computer architecture full chapter by fazal rehman (shamil) itc : by fazal rehman(shamil)1

• Computer ArchitectureFull Chapter

• By Fazal Rehman (Shamil)

ITC : By Fazal Rehman(Shamil) 1

Objectives Overview


The System Unit

• The system unit is a case that contains electronic components of the computer used to process data


The System Unit

• The inside of the system unit on a desktop personal computer includes:


The System Unit

• The motherboard is the main circuit board of the system unit– A computer chip contains integrated circuits


Processor

• The processor, also called the central processing unit (CPU), interprets and carries out the basic instructions that operate a computer– Contain a control unit and an arithmetic logic unit (ALU)


multi-core processor

• A multi-core processor is a single computing component with two or more independent actual CPU’s.

ITC : By Fazal Rehman(Shamil)8

Model Core i3 Core i5 Core i7

Number of cores

2 4 4

• Quad Cores has 4 cores• Core 2 due has 2 cores• Dual core has 2 cores


Processor


Processor

• The control unit is the component of the processor that directs and coordinates most of the operations in the computer

• The arithmetic logic unit (ALU) performs arithmetic, comparison, and other operations


Processor

• For every instruction, a processor repeats a set of four basic operations, which comprise a machine cycle


Processor


Data Representation


Data Representation

A computer circuit represents the 0 or the 1 electronically by the presence or absence of an electrical charge

Eight bits grouped together as a unit are called a byte. A byte represents a single character in the computer


Data Representation

• ASCII (American Standard Code for Information Interchange) is the most widely used coding scheme to represent data


Data Representation


Cache

• The speed of CPU is extremely high compared to the access time of main memory.

• Therefore the performance of CPU decreases due to the slow speed of main memory.

SO• CPU required its own memory.• The solution to this problem are Cache memory and

registers.


Cache

• Cache Memory is a small memory chip is attached between CPU and Main memory whose access time is very close to the processing speed of CPU.

• CACHE memories are accessed much faster than conventional RAM. It is used to store programs or data currently being executed or temporary data


Register

• Register is a small amount of memory available as part of a digital processor, such as a CPU. Such registers are (typically) addressed by mechanisms other than main memory and can be accessed faster.

• Processor registers are normally at the top of the memory hierarchy, and provide the fastest way to access data.


Examples of registers

• PCR-Program counter Register:• Controls the sequence in which instructions are fetched

from memory.• It stores the address of next instruction to be fetched

for execution.



• MAR-Memory Address Register:Holds the memory addresses of data and instructions.



IR- Instruction Register:

• Once an instruction is fetched from main memory, it is stored in the instruction register.



• MBR- Memory Buffer Register:• Holds the contents of data or instructions read from, or

written in memory.• Also called data register.



• Accumulator Register:• Located inside ALU. • Used during arithmetic and logical operations


Memory

• Memory consists of electronic components that store instructions waiting to be executed by the processor, data needed by those instructions, and the results of processing the data

• Stores three basic categories of items:


Memory

• Each location in memory has an address• Memory size is measured in kilobytes (KB or K), megabytes

(MB), gigabytes (GB), or terabytes (TB)


Memory

• The system unit contains two types of memory:


Memory


Memory

• Three basic types of RAM chips exist:


• SRAM• It is faster than DRAM.• It is more expensive as compared to DRAM.• It does not need to be power – refreshed.• It utilizes less power.• It holds data indefinitely as long as the computer is

turned on.• It is more complex and less compact.


• DRAM• It is slower than SRAM.• It is less expensive.• It has to be refreshed after each read operation.• It utilizes more power.• It holds data dynamically not indefinitely.• It is less complex and more compact.


• MRAM (Magneto resistive Random Access Memory)• MRAM stands for Magneto resistive Random Access Memory. It

stores data using magnetic charges instead of electrical charges. MRAM uses far less power than other RAM technologies so it is ideal for portable devices. It also has greater storage capacity. It has faster access time than RAM. It retains its contents when the power is removed from computer.


Memory

• RAM chips usually reside on a memory module and are inserted into memory slots


Memory

• The amount of RAM necessary in a computer often depends on the types of software you plan to use

• Memory cache speeds the processes of the computer because it stores frequently used instructions and data


Memory


Read Only Memory (ROM) Types

• Basic ROM types:• ROM - Read Only Memory• PROM - Programmable Read Only Memory• EPROM - Erasable Programmable Read Only Memory.

– Data can be erased by special devices.

• EEPROM - Electrically Erasable Programmable Read Only Memory– Data can be erased by electrical pulses


Memory

• Flash memory can be erased electronically and rewritten– CMOS technology provides

high speeds and consumes little power


Memory

• Access time is the amount of time it takes the processor to read from memory– Measured in nanoseconds


Expansion Slots and Adapter Cards

• An expansion slot is a socket on the motherboard that can hold an adapter card

• An adapter card enhances functions of a component of the system unit and/or provides connections to peripherals– Sound card and video card


Expansion Slots and Adapter Cards

• Removable flash memory includes:– Memory cards, USB flash drives, and PC Cards/ExpressCard

modules


Ports and Connectors



• On a notebook computer, the ports are on the back, front, and/or sides



• A USB port can connect up to 127 different peripherals together with a single connector– You can attach multiple peripherals using a single USB port with a

USB hub



• A port replicator is an external device that provides connections to peripherals through ports built into the device

• A docking station is an external device that attaches to a mobile computer or device


Buses• A bus allows the various devices

both inside and attached to the system unit to communicate with each other– Data bus– Address bus

• A computer can have these basic types of buses:– System bus– Backside bus– Expansion bus


Bays

• A bay is an opening inside the system unit in which you can install additional equipment– A drive bay typically holds disk

drives


Power Supply


Putting It All Together


Summary


computer architecture full chapter by fazal rehman (shamil) itc : by fazal rehman(shamil)1

Documents

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