with one set of
input devices – those that can be controlled by one user
at a time. Operating system for handheld computers and
many personal computers fit into this category.
• Multi-User System – designed to deal with input,
output, and processing requests from many users all at
the same time. One of its most difficult responsibilities is
to schedule all of the processing requests that must be
performed by a centralized computer.
• Network Operating System – it is also referred to as
“server computing system” provides communications and
routing services that allow computers to share data,
programs, and peripheral devices. Example is Novell.
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Operating Systems
• Multitasking Operating System – provides process and
memory management services that allow two or more
programs to run simultaneously. Most of today’s personal
computer operating systems offer multitasking services.
• Desktop Operating System – designed for personal
computer. Examples are Windows ME or MAC OS. These
operating systems are designed to accommodate a single
user, but may also provide networking capability. Today’s
desktop operating systems invariably provide multitasking
capabilities.
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BIOS: Steps in Boot Process
Power-On
BIOS begins to execute initiates POST
Enables Video Card and Displays Information
Determine amount of DRAM
Perform Memory Test
Check Expansion Cards and Adapters
Initialize Expansion Cards and Adapters
Display System Information
Load OS thru Master Boot record
Operating System Operational
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Unit 3.4 DOS Commands
Disk Operating System was developed by Microsoft and
introduced on the original IBM PC in 1982. Although IBM
called the operating system PC-DOS, Microsoft called it to
other companies under then name MS-DOS.
Disk Operating System is a command-line user interface.
MS-DOS 1.0 was released in 1981 for IBM computers and
the latest version of MS-DOS is MS-DOS 6.22 released in
1994. While MS-DOS is not commonly used by itself today,
it still can be accessed from Windows 95, Windows 98 or
Windows ME by clicking Start / Run and typing command
or CMD in Windows NT, 2000 or XP.
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Path
• What is a path in DOS?
In DOS and Windows
systems, a path is a list of
directories
where
the
operating system looks for
executable files if it is
unable to find the file in the
working directory. You can
specify the list of directories
with the PATH command.
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Kinds of path
• Absolute path
An absolute path name describes a file's location as a
fixed address, beginning with the top (the server's
name), and moving down to the file specified.
• Relative path
A relative path name describes the location of file (b)
in relation to the location of the current file (a):
whether it is seated in a folder above it, next to it
(sharing the same folder), or in a folder below it. In all
cases, the description is relative to the location of the
current file.
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Wildcards
• Files have unique names, but sometimes you
might want to refer to more than one file.
• The asterisk (*) is a wild card character used to
represent a group of characters in the filename
or extension.
• The question mark (?) is a wild card character
used to represent a single character in the
filename or extension.
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DOS Commands
CD and CHDIR (Change Directory) is a command used to
switch directories in MS-DOS.
Syntax:
CD[..]
CHDIR[drive:][path]
CHDIR[..]
CD[drive:][path]
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DOS Commands
Examples:
cd\ - Goes to the highest level the root of the drive.
cd.. - Goes back one directory. For example if you are within the
C:\WINDOWS\COMMAND> directory this would take you to
C:\WINDOWS>
cd windows - If present would take you into the Windows directory.
Windows can be substituted with any other name.
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DOS Commands
CLS is a command which allows the user to clear
the complete contents of the screen and leave
only a prompt.
Syntax:
CLS
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DOS Commands
COPY allows the user to copy one file from one source to another.
SYNTAX:
Copies one or more files to another location.
COPY [/A | /B] source [/A | /B] [+ source [/A | /B] [+ ...]] [destination] [/A |
/B]] [/V] [/Y | /-Y]
Source
/A
/B
Specifies the file or files to be copied.
Indicates an ASCII text file.
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.
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DOS Commands
EXAMPLES:
copy *.* a:
This would copy all files in the directory currently in to the floppy
disk in drive a
copy autoexec.bat c:\windows
This would take the autoexec.bat usually found at root and copy it
into the windows directory the autoexec.bat can be substituted for
any file(s).
copy win.ini c:\windows /y
This would copy the win.ini file which is already in your windows
directory to the windows directory without prompting if you wanted
to overwrite the file or not.
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DOS Commands
Del which is short for delete and is a command used to delete files
permanently from the computer.
SYNTAX
Deletes one or more files.
DEL [drive:][path]filename [/P]
ERASE [drive:][path]filename [/P]
[drive:][path]filename Specifies the file(s) to delete. Specify
multiple
files by using wildcards.
/P Prompts for confirmation before deleting each file.
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DOS Commands
EXAMPLES:
del test.tmp
Deletes the test.tmp in the directory that you currently are in, if the
file exists.
del c:\windows\test.tmp
Delete the c:\windows\test.tmp in the windows directory if it exists.
del c:\windows\temp\*.*
(* is for wild character(s)) *.* indicates that you would like to delete all
files in the c:\windows\temp directory.
del c:\windows\temp\?est.tmp
(? is a single wild character for one letter) This command would delete
any file ending with est.tmp such as pest.tmp or zest.tmp...
