Computer Science & Engineering Semester 1

1. Lecture 1

2. Upama Kabir, PhD
Professor
Computer Science and Engineering
Dhaka University
Contact: upama@cse.du.ac.bd
ACCE 2204: Fundamentals of Computer Science and Engineering
Lecture 1

3. Books Recommended:

Peter Norton: Introduction to Computers

Professor M Lutfar Rahman & M. Alamgir Hossain:
Computer Fundamentals
Distribution of Marks:

Class Attendance : 5

Mid Term – I: 10

Mid Term – II: 10

Lab: 5

Semester Final: 70

4. An Overview of the Computer System

5. This lecture includes the following sections:
• The Parts of a Computer System
• Looking Inside the Machine
• Software: Bringing the Machine to Life

6. The Parts of a Computer System
• What is a Computer?
• Hardware
• Software
• Data
• Users

7. • A computer can convert data into information that is
useful to people.
• A complete computer system includes four distinct
parts:
Hardware
Software
Data
User
What is a Computer?
A computer is an electronic device used to process data.

9. • A computer's hardware consists of electronic
devices; the parts you can see and touch.
• The term "device" refers to any piece of hardware
used by the computer, such as a keyboard, monitor,
modem, mouse, etc.
The Parts of a Computer System - Hardware

11. • Software – also called programs – consists of
organized sets of instructions for controlling the
computer.
• Software is a set of electronic instructions that tells
the computer how to do certain tasks. A set of
instructions is often called a program.
• When a computer is using a particular program, it is
said to be running or executing the program
The Parts of a Computer System - Software

12. • The two most common types of programs are system
software and application software.
----Some programs exist for the computer's use, to help it
manage its own tasks and devices.
----Other programs exist for the user, and enable the
computer to perform tasks for you, such as creating
documents.
Bringing the Machine to Life –
What is Software?

14. • System software exists primarily for the computer
itself, to help the computer perform specific
functions.
• One major type of system software is the operating
system (OS). All computers require an operating
system.
• The OS tells the computer how to interact with the
user and its own devices.
• Common operating systems include Windows, the
Macintosh OS, and UNIX .
Bringing the Machine to Life –
System Software

15. • Application software tells the computer how to
accomplish tasks the user requires, such as creating a
document or editing a graphic image.
• Some important kinds of application software are:
Word processing programs Spreadsheet software
Database management Presentation programs
Graphics programs Networking software
Web design tools and browsers Internet applications
Communications programs Utilities
Entertainment and education Multimedia authoring
Bringing the Machine to Life - Applications

16. • Data consists of raw facts, which the computer can
manipulate and process into information that is
useful to people.
• Computerized data is digital, meaning that it has
been reduced to digits, or numbers. The computer
stores and reads all data as numbers.
• Although computers use data in digital form, they
convert data into forms that people can
understand, such as text, numerals, sounds, and
images.
The Parts of a Computer System - Data

17. Ten different
symbols in
the decimal
system
Numbers above 9
use more than 1 digit

18. • People are the computer's operators, or users.
• Some types of computers can operate without
much intervention from people, but personal
computers are designed specifically for use by
people.
The Parts of a Computer System – Users

19. No computer is totally autonomous.
Human ware refers to the persons who design,program
and operate computer.
The three principal positions for large computer
installations are:
System analyst: The main tasks of a system
analysts is to study information system and
their processing requirements. He or she
defines the application problem, determines
system specifications, recommends the
hardware and software and design.

20. Programmer:
The main requirement of a programmer is the knowledge
of programming language and standard coding
procedures.He or she only code or prepare programs
based on the specification made by the system
analyst.He does not require the broader understanding
of the structure and inner working of the applications.
Operator:
He or she generally performs a series of tasks to keep the
computer operating with maximum efficiency.

