Central Processing Unit.pptx

7/29/2019 Central Processing Unit.pptx

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IntroductionAny electronic device that is capable of taking in input

data/instructions and converting them into

information/actions as outputs is called a processor.


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Building Blocks of a Processor

Transistors

Logic

Gates

Flip Flops

ProcessingUnits


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Transistor The fundamental component of

any modern processing unit.

Made by sandwiching layers ofsemi conductor substances.

Has the important properties ofbeing able to:

Work as an electronic switch. Amplify signals.


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Creators of the transistors

John Bardeen,William Shockley and

Walter Brattainat Bell Labs, 1948.

Was given the1956 Nobel Prize in Physicsfor this invention.


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Gates Processors operate on binary signals.

Binary has only two states.

On/Off Positive / Negative.

1 or 0

True or False

This rigidness had to be implemented in a electroniccircuit.


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Gates cntd. Scientists found out that by using devices like

transistors, we could implement small units which willreact like that.

These were called logic gates.

A typical gate has one or many inputs and one output.

Depending on the signal type (1 or 0 ) given to its

(input/inputs) and the internal design of it, the outputwill vary.


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Example : Half AdderAdds two 1 bit numbers

A (input 1) B (Input 2) S (Output) Carry

0 0 0 0

1 0 1 0

0 1 1 0

1 1 1 1


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Integrated circuits ,transistors and

gates

Once the transistor was

developed, its small scale sizemade the possibility of creatingmany gates on a very small pieceof semi conductor piece.

So came the era of integratedcircuits.

Typically we use silicon as the semi conductor substance


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Flip Flops Once the decision making ability was given to the

processor by use of gates, the need to store some ofthose results arose.

Various research were carried out and it was seen thatby arranging gates in special formats, it was possible tostore these values or states in an IC.

These were called flip flops (or sometimes as Latchcircuits)


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Timed flip flops Flip flops had another special property other than simply storing a

value. It could be made to work with a timing signal or a clock signal. These were known as gated f lip flops.

These will only function when a specific value of the clock signal ispresent at its clock input. When that value is not present it will not produce any output; just

retain the previous state till the desired clock signal is there.


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Round Up Transistors gave the switching ability in a compact

size.

Gates gave the decision making ability. Flip flops gave the storing and working in a time

sequence ability.

All of these together give the processor to carry out

various complex tasks in high speed.


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Central Processing Unit (CPU) It has many names but whatever the name may be the

working principals are same.

Some common names given to CPUs are: The brain of the computer

Processor or Computer Processor

Microprocessor

Central Processor

Note : Systems unit and CPU are two things. Systems unit is the whole box type

enclosure with the motherboard, processor, hard disk etc.

CPU is the processor itself.


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These names are given to the CPU because the CPUswork is just Processing or calculating. It is called asthe brain of the computer because it does all thearithmetic and logical operations.

Generally CPUs are small square chips of the size ofones palm.

The processors are made up of thin layers of thousandsof transistors (even millions). Each transistor is ofmicroscopic thickness.


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Components of a CPU: Arithmetic logical unit (ALU)

Registers

Control Unit (CU)

The ALU performs arithmetic and logical operations.The Memory Unit receives and stores the instructions

while the control unit extracts instructions from thememory and it decodes and executes them.


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Block diagram of a CPU


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ALU In computing, an arithmetic and logic unit (ALU) is

a digital circuit that performsarithmetic and logical operations.

The ALU is a fundamental building block ofthe central processing unit of a computer, and even thesimplest microprocessors contain one for purposessuch as maintaining timers.

The processors found inside modern CPUs andgraphics processing units (GPUs) accommodate verypowerful and very complex ALUs.

A single processor may contain a number of ALUs.


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History Behind the ALU Mathematician John von Neumann proposed the ALU

concept in 1945, when he wrote a report on thefoundations for a new computer called the EDVAC.Research into ALUs remains as an important partof computer science.


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ALUs Logic DiagramA,B = OperandsF = OpcodeD = StatusR = Output

Opcodeis short for Operation Codewhich is the instructions given to

the ALU.

Operands are the Data that is to beprocessed on.


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Operations of a ALUA basic ALU must be capable of carrying out the

following types of operations.

Mathematical Operations:

Addition

Subtraction

Multiplication

Division

Logical Operations

Comparisons

Complementing


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ALU working exampleMultiplication of numbers


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Same method is used in the ALU to get the answer.

