3 Generation Languages n Oops

8/6/2019 3 Generation Languages n Oops

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3 GENERATION

LANGUAGES

AND OOPS


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Analogy with natural

languages Computer languages use a limited vocabulary

Computer problems need to be solved by breaking

down into discrete logical steps comprising 4

fundamental operations

input and output operations

arithmetic operations

Movement of operation within CPU & memory

Logical or comparison operations

Syntax rules of language to be followed

smaller and simpler than natural languages but have to

be used with great precision.


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CLASSIFICATION OF COMPUTER

LANGUAGES

MACHINE LANGUAGE

ASSEMBLY LANGUAGE

HIGH-LEVEL LANGUAGE

3rd generation 4th generation 5th generation


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MACHINE

LANGUAGE


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Machine language

the language understood by the computerwithout using a translation program

written as strings of binary 1s and 0s

It has a two part format

Operation code Operand tells the computer what tells the computer where

function to perform to find or store the data

OPCODE

(Operation code)

OPERAND

(Address/location)


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Programs written in machine

language can be executed very

fast by the computer. This is

because machine instructions

are directly understood by the

computer, and no translation

of the program is required.


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Machine dependent- due to difference in internaldesign of every type of computer machine languagediffers from computer to computer.

Difficult to program- it is difficult to program inmachine language.

Error prone - programmer has to remember opcodesand keep track of storage locations of data andinstructions.

Difficult to modify- checking machine instructions tolocate errors is difficult and time consuming.


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ASSEMBLY

LANGUAGE


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Introduced in 1952, helped in overcoming the limitations

of machine language programming as:

Using alphanumeric mnemonic codes, instead ofnumeric codes. e.g. using ADD instead of 1110 (binary) or

14 (decimal), using SUB instead of 1111 (binary) or 15

(decimal)

Allowing storage locations to be represented in the

form of alphanumeric addresses, instead of numeric.e.g. the memory locations 1000 & 1001 may be

represented as FRST & SCND

By providing additional instructions, called pseudo

instructions, in the instruction set.


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Assembler :

Translator program, which is known as an

assembler translates an assembly language

program into an equivalent machine language

program of the computer.

ASSEMBLY

LANGUAGE

PROGRAM

INPUT ASSEMBLER OUTPUT MACHINE

LANGUAGE

PROGRAM

(SOURCEPROGRAM)

ONE-TO ONE CORRESPONDENCE (OBJECTPROGRAM)

the input to the assembler is the assembly

language program (source program), its output is

the machine language program (object program)


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Computer has to run the program, also assembler

(program) to translate the original assembly

language program into its equivalent machine

language program.

Mnemonic Opcode Meaning

HLT

CLA

ADD

SUBSTA

00

10

14

1530

Halt, used at the end of program

to stop

Clear &add into A register

Add to the contents of A register

Subtract from the contents of A

register

Store A register


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START PROGRAM AT 0000

START DATA AT 1000

SET ASIDE AN ADDRESS FOR FRST

SET ASIDE AN ADDRESS FOR SCND

SET ASIDE AN ADDRESS FOR ANSR

CLA FRSTADD SCND

STA ANSR

HLT

A sample assembly language program for

adding two no. & storing the result.


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Easier to understand & use: due to the use ofmnemonics and symbolic names

Easier to locate & correct errors: programmers need

not keep track of storage locations, fewer errors are

made. Easier to modify: easier to understand, locate,

correct, and modify instructions.

No worry about addresses: need not keep track of

storage locations of the data and instructions

Easily relocatable: due to the availability of pseudo-

instructions


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Machine dependent: assembly languageprograms differ from computer to computer.

Knowledge of hardware required: assembly

languages are machine dependent, so the

programmer must have good knowledge of the

characteristics and logical structure of his

computer.

Machine level coding: Writing assembly

language programs is still time consuming and

not very easy.


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HIGH LEVEL LANGUAGES deal with

high level coding, enabling theprogrammers to write instructions

using familiar English words.

Each statement of a high levellanguage is normally a macro

instruction translated into several

machine language instructions. Thisis one to many translation.


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E.g.

consider the problem of

adding two numbers

FRST and SCND. If weuse a high level language,

only one instruction need

be written:ANSR = FRST + SCND


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There are three models of execution for

modern high-level languages:

Interpreted languages: are read and thenexecuted directly, with no compilation stage. A

program called an interpreter reads the program

line by line and executes the lines as they are read.

Compiled languages: are transformed into anexecutable form before running.

Translated languages : A language may betranslated into a low-level programming language

for which native code compilers are already widely

available.


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Machine IndependenceA program written in high-level language can be

executed on many different types of computers.

Fewer errorsWorking on high level languages allows theprogrammer to concentrate more on the logic of the

program. Thus, leads to fewer errors.

Lower program preparation costWriting programs in high level requires less time and

effort which ultimately leads to lower program

preparation cost.


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Better documentationThe statements of a program written in high level can

be easily understood by a programmer familiar with

the problem domain.

Easier to maintain

Because they are easier to understand, hence it is easierto locate, correct, insert, remove and modify

instructions.

Easier to learn and useHigh level languages are easier to learn, as they arevery familiar to the natural languages used by us .


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Lower efficiency

Program written in high level languages take more time

to execute, and require more main memory space.

Less flexibility

High level languages are less flexible than assembly

languages, because they do not normally have

instructions or mechanism to control the computers

CPU, memory and registers.


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Some examples of high level

languages:


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Third-generation languages (3GLs) are the first to

use true English-like phrasing, making them easier

to use than previous languages. E.g.: FORTRAN,COBOL, c++

4GLs may use a text-based environment (like a

3GL) or may allow the programmer to work in avisual environment, using graphical tools. E.g.

Visual Basic (VB), VisualAge

5G high-level languageswould use artificial

intelligence to create software, making 5GLsextremely difficult to develop. Solve problems using

constraints rather than algorithms, used in

Artificial Intelligence


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OBJECT

ORIENTED

PROGRAMMING

LANGUAGE


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Introduced in 1967 by the developers ofa programming language named Simula-

67.

Is a programming paradigmthat uses"objects" data structures.

Programming techniques may includefeatures such as data abstraction,encapsulation, modularity,polymorphism, and inheritance.

Java, J2EE, C++, C#, Visual Basic. NET,

Python and JavaScript are popular OOP

languages.


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3 Generation Languages n Oops