I1100Introduction to Computer Science

Semester: 1 Academic Year: 2015/2016

Credits: 3 (30 hours)Dr. Antoun Yaacoub

Lebanese UniversityFaculty of Sciences

Computer Science BS Degree

I1100- Introduction to Computer ScienceSchedule

Monday Tuesday Wednesday Thursday Friday

08h00-09h40 I1100

09h50-11h30

11h50-13h30 I11001 week over 2

14h00-15h40

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I1100- Introduction to Computer ScienceGrading

Mid-term exam 30 pts

Final Exam 70 pts

Total 100 pts

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Dr. Antoun Yaacoub

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Office 3rd floorDean’s Office

Office 304

Email antoun.yaacoub@ul.edu.lb

Web site www.antoun.mewww.fsciences.ul.edu.lb/antoun.yaacoub

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Aim• Introducing fundamental topics in Informatics

• Developing a basic understanding of Information Theory

• Emphasizing its use in the modeling of nature and technology

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Syllabus1. Introduction to Computer Science

2. Computer architecture

3. Operating system

4. Software

5. Databases

6. Introduction to networks

7. Internet

8. Computer Science and Society

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Introduction to Computer Science1 lecture

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Introduction to Computer ScienceOutline of this lecture1. Definitions

a. Turing Model

b. Von Neumann Model

2. Computer Components

a. Hardware

b. Data

c. Software

3. History

a. Mechanical Machines (before 1930)

b. The birth of electronic computers (1930-1950)

c. Computer Generations (1950-present)

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Definitions• Computer Science = Computing Science = Informatics

• Informatics = information + automatic

• Informatics = automation of information treatment by a system

• Computer = Computational device

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Example of a computational device• Show the steps that your perform if you want

the result of the sum between 2 and 3.

• Press on 2 (input the data 2)

• Press on + (compute the sum operation)

• Press on 3 (input the data 3)

• Press on = (output the final result)

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Data Processor• Computer = Data processor ?

• Computer acts as a black box that1. accepts input data,

2. process the data

3. and creates output data.

• This model is too general, in the sense that a pocket calculator becomes also a computer !

• What if we need to compute 6 ∗ 𝑒5 − (20! +𝜋

4) ?

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ComputerInput data Output data

Turing Model Universal computational device introduced by Alain

Turing in 1937.

The Turing model is a better model for a general-purpose model.

It adds an extra element: the program

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Turing Model

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PROGRAM

a sequence of instructions that

tells the computer what to do with

data

Turing Model• In the Turing model, the output data depends on the combination of two

factors: the input data and the program.

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ComputerInput data Output data

Program

Turing Model

• With the same input data, we can generate different outputs if we change the program.

• With the same program, we can generate different outputs if we change the input data.

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ComputerInput data Output data

Program

Examples

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Computer3, 12, 8, 22Input data

3, 8, 12, 22Output data

SortProgram

Computer14, 6, 8, 12Input data

6, 8, 12, 14Output data

SortProgram

Examples

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Computer3, 12, 8, 22Input data

3, 8, 12, 22Output data

SortProgram

Computer3, 12, 8, 22Input data

45Output data

AddProgram

Computer3, 12, 8, 22Input data

3Output data

Find SmallestProgram

Turing Model• Universal Turing Machine = machine that can do any

computation if the appropriate program is provided

• Universal Turing Machine = capable of computing anything that is computable

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Von Neumann Model

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Input data Output data

Program

• John Von Neumann proposed that programs should also be stored in the memory of a computer.

Computer

Four Subsystems• Computers built on the Von Neumann model divide the computer hardware

into four subsystems:

Memory

Arithmetic logic unit

Control unit

Input/output

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Computer

Inputdata

Outputdata

Input/output

Memory

Arithmetic Logic Unit (ALU)

Control Unit

Four SubsystemsMemory

• Memory is the storage area.

• This is where programs and data are stored during processing.

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Four SubsystemsArithmetic Logic Unit (ALU)

• ALU is where calculation operation take place.

• For a computer to act as a data processor, it must be able to do:

a. Arithmetic operations on data

b. Logical operations on data

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Four SubsystemsControl Unit

• The control unit controls the operations of the

memory,

ALU,

and the input/output subsystem.

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Four SubsystemsInput / Output

• The input subsystem accepts input data from outside the computer.

• The output subsystem sends the results of processing to the outside world.

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Programs in Von Neumann Model

• A program is made of a finite number of instructions.

