1 Introduction to Information Technology LECTURE 11: INTRODUCTION TO COMPUTER ARCHITECTURE AND SOFTWARE IT 101 Section 3 Department of Electrical and Computer.

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Introduction to Information Technology

LECTURE 11: INTRODUCTION TO COMPUTER ARCHITECTURE AND SOFTWARE

IT 101 Section 3Department of Electrical and Computer Engineering

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Introduction to Computer Architecture

Knowledge of some computer history milestones Basic understanding of computer hardware and software Understanding of basic hardware elements in a desktop computer:

CPU Memory Storage Input/Output

Understanding of the hierarchy of computer software Applications Computer languages Operating systems Assembly code and machine language

Apple Mac1984

IBM PC1981

GOALS

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Calculating Machines Through History

The Abacus 5000 years old Addition and subtraction

Mechanical Calculators Charles Babbage’s mechanical calculators

prefigured modern computers Electronic “Calculators”

Vacuum Tubes Transistors

Modern Computer Microprocessors

Charles Babbage’sDifference Machine(Picture courtesy of Science Museum/Science & Society Picture Library)

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ENIAC

What were computers like just over 50 years ago? 1946 - ENIAC Used plugboards and switches to program Used vacuum tubes Developed at UPenn Funded by U.S. government

ENIAC

Electronic Numerical Integrator and Computer

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Computer Generations

Vacuum Tubes 1946-1957

Transistors1958-1964

Small Scale Integration: 1960sUp to 100 devices per chip

Medium Scale Integration: Pre-1971100-3000 devices per chip

Large Scale Integration: 1971-773000- 100,000 devices per chip

Very Large Scale Integration: Post 1978100,000 - 100 million devices per chip

Ultra Large Scale Integration> 100 million devices per chip

INTEGRATED CIRCUIT

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Moore’s Law

Intel pioneer, Gordon Moore, predicted in 1965 that the number of transistors on a chip would double every 18 months.

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Some Computer Hardware

Inside the Computer CPU, Memory Chips Floppy drive, Hard disk, CD-

ROM, DVD Player Motherboard, Expansion Slots,

Power Supply Back of Computer

Cooling Fan, Power Connector Keyboard and Mouse

Connectors Parallel Printer Port Video Connector

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Desktop Computer Hardware

Four main functional units of a computer Central Processing Unit (CPU) Memory Storage Input/Output

Input/OutputCentral Processing

Unit

Storage

Memory

From the optional textbook, The Digital Information Age

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Central Processing Unit - CPU

The Microprocessor The brains, or main processing unit, of the computer Performs calculations and completes instructions Performance based on clock speed Pentium 4 -- 2.8 GHz chip operates at 2.8 billion cycles

per second

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Four Stages of CPU Operation Fetch - Seeks instructions from outside source Decode - Analyzes the instructions to determine which of the chip’s circuits should be used for processing Execute - Performs the actual instructions Store - Places processing result in appropriate place

Comparing a Dime to a Microprocessor

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The CPU

Input/Output

Storage Memory

CacheMemory

ArithmeticLogical

Unit(ALU)

Flags

Registers

ControlUnit

Execution of instructions occurs here.Grouping of transistors (logic gates) that perform logical and mathematical functions

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Memory

RAM – Random Access Memory Can read or write data E.g. cache memory (on the CPU) Measured in MegaBytes (MB) Volatile memory: erased when computer powered

off

ROM – Read only memory Permanently stored information used repeatedly

by computer Can never accept new information Normally installed by system manufacturer Non-volatile

Computers require storage in order to process information.

TWO TYPES OF COMPUTER MEMORY

Temporary

Long-Term

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Storage

Provides long-term retention of data on magnetic or optical disk

Hard Drive Disc capacity currently measured in GigaBytes (GB)

Floppy Disc Typical capacity of 1.44 MegaBytes (MB)

Compact Disc 650 MB

Zip Drive Removable floppy discs that store up to 250 MB

DVD Optical storage

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Input/Output devices

Input Devices - Accepts data from external sources and converts to electric signal

Keyboard, Mouse, Touch screen, Voice activation, Video Camera, Microphone, Scanner, JoyStick

Output Devices - Accepts electric signals from CPU and converts them to an output device.

Monitor Printer Speakers Communication ports

Moves data between the computer and its external environment.

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Input/Output

CPU

Sound Board

bus

Game Board

Graphics Board

Serial Port

Parallel Port

Serial Port

Network Port

ADC

input/output

Mode

Monitor

Local Area Network

Analog signal source

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Computer Software

Software consists of instructions and application programs that permit computers to accomplish tasks.

It is called software because, unlike hardware that has fixed configurations, connections, and operation, software is flexible and easily modified.

