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Unit 2: Computer Systems

Session One Part One

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Aims:

Discussion into what will be covered in this unit.AssessmentUnderstand the basic principlesGain an understanding into the system components

Power supplyMotherboardChipsetsProcessorCache Memory

(Continued on Part 2)

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What is covered?

Computer componentsInternal system unit componentsPeripheralsBacking storageOperating system softwareSoftware utilities

Recommend computer systemsOrganisational requirements

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What is covered?

Set up and maintain computer systemsInstall hardware and softwarePC ConfigurationTestingMaintenance

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How will you be assessed?

Two AssignmentsPractical observations within a system support lab

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Basic Principles

CPUCentral Processing UnitInput device Output device

• keyboard• mouse• microphone

• screen• printer• speaker

Can you name any other input and output devices?

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Input devices

CPUCentral Processing Unit

Input device Output device

Input devicesCapture information from the real worldSend data to the CPU

Basic Principles

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Basic Principles

Output devices

CPUCentral Processing UnitInput device Output device

Output devices

Are sent data by the CPU

Convert the data to an understandable form, e.g. images on screen, sounds, printed text

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Basic Principles

Where is data stored

CPUCentral Processing Unit

Input device Output device

Main memory

Backing store

• Hard disk• USB device

• CD• DVD

• RAM

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Basic Principles

How is data storedAll computer data is stored as binary patterns.Binary patterns are combinations of 1s and 0s,

e.g. 10001001001110Each 1 or 0 is known as a bit.Binary patterns are usually stored in groups of

8, 16, 24, 32 or 64 bits.

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Basic Principles

What is dataData is unorganised facts, numbers, letters and

symbols represented in a formalised manner suitable for communication, interpretation and processing by computers. (Binary code)

What is information?Information is data which has been assigned a

commonly understood meaning. (Human understanding)

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System components

Power

Motherboard

Chipsets

The Processor

System Memory

Video Cards

System Case

Monitors

Hard Disk Drives

CD-ROM Drives

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PowerThe power supply converts the alternating current (AC) line from your home to the direct current (DC) needed by the personal computer.

Power supplies, often referred to as "switching power supplies", use switcher technology to convert the AC input to lower DC voltages. The typical voltages supplied are:

3.3 volts 5 volts 12 volts

The 3.3- and 5-volts are typically used by digital circuits, while the 12-volt is used to run motors in disk drives and fans. The main specification of a power supply is in watts. A watt is the product of the voltage in volts and the current in amps

http://computer.howstuffworks.com/power-supply.htm

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Motherboard

This is the main circuit board that all of the other internal components connect to.

The CPU and memory are usually on the motherboard. Other systems may be found directly on the motherboard or connected to it through a secondary connection.

For example, a sound card can be built into the motherboard or connected through PCI (Peripheral Component Interface) or a graphics card connected via the AGP (Accelerated Graphics Port)

http://www.tech-faq.com/motherboard.html

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Motherboard ContinuedThe most important thing to remember about the motherboard is that it is a printed circuit board which provides all the connections, pathways and "lines" connecting the different components of the computer to each other - specifically, the Central Processing Unit or CPU, which is where (as its name implies) all the "processing" is going on to everything else.

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ChipsetsA set of chips that provides the interfaces between all of the PC's subsystems. It provides the buses and electronics to allow the CPU, memory and input/output devices to interact.

The most important connections are to the chipsets - especially the Northbridge chipset which is connected to the main computer memory (RAM, AGP), while the Southbridge set is connected to the peripherals -IDE controllers, BIOS etc.

http://en.wikipedia.org/wiki/Chipset

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Processor

A CPU - also known as a microprocessor - is a complete computation engine that is fabricated on a single chip. Often referred to as the brain

of the computer.

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Processor Continued

Controls the transmission of data from input Controls the transmission of data from input devices to memorydevices to memory

Processes the data held in main memoryProcesses the data held in main memory

Controls the transmission of information from main Controls the transmission of information from main memory to output devicesmemory to output devices

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Processor Continued

The CPU uses its ALU (Arithmetic Logic Unit) to enable it to perform mathematical operations like addition, subtraction, multiplication and division.