• Instructions are executed one after another.

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Computer Components• A computer is made up of three components:

a. Computer hardware

b. Data

c. Computer software

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Computer ComponentsHardware

• Computer hardware has 4 basic components under the Von Neumann model.

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Computer ComponentsData

• Different types of data:

numbers,

text,

image,

video,

audio

…

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Computer ComponentsSoftware

• Programs are stored in the computer’s memory.

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Program

Data

Memory

Computer ComponentsSoftware

• Programs consist of a sequence of instructions.

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Program

1. Input the first number into memory

2. Input the second number into memory

3.Add the two together and store the result in memory

4.Output the result

Computer ComponentsSoftware• A program must be composed of instructions for

reusability.

• A programmer can combine instructions to make any number of programs.

• Each program can be a different combination of different instructions.

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Computer ComponentsAlgorithms• A programmer must learn how to combine instructions to

do a particular task.

• A programmer must first solve the problem in a step-by-step manner, then try to find the appropriate instruction (or series of instructions) to implement those steps.

• Step-by-step solution = Algorithm

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Computer History Timeline

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Mechanical Machines

(before 1930)

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352400 BC Abacus

• One of the world’s oldest computing device.

• The device uses beads attached to wires in a frame to represent units, tens and thousands.

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361642 Pascaline

• Blaise Pascale invents the “Pascaline”, a mechanical adding machine

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371671 Leibnitz Wheel

• Gottfried Leibnitz invented a more sophisticated mechanical calculator that could do multiplication and division as well as addition and substraction.

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381801 Jacquard loom

• The first machine that used the idea of storage and programming.

• Uses punched cards like a stored program.

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391823 First Mechanical Computer

• Charles Babbage invented the Difference Engine, which can do more than simple arithmetic operations.

• It could solve polynomial equations.

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401837 Analytical Engine

• Charles Babbage invented the Analytical Engine.

• 4 components: a mill (modern ALU), a store (memory), an operator (control unit), and output (input/output)

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411890 First Counting Machine

• Herman Hollerith built a programmable machine that could automatically read, count and sort data

Birth of electronic computers

(1930-1950)

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•Early computers in this period did not store the program in memory.

•Five computers were prominent during these years

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441938 Z1

• Konrad Zusedesigned a general purpose machine using punch tape

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451939 ABC

• Called ABC (Atanasoff Berry Computer)

• Designed to solve a system of linear equations

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461943 Colossus

• Invented by Alan Turing

• Designed to break the German Enigma code

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471944 Mark 1

• Huge computer sponsored by US Navy and IBM at Harvard University.

• Uses both electrical and mechanical components.

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481946 ENIAC

• First totally electronic computer.

• Called ENIAC (Electronic Numerical Integrator And Calculator).

• Weighted 30 tons

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491950 EDVAC

• First computer based on Von Neumann’s model.

• Called EDVAC (Electronic Discrete Variable Automatic Computer).

Computer recent 5 generations

(1950-present)

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•Computers follow the Von Neumann model.

•Become faster, smaller and cheaper.

•5 generations with each witnessing major changes in hardware or software.

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521950 – 1959 First Generation

• Emergence of commercial computers.

• Used by professionals.

• Affordable only by big companies.

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531959 – 1965 Second Generation

• Size and cost reduced

• Affordable for small organizations

• FORTRAN and COBOL (programming languages) invented and made programming easier.

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541965 – 1975 Third Generation

• Invention of integrated circuit (transistors, wiring and other components on a single chip).

• Minicomputers appeared on the market.

• Software packages became available.

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551975 – 1985 Fourth Generation

• Microcomputers appeared on the market.

• Computer networks appeared.

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56From 1985 Fifth Generation

• Appearance of laptops, pads, palmtop computers.

• Improvements in storage media: CD-ROM, DVD, …

• Usage of multimedia

• Virtual reality

Application Domain

• Finance (stock exchange, banks, ...)

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Application Domain

• Production (robotics, management, ...)

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Application Domain

• Science (weather forecast, geography, physics, mathematics, medicine, pharmacy, genetics,… )

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Application Domain

• Network Supervision (electricity, oil, transport, ...)

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Application Domain

• Avionics, Automotive, …

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References• Foundations of Computer Science

Behrouz A. Forouzan, Firouz Mosharraf

• http://wallblog.co.uk/files/2012/06/History-of-Computers.jpg

• http://www.datesandevents.org/events-timelines/07-computer-history-timeline.htm

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