21. Characteristics of Computer
• Automatic
• Speed
• Accuracy
• Versatility
• Power of Remembering
• Volume of Data

22. First Generation (1942-1955):
The key features:
o Too balky in size, requires large rooms.
o Thousands of vacuum tubes were used to store data &
instructions.So it produces large heat.
o Vacuuam tubes are unreliable & inefficient in
operations.
o Power consumption is very high. Each tube half a watt.
o Requires constant maintenance.
o Programs were written in machine language.
o Difficult to program and use, had limited commercial
use.
Example: ENIAC(Electronic Numerical Integrator And
Calculator), EDVAC, IBM 701 etc.

23. Second Generation (1955-1964):
The key features:
o Made of semiconductor materials (Transistors).
o More reliable than 1st tube glass.
o Smaller in size and less expensive.
o Less power consumption. One-tenth of tube.
o Less heat produced.
o Faster and large primary and secondary storage
and IO devices.
o Programs are written in machine & assembly
languages.
Example: IBM 7030, CDC 1604 etc.

24. Third Generation (1964-1975):
The key features:
o General purpose machine for scientific and commercial
applications.
o IC technology is used.
o Smaller in size and less expensive than 2nd
generation.
o Less power consumption than 2nd
generation
o Faster and large primary and secondary storage than 2nd
generation.
Example: IBM 360/370, PDP-8, PDP-11 etc.

25. Fourth Generation (1975-1989):
The key features:
o Totally General purpose machine .
o Smaller in size and less expensive than 3rd
generation.
o More powerful and reliable.
o Faster and large primary and secondary storage
than 3rd generation.
o Semiconductor storage devices were introduced.
Example: IBM PC and its clones, Apple II, CRAY-1
etc.

26. Fifth Generation (1989-Present):
The key features:
o Will be capable of reasoning, learning, making
inferences and behaving like human.
o It will be equipped with massive primary storage
capabilities.
o Voice recognition, the ability to understand and obey
spoken words.

27. Classification of Computer
• Supercomputers
• Mainframe Computers
• Minicomputers
• Microcomputers, or Personal Computers

28. • Supercomputers are the most powerful computers and largest
computer used for processing huge amount of data.
• They are used for problems requiring complex calculations.
They are applied to the solution of very complex and
sophisticated scientific problems and for national security
purposes of some advanced nations.
• Because of their size and expense, supercomputers are
relatively rare.
• Supercomputers are used by universities, government
agencies, and large businesses.
• They are generally used in the mapping of human gnome,
forecasting weather etc.
Example: The Cray X-MP
Supercomputers

29. - Mainframe Computers
• Mainframe computers can support hundreds or thousands of
users, handling massive amounts of input, output, and storage.
• Mainframe computers are used in large organizations where
many users need access to shared data and programs.
• They provide greater processing speed,greater and high speed
storage , a larger variety of input/output
devices,multiprogramming and time-sharing.
• Mainframes are also used as e-commerce servers, handling
transactions over the Internet.

30. Minicomputers
• Minicomputers are smaller than mainframes but larger than
microcomputers.
• They are physically smaller,less expensive and have small
storage capacity compared to mainframe.
• They are ideally suited for processing tasks that do not require
access to huge volumes of stored data.
• The capability of a minicomputer are somewhere between
mainframe and microcomputer.
• Some of the larger and expensive minicomputers are capable of
supporting a number of terminals in time-shared mode .

31. Microcomputers, or Personal Computers
• Microcomputers are more commonly known as personal
computers. PC refers to a type of computer system that was
designed for use by a single person.
• Full-size desktop computers are the most common type of PC.
• Notebook (laptop) computers are used by people who need the
power of a desktop system, but also portability.
• Handheld PCs (such as PDAs) lack the power of a desktop or
notebook PC, but offer features for users who need limited
functions and small size.

32. • The brain of microcomputer is the microprocessor;it is a
silicon chip containing necessary circuits to perform
arithmetic/logic operations and to control input/output
operations.
• A microcomputer system is formed by adding I/O
capability and memory to the microprocessor.
• In addition to general-purpose computations,
microcomputers are also used for special purpose
applications in automobiles, airplanes,toys,clocks etc.

