itec255 chapter 1
TRANSCRIPT
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ITEC255-ComputerOrganization&Architecture
Eastern Mediterranean University
School of Computing and Technology
ITEC255
Computer Organization
& Architecture
INTRODUCTION
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Introduction
The course is about the structureand functionof computers.
The purpose is to present the nature and characteristics of
modern-day computers.
The intent of this course is to provide:
a detailed discussion of the fundamentals of computer
organization and architecture to relate these to contemporary computer design issues.
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Organization and Architecture
Computer architecturerefers to those attributes of a systemvisible to a programmer or those attributes that have a direct
impact on the logical execution of a program.
Examples of architectural attributes include:
Instruction set
Number of bits used to represent various data types (e.g.
numbers, characters)
I/O mechanisms
Memory addressing techniques
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Computer organizationrefers to the operational units and
their interconnections that realize the architectural
specifications.
Examples of organizational attributes are transparent to
programmer, such as:
Control signals
Interfaces between the computer and peripherals Memory technology being used
Organization and Architecture
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As an example:
The fact that a multiply instruction is available is a
computer architecture issue.
How that multiply is implemented is a computer
organizationissue.
Organization and Architecture
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Many computer manufacturers offer a family of computer
models all with thesame architecture.
All Intel x86 family share the same basic architecture.
The IBM System/370 family share the same basic architecture.
This gives compatibilityfor new models.
Organization differsbetween different versions with changing
technology.
Organization and Architecture
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Structure and Function
Modern computers contain millions of electronic
components.
The key to describe such systems is to recognize their
hierarchical nature.
A hierarchical system is a set of layers or levels of
interrelated subsystems.
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The designer need only deal with a particular level of the
system at a time.
At each level, the system consists of a set of components and
their interrelationships.
The behavior at each level depends only on a simplified,
abstracted characterization of the system at the next lower
level.
Structure and Function
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At each level, the designer is concerned with:
Structure: The way in which components relate to each
other (interrelated).
Function: The operation of each individual components as
part of the structure.
We will usually describe systems from the top-down, instead
of bottom-up.
Structure and Function
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Function
There are only four basic functions that a computer can
perform.1. Data processing: The data may take a wide variety of form,
but only a few fundamental methods or types of data
processing.
2. Data storage: There are long-term or short, temporary storage.
3. Data movement
Input/Output: When data are received from or delivered to
a peripheral, a device connected directly to the computer. Data communication: When data is moved over longer
distances, to or from a remote device.
4. Control:Control of the above functions, by instructions
provided by the user of the computer (i.e. their programs).
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ITEC255-ComputerOrganization&Architecture
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Function
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Within the computer, a control unit manages the computers
resources and orchestrates the performance of its functional
parts in response to those instructions.
Function
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The number of possible operations that can be performed is
four:1. The computer can function as a data movement device,
simply transferring data from one peripheral or
communications line to another.
Function
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2. The computer can function as a data storage device, with
data transferred from external environment to computer
storage (read) and vice versa (write).
Function
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3. The computer can operatedata processing in storage.
Function
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4. The computer can operatedata processing between storage
and external environment.
Function
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Structure
Figure shows thesimplest possible representation of a
computer.
The computer interacts in some fashion with its external
environment.
In general, all of its linkages to the external environment can
be classified as peripheral devices or communication lines.
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There are four main structural components in the internal
structure of the computer:
1. Central processing unit (CPU): Controls the operation
of the computer and performs its data processing
functions. Often simply referred to as processor.
2. Main memory: Stores data.
3. I/O: Moves data between the computer and its external
environment.
4. System interconnection: Some mechanism that provides
communication among CPU, main memory and I/O. A
common example of system interconnection is by means
of asystem bus, consisting of a number of conducting
wires to which all the other components attach.
Structure
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Structure
Internal structure of a computer:
Computer
Main
Memory
I/O
Systems
Bus
Peripherals
Communicationlines
CPU
Computer
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Structure
CPU
Traditionally, there has been just a single processor. In recent
years, there has been increasing use of multiple processors in a
single computer.
Major structural components of CPUare as follows:
Control Unit:Controls the operation of CPU and hence
computer.
Arithmetic and logic unit (ALU):Performs computers
data processing functions.
Registers:Provides storage internal to CPU.
CPU interconnection:Some mechanism that provides
communication among control unit, ALU and registers.
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Internal structure of a CPU:
ALU
Control
Unit
Internal Bus
Registers
CPU
MainMemory
I/O
Systems
Bus
CPU
Structure CPU
Computer
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There are several approaches to the implementation of the
control unit.
The most common is a microprogrammedimplementation.
A microprogrammed control unit operates by executing
microinstructionsthat define the functionality of the control
unit.
Structure
Control Unit
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Control
Memory
Control Unit
Registers
and
Decoders
Sequencing
Logic
Control Unit
ALU
Control
Unit
InternalBus
Registers
CPU
Internal structure of a control unit:
Structure Control Unit
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Why Study Computer Organization and Architecture?
To be a professional in any field of computing today, one
should not regard the computer just as a black box that
executes programs by magic.
Students need to understand computer architecture in order
to structure a program so that it runs more efficiently on a
real machine.