Computer Components Week 1

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Computer ComponentsWeek 1

• System Unit Components

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Aims

• Discussion into what will be covered in this Unit
• Understand the basic principles
• Gain an understanding into the system components
• A knowledge of Buses

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Basic principles

• Computer configuration

• keyboard
• mouse
• microphone

• screen
• printer
• speaker

Can you name any other input and output devices?
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Basic principles Cont.

• Input devices

• Input devices
• Capture information from the real world
• Send data to the CPU

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Basic principles Cont.

• Output devices

• 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 Cont.

• What is data
• Data 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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Basic principles Cont.

• Where is data stored

• Hard disk
• USB device

• CD
• DVD

• RAM

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Basic principles Cont.

• How is data stored
• All computer data is stored as binary patterns.
• Binary patterns are combinations of 1s and 0s,
  e.g. 10001001001110
• Each 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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System Components

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

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System Components Cont.

• The main system unit components are
• CPU (Central processing unit)
• Cache Memory
• Internal Memory RAM Random Access Memory, ROM
  Read Only Memory
• Hard disk
• Motherboard

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System Components Cont.

• CPU (Central Processing Unit)
• Controls the transmission of data from input
  devices to memory
• Processes the data held in main memory
• Controls the transmission of information from
  main memory to output devices

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System Components Cont.

• CPU 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.

• 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.

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

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System Components Cont.

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

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System Components Cont.

• CPU fetch-decode execute cycle
• Decode
• The instruction that the CPU fetches from memory
  is used to determine what the CPU is to do. In
  the decode step, the instruction is broken up
  into parts that have significance to other
  portions of the CPU.
• The way in which the numerical instruction value
  is interpreted is defined by the CPU's
  instruction set architecture (ISA).
• Using the Internet research and take notes into
  instruction set architecture.
• Often, one group of numbers in the instruction,
  called the opcode, indicates which operation to
  perform. The remaining parts of the number
  usually provide information required for that
  instruction, such as operands for an addition
  operation.

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System Components Cont.

• CPU fetch-decode execute cycle
• Execute
• During this step, various portions of the CPU
  are connected so they can perform the desired
  operation.
• If, for instance, an addition operation was
  requested, an arithmetic logic unit (ALU) will be
  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 final sum.

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System Components Cont.

• CPU Clock Speed
• To synchronize the steps of the fetch-decode
  execute cycle, all processors have an internal
  clock which generates regularly timed pulses.
• All activities of the fetch-decode-execute cycle
  must begin on a clock pulse.(megahertz (MHz) or
  gigahertz (GHz).)

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System Components Cont.

• CPU Word Size
• A word is simply a fixed-sized group of bits that
  are handled together by the CPU.
• The word size is the number of bits that the CPU
  can process simultaneously.
• Normally groups of 8, 16, 32, 64, 128 bit words
  are processed as a unit during input, output and
  logic instructions.

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System Components Cont.

• 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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System Components Cont.

• Internal Memory
• RAM (Random Access Memory)
• ROM (Read Only Memory)

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System Components Cont.

• RAM
• RAM can be altered it is the main memory used in
  the system to store data and programs whilst the
  computer is running.
• Its contents are lost when power is removed
  (volatile storage).

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System Components Cont.

• RAM - exists in many different formats
• SRAM Static Random Access Memory
• More expensive memory, normally reserved for
  cache memory fast because its data doesnt need
  to be refreshed electronically.
• DRAM Dynamic Random Access Memory
• Cheaper and slower than SRAM because its data
  needs to be periodically refreshed.
• SDRAM Synchronous Dynamic Random Access Memory
• 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 is
  synchronised to the speed of the processor.

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System Components Cont.

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

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System Components Cont.

• Hard disk - Commonly either
• PATA (IDE - Integrated Drive Electronics
  interface) older parallel technology which has
  2 channels, each supporting a slave and master
  device
• SATA (IDE - Integrated Drive Electronics
  interface) newer serial technology (hot
  swapping)
• Hard drives provide permanent storage of data and
  programs which would otherwise be lost from a
  computers RAM when power is removed
  (non-volatile storage).

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System Components Cont.

• 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)

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System Components Cont.

• Motherboard

media.arstechnica.com
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Buses

• Buses
• A bus is a collection of parallel data tracks on
  the motherboard used to permit data flow between
  subsystems.
• Common examples include the data bus, address
  bus, control bus and the processor bus.
• Using the Internet research into the various
  types of buses.

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Buses

• Data bus
• The data bus is used to transmit the actual data
  to the different components on the motherboard
• The width of a data bus determines how many bits
  can be transmitted simultaneously and the maximum
  address which can be referenced.

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Buses

• Address bus
• An address bus is a computer bus, controlled by
  the CPU for specifying the physical addresses of
  computer memory elements that the requesting unit
  wants to access (read or write).

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Buses

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

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Buses

• Processor bus
• This is also called the front side bus (FSB).
• It is the bidirectional link between the
• motherboard and the processor itself.
• The Front Side Bus (FSB) is the data
• transfer bus that carries information between
• the CPU and the Northbridge of the
• Motherboard.

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Conclusion

• We discussed the Unit outcomes
• Looked into the basic principles of a computer
  system
• Discussed the system unit components
• Acquired a knowledge of system buses