ECCS 3212 Chapter_1_COA part 1.pptx

Computer Science & Engineering
 Course Name: Computer Organization &
Architecture
1

CHAPTER:1
Introduction computer organization and
design logic
OUTLINE
 Introduction to computer Organization
and Architecture
 Computer Components
 Structure and Function
 Interconnection Structure
 Bus Interconnection
2
ECCS 3212 : Computer Organization and Architecture

Introduction
What is a computer ?
 A computer is an electronic device that
can accept, store and process data under
the control of a set of instructions.
 A computer is a machine that can
perform computation. It is difficult to
give a precise definition of computation.
3

What is a digital computer?
 A digital computer accepts input, processes
and outputs data in digitized forms (as
opposed to analog forms) and stores the
result for later use.
 Computers are programmable, i.e., one
can solve one's own problems by a
computer.
4

Computer Organization and Architecture
 Computer Organization and Architecture is the
study of internal working, structuring and
implementation of a computer system.
Architecture in computer system, refers to the
externally visual attributes of the system.
 Organization of computer system is the way of
practical implementation which results in
realization of architectural specifications of a
computer system.
 Organization will be the way the system is
structured 5

 Computer architecture refers to those
attributes of a system visible to a
programmer.
Instruction set, number of bits used for data
representation, I/O mechanisms, addressing
techniques.
 e.g. Is there a multiply instruction?
Definitions

Cont…
 Computer organization refers to the
operational units and their interconnections
that realize the architectural specifications.
 Organization is how features are
implemented
 Control signals, interfaces, memory
technology.
 e.g. Is there a hardware multiply unit or is
it done by repeated addition? 7

Computer Components
Block
diagram
of
a
digital
computer
Processor Unit
(ALU)
Storage, or
Memory Unit
Input
Devices
and
Control
Output
Devices
and
Control
Control Unit
8

There are four main structural components:
 Central processing unit (CPU): Controls the
operation of the computer and performs its
data processing functions; often simply
referred to as processor.
 Supervises the flow of information between
the various units
9
Computer Components

 It retrieves the instructions, one by one, from
the program that is stored in the memory
 For each instruction, the control unit informs
the processor to execute the operation
specified by the instructions & the processor
manipulates the data as specified by the
program.
10

 Memory unit: Stores program as well as
input, output, and the intermediate data.
 System interconnection: Some mechanism
that provides for communication among
CPU, main memory, and I/O.
 Input /Ouput (I/O) unit: Moves data
between the computer and its external
environment.
11

 The program and data prepared by the
user are transferred into the memory unit
by means of an input device such as a
keyboard.
 An output device, such as a printer, re-
ceives the result of the computations and
the printed results are presented to the
user.
12

Structure & Function
 Structure is the way in which components
relate to each other
 Function is the operation of individual
components as part of the structure
13

Cont…
 The input and output devices are special
digital systems driven by electromechanical
parts and controlled by electronic digital
circuits.
14

Function
All computer functions are:
 Data processing
 Data storage
 Data movement
 Control
15

 The data may take a wide variety of forms,
and the range of processing requirements is
broad.
Store Data.
 Even if the computer is processing data on
the fly (i.e., data come in and get processed,
and the results go out immediately), the
computer must temporarily store at least
those pieces of data.
16
Process Data

Move Data
 Between itself and the outside world.
 The computer’s operating environment
consists of devices that serve as either
sources or destinations of data
17

Control
 A control unit manages the computer’s
resources and orchestrates the
performance of its functional parts in
response to those instructions
18

Interconnection Structures
 A computer consists of a set of components
(CPU,memory,I/O) that communicate with
each other.
 The collection of paths connecting the
various modules is call the interconnection
structure.
19

Cont…
 The design of this structure will depend on the
exchange that must be made between modules.
 All the units must be connected
 Different type of connection for different type
of unit
 Memory
 Input/Output
 CPU
20

Computer Modules
21
Memory Connection
 Receives and sends data
 Receives addresses (of
locations)
 Receives control signals
 Read
 Write
 Timing