There are special Gates which can store, shift and add numbers. Bycombining them the ALU gets the result.


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Control Unit (CU) The control unit coordinates the components of a

computer system. It fetches the code of all of the instructions in the program. It directs the operation of the other units by providing

timing and control signals. All computer resources are managed by the CU. It directs the flow of data between the Central Processing

Unit (CPU) and the other devices (Memory, GraphicsCards, USB, LAN etc )

The control unit was historically defined as one distinctpart of the 1946 reference model of Von Neumannarchitecture.

In a way, it is the "brain within the brain", as it controlswhat happens inside the processor, which in turn controls

the rest of the computer.


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Registers A processor register is a small amount of storage available as part

of a CPU or other digital processor.

Such registers are (typically) addressed by mechanisms otherthan main memory and can be accessed more quickly.

Almost all computers load data from a larger memory intoregisters where it is used for arithmetic, manipulated, or tested,by some machine instruction.

Manipulated data is then often stored back in main memory,either by the same instruction or a subsequent one.

A common property of computer programs is locality ofreference: the same values are often accessed repeatedly andfrequentlyused values held in registers improves performance.This is what makes fast registers (and caches) meaningful.


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Memory hierarchy in a PC


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Types of Registers in a CPUWe can find the following in a typical CPU.

Data register

Address Register

Instruction register

temporary register

Input/Output register


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Register size The main property associated with registers is its size.

Size is measured in bits.

The earlier processors had a mere 4bit registry.At present we have the 64bit capacity.

This is why the terms such as 64bit applications, 64 bitOSs, and 64bit processors came to be.


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Advantage of having larger register

sizes.A large amount of data can

be fetched and executed insingle clock cycle!!


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Advantage Cntd.A

C

E

G

B

D

F

H

A

B

C

D

E

F

G

H

Instruction decoded per cycle

32 bit 64 bit


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CPU at work1. The control unit fetches and decodes (understands)

the relevant instruction from memory registers.

2. The fetched instructions are performed by the ALU.

3. Then the results are send to the memory register for

permanent or temporary storage.

4. This goes on cyclically till the CPU is turned off.


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CPU at work


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CPU Vs Microprocessor In the days before the transistor, the CPU used to span

over many cabinets (enclosures) since the vacuumtubes used were large in size.

But once the transistor came to play, all of it was ableto be shrunk into a very small area of silicon wafer.

So all the supporting hardware of the CPU wasintegrated into a single chip and this was called the

micro processor. The main processing unit or the processor in the PC is

actually a microprocessor which contains a CPU insideof it.


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Inside a microprocessorCache : is a volatile memory areacreated inside the microprocessoritself to store frequently usedinstructions and data.

Has low capacity compared to aRAM or HDD.


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Cache Hierarchy First the CPU looks

for the relevantdata/instructionsin the L1 cache. If

found it will startexecutions. If not it will go to

the L2 and L3 soon.

If neither holds the

data it will look forit at the Ram andthen finally theHDD.

The measure of delay between data

request and delivery.


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What is Multi core?With the rapid development in silicon fabrication

technology, scientists have been able to densely packtogether many components into a single IC.

With this ability, designers began to experiment theidea of creating more CPUs in a single microprocessorchip.

So actually it is actually a collection of two or moreCPUs in a single microprocessor IC.

The term core was used instead of the term CPU toidentify them.


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A closer look Here is an enlarged

image of a quad core( 4 CPUs)

microprocessor byintel.


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Advantages of Multi-Core The CPU can only perform one Fetch Decode

instruction per clock cycle.

When you have many CPUs (cores) in onemicroprocessor, you could run many Fetch-Decodeinstructions per clock cycle.

Eg : A quad core CPU will execute 4 such instructions

in one clock cycle while a single core can do only one.


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Hertz Battle CPUs need a clock signal to perform the instructions

sequentially.

So a clock signal measured in Hertz is provided and

this was the way the efficiency/speed of the CPU wasmeasured.

But scientists found out that there is a limit to thisclock speed since increasing it caused components to :

Overheat and burn Consume high energy

So they started focusing on the multi core concept andthus the battle to increase the speed was ceased.


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Manufacturers Currently in the PC arena there are two main

manufacturers of CPUs.

Intel

AMD

Other manufactures ( handheld devices etc.)

Motorola

ARM Via technologies


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Intel Corporation is an American multinational semiconductor chipmaker corporation headquartered in Santa Clara,California.

