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Computer Architecture

Introduction

IT 321

1st semester 1435/1436

2014/2015

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What computers are?

• Computers are programmable

• They solve problems

• Zeroth GenerationMechanical Computers (1642 – 1945)

• First GenerationVacuum Tubes (1946 – 1959)

• Second GenerationTransistors (1959 – 1965)

• Third GenerationIntegrated Circuits (1965 – 1971)

• Fourth GenerationVery Large Scale Integration (1971 – 1980)

• Fifth GenerationUltra Large Scale Integration (1980 – ?)

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Computer Generations

First Generation

Vacuum Tubes

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First Generation

Vacuum TubesThe main features of First Generation are:

• Supported Machine language only

• Very costly

• Generate lot of heat

• Slow Input/Output device

• Huge size

• Consumed lot of electricity

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Second Generation -

Transistor• Transistor was Invented 1947 at Bell Labs

• Replaced vacuum tubes

• Smaller

• Cheaper

• Less heat dissipation

• more reliable

• Support machine,assmebly and high level

programming language (Fortran,Cobol)

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Third Generation / IC

• Integrated Circuits (IC's) in place of

transistors

• A single IC has many transistors, resistors

and capacitors along with the associated

circuitry.

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Integrated Circuit (IC)

• SSI -several (less than 10) independent gates

• MSI - 10 to 200 gates; Perform elementary digital functions; Decoder, adder, register, parity checker, etc

• LSI - 200 to few thousand gates; Digital subsystem; Processor, memory, etc

• VLSI - Thousands of gates; Digital system; Microprocessor, memory module

• UlSI – millions of gates; ; Digital system; Microprocessor, memory module

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Third Generation / IC

The main features of Third Generation are:

• IC used

• More reliable

• Smaller size

• Generate less heat

• Faster

• Lesser maintenance

• Still costly

• Consumed lesser electricity

• Support high level language

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Third Generation / IC

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PDP 8 by DEC - First Mini computer

Fourth generation - VLSI

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Fourth generation - VLSI

The main features of Fourth Generation are:

• VLSI technology used

• Very cheap

• Portable and reliable

• Very small size

• Pipeline processing

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Fifth Generation

The main features of Fifth Generation are:

• ULSI technolog y

• Advancement in Parallel Processing

• More user friendly interfaces with multimedia features

• Availability of very powerful and compact computers at

cheaper rates

• Some computer types of this generation are: Desktop,

Laptop, NoteBook.

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Fifth Generation

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What computers are?

• Computers are programmable digital

electronic devices.

• They solve problems using algorithms.

• They consist of hierarchical layers of

hardware and software.

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Abstractions

• hardware or software layers are called

abstractions

• abstractions are a way to cope with

complexity

• lower-level details are hidden to offer a

simpler model at higher levels

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Digital Electronic Device

• Computers are programmable digital

electronic devices.

• Electronic device → deals with electrical

signals

• Digital → information is presented by

variables takes a limited number of discrete

values.

• Discrete values are processed internally by

components that contain a limited number of

discrete states.

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Digital System

• Takes a set of discrete information inputs and

discrete internal information (system state) and

generates a set of discrete information outputs.

System State

Discrete

Information

Processing

System

Discrete

Inputs Discrete

Outputs

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Types of Digital Systems

• No state present– Combinational Logic System

– Output = Function(Input)

• State present– State updated at discrete times

=> Synchronous Sequential System

– State updated at any time

=>Asynchronous Sequential System

– State = Function (State, Input)

– Output = Function (State) or Function (State, Input)

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A Digital Computer Example

Synchronous or

Asynchronous?

Inputs:

Keyboard,

mouse, modem,

microphone

Outputs: CRT,

LCD, modem,

speakers

Memory

Controlunit

Datapath

Input/Output

CPU

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Signal• An information variable represented by physical

quantity.

• For digital systems, the variable takes on discrete values.

• Two level, or binary values are the most prevalent values in digital systems.

• Binary values are represented abstractly by:– digits 0 and 1

– words (symbols) False (F) and True (T)

– words (symbols) Low (L) and High (H)

– and words On and Off.

• Binary values are represented by values or ranges of values of physical quantities

Course Outcomes

• Define major components and their interactions

in computer architecture.

• Apply Boolean algebra , Karnaugh Maps. and

Symbolic Logic to Circuit Analysis and Design.

• Analyze digital Circuits.

• Design digital Circuits.

• Describe basic memory systems.

• Design the data path of a computer.

• Design a simple instruction set computer with

hardwired control unit.

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