Input/Output Connection(1)
 Similar to memory from computer’s
viewpoint
 Output
 Receive data from computer
 Send data to peripheral
22

Cont…
 Input
 Receive data from peripheral
 Send data to computer
 Receive control signals from computer send
control signals to peripherals
 e.g. spin disk
23

Input/Output Connection(2)
 Receive addresses from computer
 e.g. port number to identify peripheral
 Send interrupt signals (control)
CPU Connection
 Reads instruction and data
 Writes out data (after processing)
 Sends control signals to other units
 Receives (& acts on) interrupts
24

Type of transfers
 Memory to CPU
 CPU to Memory
 I/O to CPU
 CPU to I/O
 I/O to or from Memory (DMA)
25

Bus Interconnection
 A bus is a communication pathway connecting
two or more device.
 A key characteristic of a bus is that it is a shared
transmission medium.
 A bus consists of multiple pathways or lines.
 Each line is capable of transmitting signal
representing binary digit (1 or 0)
26

The bus interconnection diagram
27

Bus Interconnection
 A sequence of bits can be transmit across a single
line.
 Several lines can be used to transmit bits
simultaneously (in parallel).
 A bus that connects major components
(CPU,Memory,I/O) is called System Bus.
 The most common computer interconnection
structures are based on the use of one or more
system buses.
28

Bus Structure
 A system bus consists of 50-100 lines.
 Each line is assigned a particular meaning or
function.
 On any bus the lines can be classified into 3
groups
 Data lines
 Address lines
 Control lines
29

Data Lines
 Provide a path for moving data between system
modules.
 These lines, collectively, are called the data bus
 The data bus typically consists of 8,16 or 32
separate lines, the numbers of lines being
transferred to as the width of the data bus.
 Each line carry only 1 bit at a time, the number of
lines determines how many bits can transferred at
a time - overall system performance.
30

The Address Lines
 Used to designate the source or destination of the
data on the data bus
 The width of the address bus determines the
maximum possible memory capacity of the
system.
31

The Control Lines
 Used to control the access to and the use of the data
and address lines.
 Typical control lines include
 Memory write
 Memory read
 I/O write
 I/O read
 Clock
 Reset
 Bus request
 Bus grant
 Interrupt request
 Interrupt ACK
 Transfer ACK
32

 Memory write: Causes data on the bus to be written
into the addressed location
 Memory read: Causes data from the addressed location
to be placed on the bus
 I/O write: Causes data on the bus to be output to the
addressed I/O port
 I/O read: Causes data from the addressed I/O port to be
placed on the bus
33

 Transfer ACK: Indicates that data have been
accepted from or placed on the bus
 Bus request: Indicates that a module needs to
gain control of the bus
 Bus grant: Indicates that a requesting module
has been granted control of the bus
 Interrupt request: Indicates that an interrupt
is pending
34

 Interrupt ACK: Acknowledges that the pending
interrupt has been recognized
 Clock: Is used to synchronize operations
 Reset: Initializes all modules
35

The operation of the bus
If one module wishes to send data
 obtain the use of the bus
 transfer data via the bus
If one module wishes to request data
 obtain the use of the bus
 transfer request to the other module over the
control and address lines, then wait for that
second module to send the data.
36

Physical Bus Architecture
 System bus is a number of parallel electrical
conductors.
 The conductors are metal lines attched in a card or
printed circuit board.
 The bus extends across all of the components that
taps into the bus lines.
37

38

Single Bus Problems
 Lots of devices on one bus leads to:
 Propagation delays
 Long data paths mean that co-ordination of
bus use can adversely affect performance
 If aggregate data transfer approaches bus
capacity
 The solution are : Using multiple buses to
overcome the problems.
39

Bus Design
 Type
 Dedicated
 Multiplexed
 Bus Width
 Address
 Data
 Timing
 Synchronous
 Asynchronous
 Method of Arbitration
 Centralized
 Distributed
 Data Transfer Type
 Read
 Write
 Read-modify-write
 Read-after-write
 Block
40

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