Lecture_01_30_11_11

8/3/2019 Lecture_01_30_11_11

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COMPUTING

FUNDAMENTALS

Dr. Aman-ur-Rehman

Department of Nuclear Engineering,Pakistan Institute of Engineering and Applied Sciences,

P.O. Nilore, Islamabad.

Dr. Aman-ur-Rehman

DNE, PIEAS

8/3/2019 Lecture_01_30_11_11


Course Contents

Basic components of a computer

Programming languages

Programming in FORTRAN and Applications

Introduction to MS Windows

Use of Microsoft word

Introduction to Excel

Introduction to Power Point

Dr. Aman-ur-Rehman

DNE, PIEAS

8/3/2019 Lecture_01_30_11_11


Instructors

1. Dr. Aman-ur-Rehman

(Computer Programming)

2. Dr. Abdul Jalil

(Introduction to MS Windows , Use of Microsoft word, Introduction to Power Point)

3. Dr. Jamil Ahmad

(Introduction to Excel)

4. Mr. Mazhar Hasnain (Lab. Coordinator)

Dr. Aman-ur-Rehman

DNE, PIEAS

8/3/2019 Lecture_01_30_11_11


Computer

Computer is an advanced electronic device thattakes raw data as input from the user and

processes these data under the control of set of

instructions (called program) and gives theresult (output) and saves output for the future

use.

It can process both numerical and non-

numerical (arithmetic and logical) calculations.

Dr. Aman-ur-Rehman

DNE, PIEAS

8/3/2019 Lecture_01_30_11_11


Functions of a Computer

and Computer System

A Computer has four functions

accepts data (Input)

processes data (Processing)

produces output (Output) stores results (Storage)

Computer System: All of the components of a computer system can be summarized with the simple equation

COMPUTER SYSTEM = HARDWARE + SOFTWARE+ USER

Hardware : All physical parts of the computer

Software : Programs (Software gives "intelligence" to the computer)

USER : Person, who operates computer

Dr. Aman-ur-Rehman

DNE, PIEAS

8/3/2019 Lecture_01_30_11_11


Components of a Computer

Dr. Aman-ur-Rehman

DNE, PIEAS

INPUT

Keyboard

Mouse

Scanner

Camera

Arithmetic Logic

Unit (ALU)

Control Unit

Internal Memory

Unit

OUTPUT

Screen

Printer

Plotter

Photo

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Components of a Computer

The major components of the computer are the centralprocessing unit (CPU), main memory, secondary memory,and input and output devices.

The CPU is the heart of any computer. It is divided into acontrol unit , an arithmetic logic unit (ALU), and internal memory .

The control unit of the CPU interprets the instructions of thecomputer program and it controls all the other parts of thecomputer. It also fetches data values from input devices or mainmemory and stores them in the memory registers and sends datavalues from memory registers to output device or main memory.

The ALU performs the actual mathematical calculations.

The internal memory within a CPU consists of a series of memoryregisters used for the temporary storage of intermediate resultduring calculations.

Dr. Aman-ur-Rehman

DNE, PIEAS

8/3/2019 Lecture_01_30_11_11


Main and Secondary Memory

The memory of a computer is divided into two

major types of memory: main or primary memory,

and secondary memory.

Main memory is very fast and relatively expensive. Data

stored in it can be fetched for use in less thannanosecond on a modern computer. It is not used for the

permanent storage of programs. It is also volatile.

Secondary memory consists of devices that are slower

and cheaper than the main memory. They can storemuch more information for much less money than the

main memory can. Mostly it is nonvolatile.

Dr. Aman-ur-Rehman

DNE, PIEAS

8/3/2019 Lecture_01_30_11_11


Input and Output devices

Data is entered into a computer through an inputdevice and is output through an output device.

The most common input device is on a moderncomputer is a keyboard. Other types of input

devices found on some computers are scanners andmicrophones.

Output devices permits us to use the data stored ina computer. The most common output devices on

todays computers are monitors and printers. Othertypes of output devices include plotters andspeakers.

Dr. Aman-ur-Rehman

DNE, PIEAS

8/3/2019 Lecture_01_30_11_11


Computer Program

A computer program is a sequence of instructions that are executed by a CPU.

Superscalar processors are capable of executingseveral instructions at once.

Program flow may be influenced by special

'jump' instructions that transfer execution to aninstruction other than the following one.

Dr. Aman-ur-Rehman

DNE, PIEAS

8/3/2019 Lecture_01_30_11_11


Computer Languages

(Low Level Languages) Low Level Languages: low-level languages are described as

being close to the hardware.

Low-level languages can be converted to machine codewithout using a compiler or interpreter, and the resulting coderuns directly on the processor.

A program written in a low-level language can be made to runvery fast, and with a very small memory; an equivalentprogram in a high-level language will be more heavyweight.

Low-level languages are simple, but are considered difficult touse, due to the numerous technical details which must beremembered.

Examples are Machine Level Language and Assembly language

Dr. Aman-ur-Rehman

DNE, PIEAS

8/3/2019 Lecture_01_30_11_11


Machine Level Language

Every processor or processor family has its ownmachine code instruction set.