Operating System

Assembly Code

Programming Language(High Level Language)

Applications

Hierarchy of Software

Machine Language

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Machine Language

01100100100101010 Lowest level language Consists of elementary

instructions directly recognized by the CPU

Provides numerical codes directly recognized by the CPU

Machine language programming produces a string of numbers

Not commonly used anymore

Operating System

Assembly Code

Programming Language(High Level Language)

Application

Hierarchy of SoftwareHow does it relate to “Assembly Language?”

Machine Language

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Assembly Code

Also called Assembly Language Also consists of elementary

instructions directly recognized by the CPU, but uses codes rather than numbers.

Assembly code is different for every type of computer. (i.e. it is CPU specific)

Cumbersome to develop. Difficult to later read and

modify An “assembler” converts

assembly language to machine language.

Operating System

Assembly Code

Programming Language(High Level Language)

Application

Hierarchy of Software

Machine Language

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Operating System Computer program that links

various hardware components to one another

Stored on hard disk Loaded to memory when the

computer is turned on Once in memory, the

operating system takes over and manages the system

Provides a user interface Manages memory Controls directory access Supports hardware Supports applications

Examples of O/S?

Hierarchy of Software

Operating System

Assembly Code

Programming Language(High Level Language)

Application

Machine Language

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Examples of Operating Systems

MS-DOSIntroduced in 1981Microsoft’s first O/S

Microsoft Disk Operating System (MS-DOS)

Text based O/S -- C:/>

Mac OSAppeared in 1984 Apple Macintosh

Icons and Graphical User Interface (GUI)

Microsoft WindowsDominates PC marketWindows 3.x in 1990Windows 95 and 98

Windows NTWindows 2000

Windows XP

IBM OS/2Roughly 1992

Split with Microsoft Never took off

Unix VariationsIBM’s AIX

Hewlett Packard’s HP/UXSun’s Solaris

LinuxOthers

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The Linux Operating System

Linus Torvalds developed Linux in 1991. Linux’s open source code is freely available on the web. Most software is in a compiled, computer-readable, ready-to-run format that conceals how the software was developed. Open source code is source code that anyone can view/modify. Linux is a competitor to Windows NT/2000, especially in the business “server space.” Other software based on open source code includes the Apache web server and PERL, a web scripting language. What are the advantages and disadvantages of open source code?

What’s different about Linux? Why do we hear so much about this?

Key Concept: Open Source Code

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Programming Languages

A computer program tells a computer what to do.

Needs to be written in a programming language the computer can understand.

A “compiler” translates almost

human syntax into lower level code the computer can “execute.”

Theoretically no longer CPU-specific like assembly code.

What are some examples of programming languages?

Operating System

Assembly Code

Programming Language(High Level Language)

Application

Hierarchy of Software

Machine Language

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Programming Language Evolution

FORTRAN(Formula

Translator)Developed by IBM

Science/engineering

1957

COBOL(Common

Business Oriented Language)

Pushed by U.S. Govt.1960

Installed base of code in COBOL

still considerable

Basic(Dartmouth

College,Kemeny and Kurz)Simple language students could

learn1964

PascalOnce popular with

serious programmers

1970s

Appeal has diminished

C and C++Developed

originally as C/Unix in

1974C++ is object

oriented version

Visual BasicMicrosoft’s

“visual language”Provides an array

of tools that decrease

development time

HTMLHyperText Markup

Languagedescribes

documents on the Web

XMLeXtensible Markup

LanguageMore powerful

successor to HTML

JavaDeveloped by SunO/S independent

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Key Programming Terms

Programming is telling the computer what to do. Source Code is a series of commands written in a

programming language. Programming languages are sometimes divided into 4

categories: 1GL (first generation language) - Machine language 2GL (second generation language) - Assembly language 3GL (third generation languages) - Cobol, Pascal, C, Basic 4GL (fourth generation languages) - vague, diverse term

that includes object oriented programming languages, visual languages, and markup languages.

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Application Software

Program at the command of the user. Application programs can be

downloaded from web sites or installed from a CD-ROM. They install almost automatically.

Microsoft Office MS Word – word processing MS Excel – spreadsheet program MS PowerPoint – presentations MS Access 2000 – DBMS (database

management system) AOL Instant Messenger Voice Recognition Software Oracle DBMS Netscape Navigator

“Shrink-wrapped software” available at the store

Operating System

Assembly Code

Programming Language(High Level Language)

Application

Hierarchy of Software

Machine Language

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Recommended Optional Excursion

“Information Age” Exhibit at The Smithsonian’s American History Museum

Chronicles the birth and evolution of information technology

Contains many famous information technology artifacts: Samuel Morse’s telegraphs Alexander Bell’s telephones A Hollerith punched card machine The ENIAC computer Early personal computers