Lecture
Translation Software
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Compilers
Assemblers
Interpreter
Source code
Object Code
Program
• A program is a set of instructions for
performing a particular task.
• These instructions are just like English words.
The computer interprets the instructions as
1's and 0's.
Program
• Source Program: A program can be written in
assembly language as well as in high-level
language. This written program is called the
source program.
• Object Code: The source program is to be
converted to the machine language, which is
called an object program.
Object code, or sometimes object module, is
what a computer compiler produces
• Translator:A translator is required for such a
translation.
Translator
• Program translator translates source code of
programming language into machine
language-instruction code.
• Computer programs are written in languages
like COBOL, C, BASIC and ASSEMBLY
LANGUAGE, which should be translated into
machine language before execution.
Classification of translator
Assembler
• An assembler translates the symbolic codes of
programs of an assembly language into
machine language instructions .
• The symbolic language is translated to the
machine code in the ratio of one is to one
symbolic instructions to one machine code
instructions. Such types of languages are
called low-level languages.
• The translation job is performed either
manually or with a program called assembler.
• In hand assembly, the programmer uses the
set of instructions supplied by the
manufacturer. In this case, the hexadecimal
code for the mnemonic instruction is searched
from the code sheet. This procedure is tedious
and time-consuming. Alternate solution to this
is the use of assemblers.
• Doing this process with an assembler is fast
and facilitates the user in developing the
program speedily.
Assembler
Compiler
• Compilers are the translators, which translate all
the instructions of the program into machine
codes.
• The program, which is to be translated, is called
the source program and after translation the
object code is generated. The source program is
input to the compiler. The object code is output
for the secondary storage device. The entire
program will be read by the compiler first and
generates the object code.
• The compiler displays the list of errors and
warnings for the statements violating the
syntax rules of the language. Compilers also
have the ability of linking subroutines of the
program.
Interpreter
• In computer science, an interpreter normally means
a computer program that executes, i.e. performs,
instructions written in a programming language.
An interpreter may be a program that either
1. executes the source code directly
2. translates source code into some
efficient intermediate representation(code) and
immediately executes this
3. explicitly executes stored precompiled code made by
a compiler which is part of the interpreter system.
Linking
• C language provides a very large library, which
contains numerous functions. In some
applications of C the library may be a very
large file. Linker is a program that combines
source code and codes from the library.
Linking is the process of bringing together
source program and library code.
Operating System
• The most important program that runs on
your computer. It manages all other programs
on the machine.
• Every PC has to have one to run other
applications or programs. It’s the first thing
“loaded”.
Operating System
• It performs basic tasks, such as:
1. Recognizing input from the keyboard or
mouse.
2. Sending output to the monitor.
3. Keeping track of files and directories
4. on the disk.
5. Controlling peripheral devices such as disk
drives and printers.
Type of Operating System
• Generally, there are four types, based on the
type of computer they control and the sort of
applications they support.
Single-User Single Task
• This type manages the computer so that one
user can effectively do one thing at a time.
• Multi-user, multi-task
Allows two or more users to run programs at
the same time. Some operating systems
permit hundreds or even thousands of
concurrent users.
Real Time Operating System
• RTOS are used to control machinery, scientific
instruments, and industrial systems.
• There is typically very little user interface
capability.
• Resources are managed so that a particular
operation executes precisely the same every
time.
Single User, Multitasking
• This is the type of operating system most
desktops and laptops use today.
• Microsoft’s Windows and Apple’s MacOS are
both examples of operating systems that will
let a single user have several programs in
operation at the same time.
Malware
• Malware, short for malicious software, is
software used or created by attackers to
disrupt computer operation, gather sensitive
information, or gain access to private
computer systems.
• Malicious software is any software that the
user did not authorize to be loaded or
software that collects data about a user
without their permission
• Software deliberately designed to harm computer
systems.
• Malicious software program causes undesired
actions in information systems.
• Spread from one system to another through
• Email (through attachements)
• Infected floppy disks
• Downloading /Exchanging of corrupted files.
