btec national - computer systems 1 computer systems week 1 the basics – system unit components

Btec National - COMPUTER SystemsBtec National - COMPUTER Systems 11

Computer Systems Week 1Computer Systems Week 1

The Basics – System Unit The Basics – System Unit ComponentsComponents


AimsAims

Discussion into what will be covered in this Discussion into what will be covered in this UnitUnit

Understand the basic principlesUnderstand the basic principles

Gain an understanding into the system Gain an understanding into the system componentscomponents

A knowledge of BusesA knowledge of Buses


What is covered in this Unit?What is covered in this Unit?

Computer systemsComputer systems– System Unit componentsSystem Unit components– PeripheralsPeripherals– Computer selection (complete systems)Computer selection (complete systems)

Operating systemsOperating systems– Operating system functionsOperating system functions– Computer operations (i.e. files structures, Computer operations (i.e. files structures,

tailoring of interface (user need))tailoring of interface (user need))


What is covered in this Unit? – What is covered in this Unit? – Cont.Cont.

Design a computer system Design a computer system – Selection (i.e. processor, memory, storage)Selection (i.e. processor, memory, storage)– User needs (Costs, particular requirements)User needs (Costs, particular requirements)


Basic principlesBasic principles

– – Computer configurationComputer configuration

CPUCentral Processing UnitInput device Output device

• keyboard• mouse• microphone

• screen• printer• speaker

Can you name any other input and output devices?Can you name any other input and output devices?


Basic principles – Cont.Basic principles – Cont.

Input devicesInput devices

CPUCentral Processing Unit

Input device Output device

Input devicesInput devices

Capture information from the real worldCapture information from the real world

Send data to the CPUSend data to the CPU



Output devicesOutput devices

CPUCentral Processing UnitInput device Output device

Output devicesOutput devices

Are sent data by the CPUAre sent data by the CPU

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



What is dataWhat is data– Data is unorganised facts, numbers, Data is unorganised facts, numbers,

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

What is information?What is information?– Information is data which has been Information is data which has been

assigned a commonly understood assigned a commonly understood meaning.meaning.(Human understanding)(Human understanding)



Where is data storedWhere is data stored

CPUCentral Processing Unit

Input device Output device

Main memory

Backing store

• Hard disk• USB device

• CD• DVD

• RAM



How is data storedHow is data stored– All computer data is stored as binary patterns.All computer data is stored as binary patterns.– Binary patterns are combinations of 1s and Binary patterns are combinations of 1s and

0s, e.g. 100010010011100s, e.g. 10001001001110– Each 1 or 0 is known as a bit.Each 1 or 0 is known as a bit.– Binary patterns are usually stored in groups of Binary patterns are usually stored in groups of

8, 16, 24, 32 or 64 bits.8, 16, 24, 32 or 64 bits.


System ComponentsSystem Components

Have a go at the online test – Before we Have a go at the online test – Before we move on (Quiz-Hardware-Parts)move on (Quiz-Hardware-Parts)


System Components – Cont.System Components – Cont.

The main system unit components are:The main system unit components are:– CPU (Central processing unit)CPU (Central processing unit)– Cache MemoryCache Memory– Internal Memory: RAM – Random Access Internal Memory: RAM – Random Access

Memory, ROM – Read Only MemoryMemory, ROM – Read Only Memory– Hard diskHard disk– MotherboardMotherboard



CPU (Central Processing Unit)CPU (Central Processing Unit)– 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 Controls the transmission of information from main memory to output devicesmain memory to output devices



CPU – How it worksCPU – How it works

A CPU - also known as a microprocessor - is a complete computation engine that is fabricated

on a single chip.



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.



CPU – CPU – fetch-decode execute cyclefetch-decode execute cycle– The fundamental operation of most CPUs, The fundamental operation of most CPUs,

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



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

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

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



CPU – CPU – fetch-decode execute cyclefetch-decode execute cycle– 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 Often, one group of numbers in the instruction, called the opcode, indicates which operation to perform. The remaining opcode, indicates which operation to perform. The remaining parts of the number usually provide information required for that parts of the number usually provide information required for that instruction, such as operands for an addition operation. instruction, such as operands for an addition operation.



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

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



CPU – CPU – Clock SpeedClock Speed– To synchronize the steps of the fetch-decode To synchronize the steps of the fetch-decode

execute cycle, all processors have an internal execute cycle, all processors have an internal clock which generates regularly timed pulses. clock which generates regularly timed pulses.

– All activities of the fetch-decode-execute cycle All activities of the fetch-decode-execute cycle must begin on a clock pulsemust begin on a clock pulse.(.(megahertz megahertz (MHz) or gigahertz (GHz).)(MHz) or gigahertz (GHz).)



CPU – CPU – Word SizeWord Size– A word is simply a fixed-sized group of bits A word is simply a fixed-sized group of bits

that are handled together by the CPU.that are handled together by the CPU.– The word size is the number of bits that the The word size is the number of bits that the

CPU can process simultaneously.CPU can process simultaneously.– Normally groups of 8, 16, 32, 64, 128 bit Normally groups of 8, 16, 32, 64, 128 bit

words are processed as a unit during input, words are processed as a unit during input, output and logic instructions.output and logic instructions.


System Components – Cont.System Components – Cont.CPU – Cache MemoryCPU – Cache Memory

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

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

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

– L2 cache can be on the motherboard, located between the CPU and RAML2 cache can be on the motherboard, located between the CPU and RAM– L1 cache is part of the CPU itself. L1 cache is part of the CPU itself.

