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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

GOALS

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ENIAC

What were computers like just over 50 years ago?

ENIAC

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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

http://nobelprize.org/physics/educational/integrated_circuit/index.html

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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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Components of the CPU

Arithmetic and Logic Unit (ALU): processes the data in the registers according to instructions issued by the control unit. Performs arithmetic (addition, subtraction, etc..) and logical (comparison) operations

Registers: provides temporary storage for data and instructions. It handles instructions and data at 10 times the speed of cache memory. Registers facilitate the movement of data and instructions between RAM, the control unit and the ALU

Internal CPU interconnection: some mechanism that provides for communication among the different components of the CPU

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Control Unit: controls the operation of the CPU and hence the computer. Interprets instructions, moves data to/from memory and registers, instructs ALU to perform certain operations, etc. During program execution, instructions in a program are moved from the RAM into the control unit, where it is decoded and interpreted by the decoder

Flags: 1-bit memory, or 1-bit registers and hold information on what has recently happened in the CPU. These are set to 1 or 0 depending on the results of internal operations such as results of ALU operations (zero or negative result) or external operations such as interrupts (commands that tell the processor to stop execution and wait for further instruction)

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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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Main (Internal) Memory

RAM – Random Access Memory. Temporary read/write memory. Applications are typically loaded into RAM during computer use. Types of RAM include:

SRAM (static) and DRAM (dynamic ) SRAM is called static because the memory retains its

contents as long as power is supplied -- It does not have to be periodically refreshed as in DRAM. It is faster than DRAM (The contents of the memory can be read much faster), however is more expensive and is larger in size

DRAM is called Dynamic RAM because the memory content needs to be refreshed periodically (every few milliseconds) due to leakage of electrical charge. It is slower than SRAM, but cheaper and smaller in size

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

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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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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

Operating System

Assembly Code

Programming Language(High Level Language)

Application

Hierarchy of Software

Machine Language