Btec National - COMPUTER Sy Btec National - COMPUTER Sy stems stems 1 Computer Systems Week Computer Systems Week 1 1 The Basics – System The Basics – System Unit Components Unit Components
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Computer Systems Week 1Computer Systems Week 1
The Basics – System Unit The Basics – System Unit ComponentsComponents
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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
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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))
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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)
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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?
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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
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Basic principles – Cont.Basic principles – Cont.
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
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Basic principles – Cont.Basic principles – Cont.
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)
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Basic principles – Cont.Basic principles – Cont.
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
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Basic principles – Cont.Basic principles – Cont.
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.
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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)
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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
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System Components – Cont.System Components – Cont.
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
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System Components – Cont.System Components – Cont.
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.
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System Components – Cont.System Components – Cont.
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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System Components – Cont.System Components – Cont.
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.
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System Components – Cont.System Components – Cont.
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.
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System Components – Cont.System Components – Cont.
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.
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System Components – Cont.System Components – Cont.
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.
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System Components – Cont.System Components – Cont.
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).)
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System Components – Cont.System Components – Cont.
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.
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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.
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System Components – Cont.System Components – Cont.
Internal MemoryInternal Memory– RAM (Random Access Memory)RAM (Random Access Memory)– ROM (Read Only Memory)ROM (Read Only Memory)
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System Components – Cont.System Components – Cont.
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).
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System Components – Cont.System Components – Cont.
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.
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System Components – Cont.System Components – Cont.
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)
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System Components – Cont.System Components – Cont.
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).
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System Components – Cont.System Components – Cont.
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))
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System Components – Cont.System Components – Cont.
MotherboardMotherboardmedia.arstechnica.com
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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.
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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.
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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).
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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.
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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.
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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