Instructions are patterns of bits that by physical

design correspond to different commands to themachine.

The instruction set is thus specific to a class of

processors using (much) the same architecture.

Dr. Aman-ur-Rehman

DNE, PIEAS

8/3/2019 Lecture_01_30_11_11


Assembly Language

A much more readable rendition of machinelanguage, called assembly language, usesmnemonic codes to refer to machine codeinstructions

Mnemonic: For example, to remember thecolours of the rainbow, use the mnemonic"Richard Of York Gave Battle In Vain"

An Assembler is needed for conversion tomachine code

Dr. Aman-ur-Rehman

DNE, PIEAS

8/3/2019 Lecture_01_30_11_11


Merits and Demerits of

Low Level Language

Merits:

Extremely Fast executable

Best resource utilization

Customized coding

Demerits:

Suitable for small programs

Non-portable Not easy to extend / debug

Dr. Aman-ur-Rehman

DNE, PIEAS

8/3/2019 Lecture_01_30_11_11


Computer Languages

(High Level Languages)

High Level Languages: Programming languages

that are closer to human (English) language are

called High Level Languages (HLLs).

Machine Independent

Portable

Easy to Program / Debug / Extend / Modify

Compact code (smaller no. of lines)

Dr. Aman-ur-Rehman

DNE, PIEAS

8/3/2019 Lecture_01_30_11_11


Computer Languages

High Level Languages: The user friendly language

...more natural language than assembly language. Complier is needed to convert high level to machine

language

Dr. Aman-ur-Rehman

DNE, PIEAS

COBOL (COmmon Business Oriented Language), FORTRAN (FORmulaTRANslation), BASIC

(Beginner's All-purpose Symbolic Instruction Code), C, C++ etc. are the examples of High

Level Language.

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Examples of High Level Languages

Dr. Aman-ur-Rehman

DNE, PIEAS

8/3/2019 Lecture_01_30_11_11


Language Concepts Fortran, C, C++ Compiled languages i.e., source code is created with an editor as a

plain text file. Programs then needs to be compiled (converted from source code

to machine instructions with relative addresses and undefinedexternal routines still needed).

External routines are those needed to do such operations as read

data files, write to the screen, read the keyboard strokes etc.) The compiled routines (called object modules) need then to be

linked or loaded.

Linking creates an executable with relative addresses resolved and

external routine loaded from the system and user libraries.

The executable can then, in most cases, be run on any machine

with the same architecture.

Compiling and linking can be done in one user step.

Dr. Aman-ur-Rehman

DNE, PIEAS

8/3/2019 Lecture_01_30_11_11


FORTRAN (Formula Translation)

History Developed between 1954-1957 at IBM

FORTRAN II released in 1958

FORTRAN IV released in 1962 (standard for next 15 years)

FORTRAN

66ANSI standard (basically FORTRAN IV).

FORTRAN 77 standard in 1977

Fortran 90 Added new features, in 1997 Fortran 95

released (started phasing out some FORTRAN 77

features).

Fortran 2000 and 2008 have been released but we will notcover here.

Dr. Aman-ur-Rehman

DNE, PIEAS

8/3/2019 Lecture_01_30_11_11


Philosophy of FORTRAN

FORTRAN was developed at a time whencomputers needed to do numerical calculations.

Its design is based on the idea of having modules(subroutines and functions) that do calculations with

variables (that contain numeric values) and to returnthe results of those calculations.

FORTRAN programs are a series of modules that docalculations with typically the results of one module

passed to the next.Usually programs need some type of IO to get

values to computations with and to return the results.

Dr. Aman-ur-Rehman

DNE, PIEAS

8/3/2019 Lecture_01_30_11_11


FORTRAN-77

Commands are divided into executable and non-executable ones. All non-executable commandsmust appear before the executable ones.

Syntax is quite rigid (discuss later)

Basic Structure:oModule types:

Program (only one per program, optional)

Subroutine Multi-argument return

Function single return (although not forced) Block data discuss later

Dr. Aman-ur-Rehman

DNE, PIEAS

8/3/2019 Lecture_01_30_11_11


Advantages of FORTRAN-77

F77 is a very simple language

F77 is easy to learn

F77 was made for computing mathematicalformulas and operating efficiently on plain arrays

F77 is still (and will forever be?) the dominatinglanguage for numerical computing

Lots of well tested and efficient F77 libraries exist

Compilers have 50 years of experience withoptimizing F77 loops over arrays

Result: F77 is hard to beat when it comes to arrayoperations

Dr. Aman-ur-Rehman

DNE, PIEAS

8/3/2019 Lecture_01_30_11_11


Disadvantages of FORTRAN-77

The basic variables types are primitive

No struct or class construct in F77

No dynamic memory allocation

Very primitive language for text processing, lists

and more complicated data structures F77 codes are difficult to extend, maintain and re-

use

F90/F95: extension of F77 with classes

(The efficiency of F90/F95 is still problematic, andF77 programmers move very slowly to F90/F95)

Dr. Aman-ur-Rehman

DNE, PIEAS

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Lecture_01_30_11_11