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



Internal MemoryInternal Memory– RAM (Random Access Memory)RAM (Random Access Memory)– ROM (Read Only Memory)ROM (Read Only Memory)



RAMRAM– RAM can be altered; it is the main memory RAM can be altered; it is the main memory

used in the system to store data and used in the system to store data and programs whilst the computer is running.programs whilst the computer is running.

Its contents are lost when power is removed Its contents are lost when power is removed (volatile storage).(volatile storage).



RAM - exists in many different formatsRAM - exists in many different formats– SRAMSRAM – – SStatic tatic RRandom andom AAccess ccess MMemoryemory

More expensive memory, normally reserved for cache memory; fast More expensive memory, normally reserved for cache memory; fast because its data doesn’t need to be refreshed electronically.because its data doesn’t need to be refreshed electronically.

– DRAMDRAM – – DDynamic ynamic RRandom andom AAccess ccess MMemoryemoryCheaper and slower than SRAM because its data needs to be Cheaper and slower than SRAM because its data needs to be periodically refreshed.periodically refreshed.

– SDRAMSDRAM – – SSynchronous ynchronous DDynamic ynamic RRandom andom AAccess ccess MMemoryemoryAll the features of DRAM but faster as it can access multiple data All the features of DRAM but faster as it can access multiple data addresses at the same time. Its primary advantage is that its speed addresses at the same time. Its primary advantage is that its speed is synchronised to the speed of the processor.is synchronised to the speed of the processor.



ROMROM– Read-only memoryRead-only memory is a class of storage is a class of storage

media used in computers and other electronic media used in computers and other electronic devices. Because data stored in ROM it devices. Because data stored in ROM it cannot be modified (at least not very quickly cannot be modified (at least not very quickly or easily), it is mainly used to by firmware or easily), it is mainly used to by firmware (i.e. (i.e. BIOS – Basic Input Output System used to identify and initialize BIOS – Basic Input Output System used to identify and initialize system component hardware such as the video display card, system component hardware such as the video display card, hard disk etc)hard disk etc)



Hard disk - Commonly either:Hard disk - Commonly either:– PATAPATA (IDE - (IDE - Integrated Drive ElectronicsIntegrated Drive Electronics interface) interface)

– older parallel technology which has 2 channels, – older parallel technology which has 2 channels, each supporting a slave and master deviceeach supporting a slave and master device

– SATASATA (IDE - (IDE - Integrated Drive ElectronicsIntegrated Drive Electronics interface) interface) – newer serial technology (hot swapping)– newer serial technology (hot swapping)

– Hard drives provide permanent storage of data and Hard drives provide permanent storage of data and programs which would otherwise be lost from a programs which would otherwise be lost from a computer’s RAM when power is removed (non-volatile computer’s RAM when power is removed (non-volatile storage).storage).



MotherboardMotherboard– 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))



MotherboardMotherboardmedia.arstechnica.com


BusesBuses

BusesBuses– A bus is a collection of A bus is a collection of parallel data tracksparallel data tracks

on the motherboard used to permit data flow on the motherboard used to permit data flow betweenbetween subsystems. subsystems.

– Common examples include the Common examples include the data data bus, bus, addressaddress bus, bus, controlcontrol bus and the bus and the processorprocessor bus.bus.


BusesBuses

Data busData bus– The data bus is used to transmit the actual The data bus is used to transmit the actual

data to the different components on the data to the different components on the motherboardmotherboard

– The width of a data bus determines how many The width of a data bus determines how many bits can be transmitted simultaneously and bits can be transmitted simultaneously and the maximum address which can be the maximum address which can be referenced.referenced.


BusesBuses

Address busAddress bus– An An address busaddress bus is a computer bus, controlled is a computer bus, controlled

by the CPU for specifying the physical by the CPU for specifying the physical addresses of computer memory elements that addresses of computer memory elements that the requesting unit wants to access (read or the requesting unit wants to access (read or write).write).


BusesBuses

Control busControl bus– A A control buscontrol bus is (part of) a computer bus, used by is (part of) a computer bus, used by

CPU for communicating with other devices within the CPU for communicating with other devices within the computer. While the address bus carries the computer. While the address bus carries the information on which device the CPU is information on which device the CPU is communicating with and the data bus carries the communicating with and the data bus carries the actual data being processed, the control bus carries actual data being processed, the control bus carries commands from the CPU and returns status signals commands from the CPU and returns status signals from the devices, for example if the data is being read from the devices, for example if the data is being read or written to the device the appropriate line (read or or written to the device the appropriate line (read or write) will be active. write) will be active.


BusesBuses

Processor busProcessor bus– This is also called the This is also called the ffront ront siside de bbus (us (FSBFSB).).

It is the It is the bidirectional link bidirectional link between the between the

motherboard motherboard and the and the processor processor itself.itself.– The The Front Side BusFront Side Bus ( (FSBFSB) is the data) is the data

transfer bus that carries information betweentransfer bus that carries information between

the CPU and the Northbridge of thethe CPU and the Northbridge of the

Motherboard.Motherboard.


ConclusionConclusion

We discussed the Unit outcomesWe discussed the Unit outcomes

Looked into the basic principles of a Looked into the basic principles of a computer systemcomputer system

Discussed the system unit componentsDiscussed the system unit components

Acquired a knowledge of system busesAcquired a knowledge of system buses

btec national - computer systems 1 computer systems week 1 the basics – system unit components

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