34. -CISC vs RISC
• Two major approaches to processor architecture:
• CISC Processor: Complex Instruction Set Computer
• RISC Processor: Reduced Instruction Set Computer
• Example of CISC:
• Intel x86, Motorola 68xxx, and National Semiconductor 32xxx processors, and, to a
lesser degree, the Intel Pentium.
• Example of RISC:
• Freescale/IBM PowerPC, the MIPS architecture, Sun’s SPARC, the ARM, the Atmel
AVR, and the Microchip PIC.
• CISC processors:
• single processing unit
• external memory
• a relatively small register set
• many hundreds of different instructions.
• RISC processors:
• large register sets
• thereby reducing the number of times the processor must access main memory.
• Often-used variables can be left inside the processor, reducing the number of accesses to
(slow) external memory.
• RISC instructions will take only one or two cycles to execute (this depends greatly on the
particular processor). This is in contrast to instructions for a CISC processor, whose instructions
may take many tens of cycles to execute

35. • BIOS
Now that you are familiar with the parts of a PC, let's see what
happens in a typical computer session, from the moment you turn the
computer on until you shut it down:
1. You press the "On" button on the computer and the monitor.
2. You see the BIOS software doing its thing, called the power-on self-
test (POST). On many machines, the BIOS displays text describing
such data as the amount of memory installed in your computer and
the type of hard disk you have. During this boot sequence, the BIOS
does a remarkable amount of work to get your computer ready to run.
• The BIOS determines whether the video card is operational. Most
video cards have a miniature BIOS of their own that initializes the
memory and graphics processor on the card. If they do not, there is
usually video-driver information on another ROM on the motherboard
that the BIOS can load.

36. • The BIOS displays some details about your system. This
typically includes information about the following:
• Processor
• Hard drive
• Memory
• Display
• Any special drivers are loaded from the adapter and the BIOS
displays the information.
• The BIOS looks at the sequence of storage devices identified as
boot devices in the CMOS Setup. "Boot" is short for
"bootstrap," ." Boot refers to the process of launching the
operating system. The BIOS tries to initiate the boot sequence
from the first device using the bootstrap loader.

37. Bootstrap Loader:
The bootstrap loader loads the operating
system into memory and allows it to begin
operation. It does this by setting up the
divisions of memory that hold the operating
system, user information and applications. The
bootstrap loader then establishes the data
structures that are used to communicate within
and between the sub-systems and applications
of the computer. Finally, it turns control of the
computer over to the operating system.

38. You open up a word processing program and
type a letter, save it and then print it out. Several
components work together to make this happen:
• The keyboard and mouse send your input to the operating system.
• The operating system determines that the word-processing program
is the active program and accepts your input as data for that
program.
• The word-processing program determines the format that the data is
in and, via the operating system, stores it temporarily in RAM.
• Each instruction from the word-processing program is sent by the
operating system to the CPU.
• All this time, the operating system is steadily providing display
information to the graphics card, directing what will be displayed on
the monitor.

39. • When you choose to save the letter, the word-processing program
sends a request to the operating system, which then provides a
standard window for selecting where you wish to save the
information and what you want to call it. Once you have chosen the
name and file path, the operating system directs the data from RAM
to the appropriate storage device.
• You click on "Print." The word-processing program sends a
request to the operating system, which translates the data into a
format the printer understands and directs the data from RAM to
the appropriate port for the printer you requested.
• You choose the "Shut Down" option.
• The operating system closes all programs that are currently active.
If a program has unsaved information, you are given an
opportunity to save it before closing the program.
• The operating system writes its current settings to a special
configuration file so that it will boot up next time with the same
settings.
• If the computer provides software control of power, then the
operating system will completely turn off the computer when it
finishes its own shut-down cycle.