• Embedded into computer games
Virus
• A computer virus is a computer program that
can replicate itself and spread from one
computer to another. The term "virus" is also
commonly, but erroneously, used to refer to
other types of malware, including but not
limited to adware and spyware programs that
do not have a reproductive ability.
• A virus is a piece of code that spreads from one
computer to another by attaching itself to other
files. The code in a virus corrupts and erases files
on a user’s computer or performs other
destructive or annoying tasks when the file to
which it was attached is opened or executed.
Viruses and other types of malicious code are
frequently introduced via email attachements.The
term virus is often as an umbrella term to refer to
many types of malicious software
Trojan Horses
• A Trojan horse is a malicious program acting as a benign
application and will purposefully do something that the
user does not expect. Trojans are not viruses since they do
not replicate, but can be just as destructive.
• Trojan horses typically involves a server and a client. The
client is cleverly disguised as significant software and
positioned in peer-to-peer file sharing networks or
unauthorized download websites. Once executed, the
attacker (the person running the server) has a high level of
control over your computer based on the attacker’s
purpose.
Worm
• Computer Worms are viruses that reside in
the active memory of a computer and
duplicate themselves. They may send copies
of themselves to other computers via e-mail
and chat sessions.
Spyware
• Spyware is unwanted programs that exploit infected
computers for commercial gain. They can deliver
unsolicited pop-up advertisements, steal personal and
financial information, monitor web-browsing activity or
route "HTTP" requests to advertising sites.
• Spyware are usually bundled as hidden components in
freeware and shareware applications. If you have
download and installed an application such as peer-topeer file sharing or a screen saver, a spyware module
may be actively running on your computer at this very
moment without your knowledge.
Antivirus
Antivirus is software used to prevent, detect
and remove malware.
Information System
• Information system is an organized
combination of people ,hardware ,software
,communication network and data resources
that perform collection of data, process it and
transform it to provide in an organization
Data
• Data : are raw facts .Data is isolated values
which by themselves do not have much
significance. Data may be numbers, letters or
characters,images.
• Data is a raw material for the production of
information.
• Data is not organized and does not convey any
information.
Information
• Information is processed ,manipulated and
interpreted data.
• Information is created by defining and
organizing relationship among data.
• The processed data gives us the information
which can be used for different purposes.
Knowledge
• Knowledge is an inference or conclusion
drawn from the information
Data :8th ,August ,2008 ,China ,Olympics
Information :The Olympics are being held in China from 8th August.
Knowledge :I should plan my trip to china around 8th August.
Information System
• Information System is a set of components that
work together to achieve a common goal. A
system accept input, process it and produces an
output. A system is composed of one or more
subsystems.
• System can be open or closed
• Open system: An open system interact with other
system
• Closed System: A closed system is a stand alone
system that does not interact with other system
.
• Information system is a set of inter related
system that
• Collect data
• Manipulate data
• Disseminate data and information
• Provide feedback to meet an objective.
Feedback
Input
Output
Process
Database
• Database and database system are essential
part of our life.
• We have been interacting with non
computerized databases since long time,
remember looking for a word in a dictionary
or finding the telephone number of your
friend from a telephone directory
Computerized Databases
• Use computer to store ,manipulate and
manage databases. In our daily lives we
interact with the computerized databases
when we go for the reservation of railway
tickets ,for the searching of a book in a library
etc
Database
• Database is a repository or collection of
logically related and similar data.
• Database store similar kind of data that is
organized in a manner that the information
can be derived from it modified ,data can be
added or deleted and used when needed.
• Data is a collection or repository of data
having an organized structure and for a
specific purpose.
File oriented Approach and Database
Approach
• In the early days data was stored in files.For
an application multiples files are required to
be created.Each file stores and maintains its
own related data.For example a student
information system would include files like
student profile , student course ,student
result and student fees.
• Drawbacks of file system
• Data Redundancy: means storing the same
data at multiples locations.
• Data inconsistency
• Different file format
• Uncontrolled concurrent access
Characteristics of Database Approach
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Data redundancy is reduced.
Data inconsistency is reduced.
Data is shared.
Data security is improved
Application development time is reduced
Application Software
Apply to real-world tasks
Solves user problems
vs. OS
controls the hardware