Modern CPUs contain complete floating point processors that can perform extremely sophisticated operations on large floating point numbers.

A CPU can move data from one memory location to another.

A CPU can make decisions and jump to a new set of instructions based on those decisions.

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Processor Continued

CPU – CPU – fetch-decode execute cyclefetch-decode execute cycle

The fundamental operation of most CPUs, regardless of the physical The fundamental operation of most CPUs, regardless of the physical form they take, is to execute a sequence of stored instructions called a form they take, is to execute a sequence of stored instructions called a program. This is achieved by using the fetch-decode and execute program. This is achieved by using the fetch-decode and execute cycle.cycle.

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FetchFetch

Fetch involves retrieving an instruction from program memory.Fetch involves retrieving an instruction from program memory.

The location in program memory is determined by a program The location in program memory is determined by a program counter (PC), the program counter keeps track of the CPU's place counter (PC), the program counter keeps track of the CPU's place in the current program. Often the instruction to be fetched must be in the current program. Often the instruction to be fetched must be retrieved from relatively slow memory, causing the CPU to stall retrieved from relatively slow memory, causing the CPU to stall while waiting for the instruction to be returned. This issue is largely while waiting for the instruction to be returned. This issue is largely addressed in modern processors by caches.addressed in modern processors by caches.

Processor Continued

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DecodeDecode

The instruction that the CPU fetches from memory is used to The instruction that the CPU fetches from memory is used to determine what the CPU is to do. In the determine what the CPU is to do. In the decodedecode step, the step, the instruction is broken up into parts that have significance to other instruction is broken up into parts that have significance to other portions of the CPU.portions of the CPU.

The way in which the numerical instruction value is interpreted is The way in which the numerical instruction value is interpreted is defined by the CPU's instruction set architecture (defined by the CPU's instruction set architecture (ISAISA).).Often, one group of numbers in the instruction, called the opcode, Often, one group of numbers in the instruction, called the opcode, indicates which operation to perform. The remaining parts of the indicates which operation to perform. The remaining parts of the number usually provide information required for that instruction, number usually provide information required for that instruction, such as operands for an addition operation.such as operands for an addition operation.

Processor Continued

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ExecuteExecute

During this step, various portions of the CPU are connected so During this step, various portions of the CPU are connected so they can perform the desired operation. If, for instance, an addition they can perform the desired operation. If, for instance, an addition operation was requested, an arithmetic logic unit (operation was requested, an arithmetic logic unit (ALUALU) will be ) will be connected to a set of inputs and a set of outputs. The inputs connected to a set of inputs and a set of outputs. The inputs provide the numbers to be added, and the outputs will contain the provide the numbers to be added, and the outputs will contain the final sum.final sum.

Processor Continued

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Types of CPU

Intel and Advanced Micro Devices (AMD) lead the market in terms of speed and quality.

Intel's desktop CPUs include Celeron, Pentium, and Core.

AMD's desktop processors include Sempron, Athlon, and Phenom.

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Cache Memory CPU – Cache Memory

high-speed memory used as a temporary store for recently processed instructions and data, or those which the CPU predicts will be processed soon

Much quicker to access instructions and data from cache memory than requesting it from normal RAM

Two types of cache exist, Level 2 (L2) and Level 1 (L1)

L2 cache can be on the motherboard, located between the CPU and RAM

L1 cache is part of the CPU itself.

Cache memory is typically very expensive, so would be prohibitive in great quantities.

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Types of CPU continued

Getting a processor with a dual, triple, or quad core can make a significant difference in the processing power of your computer.

It's like having two, three, or four separate processors installed on your computer at one time.

These processors work together to make your computer multitask faster and with greater efficiency. Getting a CPU with a larger front side bus can enhance the processor's ability to communicate with RAM, which will increase your computer's overall speed.

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Conclusion:

Discussed what will be covered in this unitOutlined the Assessment strategyDemonstrated some Understanding into the basic principlesGained an understanding into the system components

Power supplyMotherboardChipsetsProcessorCache Memory

(Continued on Part 2)