Transcript CPU, Memory, and Bus systems

Hardware Components
Modified and presented by : Mohamed 1Zaki
Topics
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Simple Computer Architecture
CPU Architecture
CPU Registers
Executing instruction
Instruction set types
Memory Devices
Bus Systems
Input / Output Architecture
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COMPUTER ARCHITECTURE
Von Neumann Architecture
Address Bus
CPU/
Processor
Data Bus
Control Bus
Input & Output Devices
Main
Memory
Examples of CPUs
• Based on the manufacturer:
– Intel:
• Celeron
• Pentium I.
• Pentium MMX. ( Multimedia Extension)
• Pentium II.
• Pentium III.
• Pentium 4.
• Centrino. ( Mobile Technology)
• Core 2 DUO
• Dual core
• Quad core
• Core i series (Laptop, Desktop, and Mobile Device Processors)
• Xeon (Server and Workstation Processors)
– AMD.
– ARM
• Dual Core A4,A5, A6
• ARM Cortex-A9 MPCore (for iPad & iPhone and others)
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CPU Architecture
CPU : Central Processing Unit. Also called Processor
• CPU:
– Is the part of a computer in which arithmetic and
logical operations are performed and instructions
are decoded then executed.
• CPU Components:
• ALU ( Arithmetic and Logic Unit)
• CU (Control Unit)
• Registers:
– Are high speed & small in size temporary memory storage
areas used during data manipulation ( calculation ,
comparison , etc..)
• The clock:
• It is a circuit for generating pulses that enable
computer components to work in an ordered
manner .
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CPU Architecture
Main Memory / RAM / Primary Memory
ALU
101010
100001
Control Unit
001010
GENERAL PURPOS
REGISTER
010100
010100
CIR
100001
MAR
‫؟‬
‫؟‬
‫؟‬
Program Counter
Register
‫؟‬
MBR
‫؟‬
Bus : set of wires
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CPU Registers
• General purpose registers:
– are used to hold data before and after it is manipulated. Also used for many
operation such addition, subtraction multiplication and logic operations
• Special Purpose Registers:
– Program counter PC:
it is loaded with the address in memory of the first instruction location of a
program. After fetching, it is increased to point to the next location.
– Memory Buffer register MBR:
all data and instructions pass in and out from the main storage through MBR.
– Current instruction register CIR:
an instruction to be performed will be taken from the main storage via the
MBR and placed in register IR.
– Memory address register MAR :
prior to each transfer between the MBR and main storage , the exact source or
destination of data in the main storage must be specified by MAR.
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Executing a Software Program
The chart shows the steps that the CPU uses to execute a
software
Copy PC contents into MAR & Initiate
a memory read
Increment the PC
Copy the instruction
Which is in the MBR into CIR
Decode the CIR
Execute the instruction
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Instruction set types
Each CPU has a set of instructions

Arithmetic and Logic inst. Set:
Such as addition, subtraction, multiplication, Increment, decrement, and logical
operations, Such as add, sub,mul.

I/O instructions:
To transfer data between peripherals and memory, or between peripherals and
accumulator, Such as mov

Processor reference instructions:
To stop the microprocessor activities. Such as halt.

Fetch (Load) and store instruction:
To transfer the data between accumulator and memory, Such as load

Memory reference instructions:
To access the memory during their execution, it is both Load + store instructions.

