2. WHAT IS COMPUTER??????
A computer is a device that accepts
information (in the form of digitalized
data) and manipulates it for some result
based on a program or sequence of
instructions on how the data is to be
processed.
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3. COMPUTER ARCHITECTURE
• Concerned with the way the hardware
components operate and the way they are
connected together to form the computer
system.
• The various components are assumed to be in
the place and the task is to investigate the
organizational structure to verify that the
computer parts operate as intended.
4. COMPUTER ORGANISATION
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• Concern the way hardware components operate and
the way they are connected together to form the
computer system.
• Concerned with the structure and behavior of the
computer as seen by the user. It includes the
information format, the instruction set and techniques
for addressing memory.
• The architectural design of a computer system is
concerned with the specifications of the various
functional modules, such as processors and
memories and structuring them together into a
computer system.
5. 3
is about component that linked with
operational unit of a computer
system
Example : hardware technology,
interface, memory technology and
control signal.
organisation may change as rapid
changes of technology
is about attributes in computer
system as viewed by programmer
and have a direct impact to logic
execution of a program.
Example : instruction set, arithmetic,
addressing modes and input output
mechanisme.
architecture may maintained for hundred
years
one computer model, for example Intel
x86; may maintained its architecture but
differ in its organisation
Computer OrganisationComputer Architecture
10. • provide instruction or data to the system
• In order for a computer to receive the
requests and instructions of the user,
some methods of inputting data and
information to the computer are required.
Input devices
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11. • Needs to display the result to the user
• to communicate with the user and display
information that is being worked on, output
device is required
Output devices
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12. Memory/main memory
• Used to store instruction or data
• Operation on data requires access for more than one
time, so data and instruction have to be stored
temporarily
External storage
• backing store or secondary memory, allows the
permanent storage of large quantities of data
storage
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13. • the central brain of the PC
• Referred as central processing unit(CPU)
• majority of the operations of the computer
are handled by the processor
• contains ALU, registers and control unit
processing
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15. • Arithmetic and Logic Unit (ALU)
- where arithmetic and Boolean logical calculations
are performed (arithmetic, logic and comparison)
• Control Unit
- controls the flow of information through the
processor, and coordinates the activities of the
other units within it
• Central Processing Unit(CPU)
- brain of any computer system
- execute programs stored in the main memory by
fetching, examining and executing instruction one
after another
How ALU,CU and CPU control the
operation of computer????
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Basic
computer
functional
unit
16. • Propose byPropose by John Von NeumannJohn Von Neumann
• Apply stored- program conceptstored- program concept
– Stored-program concept- data and program storedStored-program concept- data and program stored
in the same memoryin the same memory
• Von Neumann architecture based on 3 key concept:
Data and instruction are stored in a single read-
write memory
Content of the memory are addressable by location,
without regards to the type of data contained there
Execution occurs in a sequential fashion(from one
instruction to the next)
VON NEUMANN MACHINE
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18. VON NEUMANN MACHINE
It consists of
A main memorymain memory which stores both data
and instruction
An arithmetic and logic unit(ALU)arithmetic and logic unit(ALU) capable
of operating on binary data
A control unitcontrol unit, which interprets the
instruction in memory and causes them to
be executed
Input output(I/O)Input output(I/O) equipment operated by
control unit
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19. • Is a communication pathway connecting major computer
components such as CPU, memory and I/O unit
System Bus(internal bus)
Bus Interconnection Scheme
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20. • A data bus simply carries data.
• Internal buses carry information within the
processor, while
• External buses carry data between the
processor and the memory.
• Typically, the same data bus is used for
both read/write operations.
DATA BUS/LINES
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21. • A path for moving data between system
modules
• Data bus consist of 32 to hundreds lines,
lines referred as width of data bus
• Width of data bus determine the overall
system’s performance
DATA BUS/LINES
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22. • Used to indicate the source or destination of
data on the data bus
• e.g. CPU needs to read a word of data from
memory, it puts the address of desired word on
the address line
Bus width determines maximum memory
capacity of system(number of address locations
that can be accessed)
ADDRESS BUS
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23. • Microprocessor uses control bus to
process data, that is what to do with the
selected memory location.
• Some control signals are Read, Write and
Opcode fetch etc.
CONTROL BUS/LINES
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24. • Control the access and the uses of data
and address line. Provide timing
information
– Memory read/write signal
– Interrupt request
– Clock signals
CONTROL BUS/LINES
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25. LOCAL BUS
BUS SPEED COMPARISON
Bus
type
Width
(bits)
Speed
(MHz)
Total Data
Rate (MB/Sec)
ISA
EISA
VL-bus
VL-bus
PCI
PCI
PCIe
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32
32
32
32
64
Serial
8
8
25
33
33
33
16
32
100
132
132
264
250 per lane
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26. Peripheral Bus
(external/expansion bus)
• Electronic pathways that connects the
different external devices, peripherals,
expansion slots, I/O ports and drive
connections to the rest of the computer
• allows various devices to be added to the
computer(computer capacities increased)
• Slower than internal bus
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27. Types of external busesTypes of external buses
ISA
Introduced by IBM, ISA or Industry Standard
Architecture
originally an 8-bit bus and later expanded to a 16-bit
bus
still in use because it's cheap and for backwards
compatibility
16bit ISA Card
16bit ISA Slot
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29. USB (Universal Serial Bus)
most popular form of bus use today
USB is hot swappable
USB can daisy chain up to 127 devices
USB Speeds
USB 1.0 supports 1.5Mbps
USB 1.1 supports 12Mbps
USB 2.0 supports up to 480Mbps
USB 3.0 supports up to 4.8Gbps
USB A
Connector
USB B Connector
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30. AGP (Advanced Graphic Port)
Introduced by Intel in 1997
32-bit bus or 64-bit bus designed for the high
demands of 3-D graphics
has a direct line to the computers memory
which allows 3-D elements to be stored in the
system memory instead of the video memory
fastest expansion bus in use but its only for
video or graphics environment
AGP Card
AGP Slot
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32. Cache MemoryCache Memory
Cache memory, is a fast RAM system designed to
hold data recently accessed from the disk drive that
the microprocessor may need again.