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DOS Commands
Deltree which is short for delete and is a command used to delete files
permanently from the computer.
Deletes a directory and all the subdirectories and files in it.
To delete one or more files and directories: DELTREE [/Y] [drive:]path
[[drive:]path[...]]
/Y
Suppresses prompting to confirm you want to delete the
subdirectory.
[drive:]path
Specifies the name of the directory you want to delete.
EXAMPLE:
deltree c:\windows\fake010 = Deletes the fake010 directory and everything in it.
Note: deltree command only works for Mircosoft Windows Me and previous
versions. For Windows XP, deltree’s functionality is combined already at rd
command.
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DOS Commands
The dir command allows you to see the available files in the current and
or parent directories.
SYNTAX:
Displays a list of files and subdirectories in a directory.
DIR [drive:][path][filename] [/P] [/W] [/A[[:]attributes]]
[/O[[:]sortorder]] [/S] [/B] [/L] [/V]
[drive:][path][filename] Specifies drive, directory, and/or files to list.
(Could be enhanced file specification or multiple filespecs.)
/P
Pauses after each screenful of information.
/W
Uses wide list format.
D
Directories
R
Read-only files
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DOS Commands
/A
/O
/S
/B
/L
/V
attributes:
H
Hidden files
A
Files ready for archiving
S
System files
- Prefix meaning not
List by files in sorted order, sortorder:
N By name (alphabetic)
S By size (smallest first)
E By extension (alphabetic)
D By date & time (earliest first)
G Group directories first
- Prefix to reverse order
A By Last Access Date (earliest first)
Displays files in specified directory and all
subdirectories.
Uses bare format (no heading information or
Uses lowercase.
Verbose mode.
summary).
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DOS Commands
EXAMPLES:
dir = Lists all files and directories in the directory that you are currently
in.
dir /s = Lists the files in the directory that you are in and all sub
directories after that directory, if you are at root "C:\>" and type this
command this will list to you every file and directory that is on the
computer.
dir /p = If the directory has a lot of files and you cannot read all the files
you can use this command and it will display all files one page at a time.
dir /w = If you don't need the info on the date / time and other
information on the files you can use this command to list just the files
and directories going horizontal taking as little as space needed.
dir /s /w /p = This would list all the files and directories in the current
directory and the sub directories after that in wide format one page at a
time.
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DOS Commands
The move command allows you to move files or directories from one folder
to another or from one drive to another.
Syntax:
Moves files and renames files and directories.
•To move one or more files: MOVE [/Y | /-Y] [drive:][path]filename1[,...]
destination
•To rename a directory: MOVE [/Y | /-Y] [drive:][path]dirname1 dirname2
[drive:][path]
filename1 Specifies the location and name of the file or files you want to
move. Destination Specifies the new location of the file. Destination can
consist of a drive letter and colon, a directory name, or a combination.
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DOS Commands
If you are moving only one file, you can also include a filename if you
want to rename the file when you move it. [drive:][path]dirname1
Specifies the directory you want to rename. dirname2 Specifies the
new name of the directory. /Y Suppresses prompting to confirm
creation of a directory or overwriting of the destination. /-Y Causes
prompting to confirm creation of a directory or overwriting of the
destination.
Example:
move c:\windows\temp\*.* c:\temp - This would move the files of
c:\windows\temp to the temp directory in root, this is of course
assuming you have the windows\temp directory.
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DOS Commands
RMDIR or RD removes empty directories in DOS. To delete directories
with files or directories within them the user must use the deltree
command.
SYNTAX:
Removes (deletes) a directory.
RMDIR [drive:]path
RD [drive:]path
EXAMPLE:
rmdir c:\test - This would remove the test directory if empty if you
want to delete directories that are full use the deltree command.
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DOS Commands
REN or RENAME used to rename files and directories from the original
name to a new name.In earlier releases of MS-DOS instead of using
ren or rename you need to use the move command to rename your
MS-DOS directories or files.
SYNTAX:
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.
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DOS Commands
EXAMPLES:
rename c:\chope hope - Rename the directory chope to
hope.
rename *.txt *.bak - Rename all text files to files with
.bak extension.
rename * 1_* - Rename all files to begin with 1_. The
asterisk (*) in this example is an example of a wild
character because nothing was placed before or after the
first asterisk this means all files.
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DOS Commands
MD allows you to create your own directories in DOS.
SYNTAX:
Creates a directory.
MKDIR [drive:]path
MD [drive:]path
EXAMPLE:
md test - This would make a test directory in the
directory that you are currently in.
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