Transfer of control, or branch instruction: (Executing a Program)
To change the program sequence. Such as jmp
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Memory Devices
• Any memory is constructed from a collection of memory
cells, each having unique address.
• Each cell contains a combination of binary data(0 or 1).
• Types of Memory:
– RAM.
– ROM.
– Cache Memory.
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Random Access Memory (RAM)
o It also called Main or Primary Memory.
o Programs & Data are stored there before processing .
o The larger amount of RAM, the quicker programs will
run.
o More than one type of RAMs are used in modern PCs,
like DRAM(Dynamic RAM) and SDRAM(Synchronous
DRAM)
o The data will be lost if the power is cut
(Volatile Memory).
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Read Only Memory (ROM)
• It holds the firmware program (BIOS).
• It starts the POST “ power on self test” program
• It contains auto-startup program that will load the
necessary OS programs in RAM.
• The information remains in the ROM when the computer
turned off. ( Nonvolatile Memory)
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The Differences between ROM
and RAM:
ROM (Read Only Memory)
RAM (Random Access Memory)
1. Used to store part of O.S. by the 1. Used to store programs such as
factory.
accounting program, games,
2. ROM can be used for read only,
word processor by the user.
we can't write or modify any thing 2. We can use the RAM for read
on the ROM.
and write data.
3. Not volatile memory (i.e. the
3. Volatile memory (i.e. the
information remains in the ROM
information in the RAM is
when the computer turned off)
removed when the power turned
off)
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Cache Memory
• Is a small memory, located close to the processor?
• Some processors are built with internal cache
memory.
• It has much shorter access time than the RAM.
Therefore, it is used to hold instructions and data
that has recently been accessed.
• There are two types of cache memory: L1 and L2.
– L1 ( Level 1) internal cache, built in with in the CPU.
– L2 ( Level 2) external cache, built in with in the
Motherboard, L2 is lager than L1. ( A+ Book p 131)
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CPU, RAM, and Cache Diagram
CPU
• Write through cache.
Cache
• Write back cache.
RAM
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Hard Disk
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Hard Disk is a data storage
device used for storing and retrieving
digital information using rapidly
rotating discs (platters) coated with
magnetic material.
A magnetic heads arranged on a
moving arm to read and write data to
the surfaces.
Disk Organization
Magnetic polarity determines
the bit value (1,0)
Sector
Bit Value is 1
Bit Value is 0
Track
0
0 1 0
1 1 1 0
The Format Command is used to create Tracks and Sectors
Other Storage Devices
Flash Memory
DVD Disks
Magnetic Tapes
Storage Device Hierarchy
Bytes
Registers
1 nsec
M Bytes
Cache
10 nsec
G Bytes
Main Memory
100 nsec
G Bytes
Flash Memory
msec
G – T Bytes
Hard Disks
msec
T Bytes
Magnetic Tapes
sec -min
Hard Disk and Tapes have mechanical movements
Others do not have and called Solid Sate Devices (SSD)
Bus Systems (Connecting them together )
• Is a collection of parallel electrical lines which
connect the computer components.
• The buses used to transfer:
– Data signals.
– Address signals.
– Control signals.
– Power.
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Bus Systems
Address Bus
– The address bus is the set of wires carrying the addressing
information used to describe the memory location, which
the data is being sent or retrieved.
– The size of the address bus indicates the maximum
amount of RAM that a chip can address.
Size of memory that can be addressed= 2L
Were L = No. of Lines in address bus
( Size of address bus)
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Bus Systems
Address Bus
Size of address
bus
Size of memory
Size of
address bus
Size of memory
1
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16
216 ~= 64 KB
2
22 =4
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220 ~= 1 MB
3
23=8
30
220=1 GB
4
24 =16
32
232=4 GB
:
:
:
:
10
210 =1024=1KB
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211=210x21=2 KB
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212=210x22=4 KB
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Bus Systems
Address Bus
Examples:
1) how many addresses can be built by 3 digits (3 lines):
2n = 23 = 8 address bus locations from
( 000 to 111 ) 2): how many addresses can be built
by 3 digits (3 lines):
2n = 23 = 8 address bus locations from ( 000 to 111 )
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Input / Output Architecture
• The computer has the ability to send and receive data to
and from other devices.
• We can transfer data in parallel and serial lines.
• When the CPU wishes to send data to a particular I/O
devices it places a unique identity code ( address ) onto the
address line.
• Only the device that recognizes that code will respond to
the command that is placed on the control line.
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