Intel is the world's largest and highest valuedsemiconductor chip maker, based on revenue.

It is the inventor of the x86 series of microprocessors,the processors found in most personal computers.

Was founded on July 18, 1968, as Integratedelectronics.

Intel also makes motherboard chipsets, network

interface controllers and integrated circuits, flashmemory, graphic chips, embedded processors andother devices related to communications andcomputing.

Founded by semiconductor pioneers Robert Noyceand Gordon Moore.

Gordon Moore

Robert Noyce


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Moores Law Rate of increase in transistor

density on microchips

doubles every 18-24 monthswith no increase in unit cost


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AMD Corporation Advanced Micro Devices was founded onMay 1, 1969 by a group of formerexecutives from Fairchild Semiconductor,including Jerry Sanders III, Ed Turney.

The company began as a producer of logicchips, then entered the RAM chipbusiness in 1975. That same year, itintroduced a reverse-engineered clone ofthe Intel 8080 microprocessor.

It is currently the biggest competitor toIntel and recently entered the GPUproduction arena by acquiring the AtiCompany.

Jerry Sanders III

Ed Turney


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AMD Vs. Intel Intel has about 80% of the market in CPU sales.

When it comes to speed the fastest CPUs are fromIntel, yet their cost is too high.

AMD provides cost effective processors but in the Midrange to low end performance.

For a typical home user AMD processors are more

economical but for high end users Intel wins the title.


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Common terms of Microprocessors Speed = MHz, GHz

Cores = Dual, Quad, Hexa

Cache = L1, L2, L3 Socket type = Slot, PGA, LGA

FSB = Front Side Bus Speed (Not


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Socket TypeWe all know that the processor should be fixed to the

motherboard in order for the pc to function.

This connection interface is known as a socket.

It varies from model to model similar to a situationwhere you could only connect square pin plugs to asquare plug base only. So the motherboard socketmust be always matching to the processorsconnectivity area.


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The socket varies from its size, shape and the numberof pins it has.

The early processors had the slot type and Pin GridArray type sockets.The slot type has now become

obsolete and the PGA type is also becoming to thatstate gradually.

The latest processors belong to the LGA series (LandGrid Array) while the older models belong to PGA

series (Pin Grid Array). The PGA socket is a femaletype one and the LGA socket is a male type one.


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PGA Socket

LGA Socket

Slot Type Processor

Slot type motherboard socket


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Front Side Bus (FSB) This is the main data

path between theprocessor and the rest ofthe system.

So higher the bus speed,higher the efficiency ofthe processor.

This is no longer used in

the newer Core I seriessince they have ceasedusing of the North bridgeChip architecture.


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MicrocontrollersA microcontroller is actually a computer.

The desktop computer you are using is a "generalpurpose computer" that can run any of thousands ofdifferent programs.

Microcontrollers are "special purpose computers."Microcontrollers do one thing well.

There are a number of other common characteristicsthat define microcontrollers. If a computer matches amajority of these characteristics, then you can call it a"microcontroller":


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Features of a Microcontroller They are "embedded" inside some other device (often aconsumer product) so that they can control the features oractions of the product. Another name for a microcontroller,therefore, is "embedded controller. Eg : The controllersinside the mouse, keyboard, monitors, scanners etc.

Microcontrollers are dedicated to one taskand run onespecific program. The program is stored in ROM(read-onlymemory) and generally does not change.

Microcontrollers are often low-power devices. A desktopcomputer is almost always plugged into a wall socket andconsume atleast 50 watts of electricity. A battery-operatedmicrocontroller might consume 50 milliwatts.


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Features cntd. A microcontroller is often small and low cost. The componentsare chosen to minimize size and to be as inexpensive as possible.

A microcontroller is often, but not always, ruggedizedin someway. The microcontroller controlling a car's engine, for example, has to

work in temperature extremes that a normal computer generallycannot handle. A car's microcontroller in Alaska has to work fine in-30 degree F (-34 C) weather, while the same microcontroller inNevada might be operating at 120 degrees F (49 C). When you add

the heat naturally generated by the engine, the temperature can goas high as 150 or 180 degrees F (65-80 C) in the enginecompartment.

On the other hand, a microcontroller embedded inside a VCRhasn't been ruggedized at all.


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Manufacturers

Some of the leading chip manufacturers

Microchip technology

Atmel

Xilinx

Texas Instruments

Fujitsu


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Why do we need microcontrollers?


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The End.

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Central Processing Unit.pptx