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IT321-Introduction1
Computer Architecture
Introduction
IT 321
1st semester 1435/1436
2014/2015
IT321-Introduction2
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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