The cache contains a copy portion of the main
memory
When the processor attempts to read a word of
memory , a check is made to determine if the word
is in cache. If so the word is delivered to processor.
If not a block of main memory is read into cache
and the required word is transferred to processor
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34. Address/ cache mappingAddress/ cache mapping
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- Is the way to map/place main memory blocks
into cache slots
Commonly used methods:
Associative Mapped Cache
Direct-Mapped Cache
Set-Associative Mapped Cache
38. Address mappingAddress mapping
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Associative
- No restriction on mapping from M to C.”
Associative search of tags is expensive.
Feasible for very small size caches only.
- overcome the disadvantages of the
direct mapped by permitting each main
memory block to be loaded into any line
of cache
42. Input /Output in computerInput /Output in computer
systemsystem
an element of computer system
composed of two parts
oInput unit-providing input to processor
oOutput unit-receiving output from processor
Provide interaction with outside world
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44. Input and Output DevicesInput and Output Devices
Input devices
-human data entry devices and source entry devices
-human entry devices(keyboard, mouse, joystick, digitizing
tablet,..)
-source entry devices(microphone, soundcard, video camera,…)
Output devices
-hardcopy and softcopy devices
-hardcopy devices(printer, plotter)
-softcopy devices(monitor, visual display terminal, video output,…)
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45. Input/output module(interface)Input/output module(interface)
Provides a method for transferring information between internal
storage (such as memory and CPU registers) and external I/O
devices
Resolves the differences between the computer and peripheral
devices
1) Peripherals - Electromechanical Devices
CPU or Memory - Electronic Device
2) Data Transfer Rate
»Peripherals - Usually slower
»CPU or Memory - Usually faster than peripherals
3) Unit of Information
»Peripherals – Byte, Block, …
»CPU or Memory – Word
So, some kinds of Synchronization mechanism may be needed
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49. I/O StepsI/O Steps
•CPU checks I/O module device status
•I/O module returns status
•If ready, CPU requests data transfer
•I/O module gets data from device
•I/O module transfers data to CPU
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51. Programmed I/OProgrammed I/O
•CPU has direct control over I/O
–Sensing status
–Read/write commands
–Transferring data
•CPU waits for I/O module to complete
operation
•Waste the CPU time
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53. Interrupt-Driven I/OInterrupt-Driven I/O
able to overcome programmed I/O
disadvantages
CPU have to wait for a long time for I/O
module
CPU issue an I/O command to a module and
will go on to do other useful work. I/O will
interrupt the CPU when it is ready for
exchange data. The CPU execute the data
transfer and resume to its former processing.
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54. Direct Memory AccessDirect Memory Access
Draw back of programmed and interrupt
driven I/O
I/O transfer rate is limited
Processor is tied up in managing an I/O data transfer.
When dealing with a large volume of
data, more efficient method are
required-DMA
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55. Direct Memory Access(DMA)Direct Memory Access(DMA)
•Transfer large amounts of data at high speed without
continuous intervention by the processor
•Special control circuit required in the I/O device
interface, called a DMA controller
•DMA controller keeps track of memory locations,
transfers directly to memory (via the bus)
independent of the processor
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56. Direct Memory Access(DMA)Direct Memory Access(DMA)
when processor wishes to read/write, it send the
command to DMA module by issuing information
as:-
Direction of transfer,read(I/O memory) or write (memory I/O)
Address of the I/O device involved
The starting location of the block of the data in memory
The size of the block to be transferred
The processor continue with other work. It has
delegated this DMA module.
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57. Direct Memory Access(DMA)Direct Memory Access(DMA)
DMA module transfers the entire block of
data, directly from memory without involving
processor.
After completing the data transfer, DMA
modules sends interrupt signal to the
processor.
Processor only involved in beginning and end
of the transfer
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58. ADVANTAGESOF USINGADVANTAGESOF USING
DMADMA
◦ DMA can reduce the CPU waiting time of
both IO operations.
◦ DMA allows a peripheral device to read
from/write to memory without going through
the CPU
◦ DMA allows for faster processing since the
processor can be working on something else
while the peripheral can be populating
memory.
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60. Serial AND PARALLELSerial AND PARALLEL
CommunicationCommunication
Serial communication is the process of sending
data one bit at a time, sequentially, over a
communication channel or computer bus.
Parallel communication, where several bits are
sent as a whole, on a link with several parallel
channels.
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63. SynchronousSynchronous
All communication can happen at the same
time
Data is transmitted as frames of large data
blocks rather than a bulky individual bytes
More efficient method and costly compared to
asynchronous
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