Software Engineering : Computer basics - Introduction to computer

Computer Language and
Programming
Unit - 3

What does a Computer Program do?
 A computer program is:
– a set of instructions that tell a computer how to
perform a particular task.

 A programming language is a set of rules
that provides a way of telling a computer
what operations to perform.
 Some programming languages are written
for particular computing problems.
For example,
 FORTRAN for scientific applications
 COBOL for business applications
What is a Programming Language?

 English is a natural language. It has
words, symbols and grammatical rules.
 A programming language also has
words, symbols and rules of grammar.
 The grammatical rules are called syntax.
 Each programming language has a
different set of syntax rules.
Programming Language

Types of Programming Languages
High-Level Language
class Triangle {
...
float surface()
return b*h/2;
}
Middle -Level Language
LOAD r1,b
LOAD r2,h
MUL r1,r2
DIV r1,#2
RET
Low-Level Language / Executable
Machine code
0001001001000101001001
001110110010101101001.
..

 Machine languages (first-generation
languages) are the most basic type of
computer languages, consisting of strings
of numbers the computer's hardware can
use.
 Different types of hardware use different
machine code.
 For example, IBM computers use different
machine language than Apple computers.
Machine Languages

 In machine languages, instructions are
written as sequence of 1s and 0s, called
bits, that a computer can understand
directly.
 It tells the computer,
 Where to find one or two numbers or simple
pieces of data in the main memory
 To perform simple operations like add two
numbers
 Where in the main memory to put the result
 Where to find the next instruction to perform
Machine Languages

 The only language that the computer
understands is called binary or machine
language.
 Programs interact with the computer using
machine language.
 It’s difficult for humans to read or write so an
intermediate language is used to get it translated
into binary for us.
Machine Languages

 Assembly languages (second-generation
languages) are only somewhat easier to
work with than machine languages.
 To create programs in assembly language,
developers use cryptic English-like phrases
to represent strings of numbers.
 The code is then translated into object code,
using a translator called an assembler.
Assembly Languages

Assembler
Assembly
code
Object code

 Closer to English but included simple
mathematical notation.
 Programs written in source code which
must be translated into machine language
programs called object code.
 The programmer generates the source
code.
 The interpreter or compiler generates the
object code (machine code)
Higher-Level Languages

Translating High Level Languages
to Machine Code`
Two ways to generate object code:
• An interpreter translates the high-level
instructions into machine code, line by
line, as the program is running
• A compiler translates the entire program
into machine code before running the
program

• Third-generation languages
• Fourth-generation languages
• Fifth-generation languages
 Higher-level programming languages are
divided into three "generations," each
more powerful than the last:
Higher-Level Languages

FORTAN C
COBOL C++
BASIC Java
Pascal ActiveX
• Third-generation languages (3GLs) are the first to
use true English-like phrasing, making them easier
to use than previous languages.
• 3GLs are portable, meaning the object code created
for one type of system can be translated for use on a
different type of system.
• The following languages are 3GLs:
Higher-Level Languages –
Third-Generation Languages

Visual Basic (VB)
VisualAge
Authoring environments
• Fourth-generation languages (4GLs) are even easier
to use than 3GLs.
• 4GLs may use a text-based environment (like a 3GL)
or may allow the programmer to work in a visual
environment, using graphical tools.
• The following languages are 4GLs:
Higher-Level Languages -
Fourth-Generation Languages

• Fifth-generation languages (5GLs) are an issue of
debate in the programming community – some
programmers cannot agree that they even exist.
• These high-level languages would use artificial
intelligence to create software, making 5GLs extremely
difficult to develop.
• PROLOG – A language used to program Artificial
Intelligence
Higher-Level Languages -
Fifth-Generation Languages

 FORTRAN
 FORmula TRANslation.
 Developed by John Backus
 Developed at IBM in the mid-1950s.
 Designed for scientific and mathematical
applications by scientists and engineers.
Procedural Languages

 COBOL
 COmmon Business Oriented Language.
 Developed in 1959.
 Created by Grace Hopper
 Designed to be common to many different
computers.
 Typically used for business applications.
Procedural Languages

 LISP
 LISt Processing.
 Developed in 1958.
 Created by John McCarthy
 First Functional Language
Functional Language

 BASIC
 Beginner’s All-purpose Symbolic Instruction
Code.
 Developed at Dartmouth College in mid 1960s.
 Developed as a simple language for students
to write programs with which they could
interact through terminals.
Programming Languages

 C
 Developed by Bell Laboratories in the early
1970s.
 Provides control and efficiency of assembly
language while having third generation
language features.
 Often used for system programs.
 UNIX is written in C.
Programming Languages

 SIMULA
 First object-oriented language
 Developed by Ole Johan Dahl in the 1960s.
 SMALLTALK
 First purely object-oriented language.
 Developed by Xerox in mid-1970s.
 Still in use on some computers.
Object-Oriented Programming
Languages

 C++
 It is C language with additional features.
 Widely used for developing system and
application software.
 Graphical user interfaces can be developed
easily with visual programming tools.
Languages

 JAVA
 An object-oriented language similar to C++
that eliminates lots of C++’s problematic
features
 Allows a web page developer to create
programs for applications, called applets that
can be used through a browser.
 Objective of JAVA developers is that it be
machine, platform and operating system
independent.
Languages

Chapter 3 (Questions)
 What is program?
 What is programming Language?
 What are the different programming
language generations?
 What are the differences between
HLL and LLL?
 Explain computer language types
with example.

Software Engineering : Computer basics - Introduction to computer

Recommended

More Related Content

Similar to Software Engineering : Computer basics - Introduction to computer (20)

Recently uploaded (20)

Software Engineering : Computer basics - Introduction to computer