3.1 Hardware

Cards (21)

  • Central Processing Unit (CPU) contains?
    - control unit ( CU )
    - arithmetic logic unit (ALU)
    - registers and buses

    Also
    -system clock
    Primary memory
  • A microprocessor is a
    - is an integrated circuit (microchip) designed to process instructions
    - It is the most important, and usually the most expensive, component of a digital device
  • Von Neumann Architecture introduced?
    - concept of CPU
    - processor able to access memory directly
    - computer memories could store programs as well as data
    - stored programs made up of instructions which could be executes in sequential order
  • Components of the CPU :

    ALU
    - Performs arithmetic and logical operations on data (e.g ADD, MULTIPLY)...
    - Boolean logic operations such as AND, OR...
    - allows multiplication + division using shifting operators

    - computers can have more than one ALU
  • Components of the CPU :

    Control Unit
    - reads instructions from memory

    - signals are generated during Fetch-Decode-Execute cycle to control all components of the computer

    - control unit synchronises data flow and program instructions throughout the computer
  • Components of the CPU :

    Registers
    - registers can be general purpose or special purpose

    - high speed areas of memory within a CPU - used to store small amounts of data, address of next instruction to be executed or current instruction being decoded.

    - registers include : current instruction registers (CIR), accumulator (ACC), memory address register (MAR), memory data/buffer register (MDR), program counter (PC)

    - are used in FDE cycle
  • System clock
    - used to produce timing signals on the control bus to ensure all functions are synchronised

    - changing clock speed can improve performance but there is always the risk of overclocking —> can lead to system crashes
  • Components of the CPU :

    System buses
    3 types of buses
    - transfer data and control throughout computer

    - use parallel data transfer and width of bus can ber according to bus architecture

    Address bus - unidirectional - carries addresses throughout the system
    Data bus - bidirectional - allows data to be carried to/from CPU/memory and to/from input-output
    Control bus - bidirectional - carries signals from the CU to all computer components

    Width of bus determines the word length/size and the performance of the computer
  • Components of the CPU :

    RAM

    -Random access M (RAM) holds data, programs and part of the operating system currently in use

    - often known as Immediate Access store (IAS)

    - all data being used in programs needs to be transferred to the RAM

    - Memory is made up of an address and its content; address identifies the location of data and instructions

    - all memory location are unique

    - primary memory also includes read-only memory (ROM) which cannot be altered, contains the start- up routines for the computer
  • Fetch part of FDE cycle (4)
    1) PC contains address of memory location of next instruction to be fetched from me memory (MAR)

    2) address is copied from PC to the MAR using the address bus

    3) contents of memory location contained in MAR copied into MDR

    4) contentes of MDR then copied to CIR and the PC is incremented by one so next instruction can be processed
  • Decode part of FDE cycle
    1) instruction now decoded so that it can be interpreted by next part of cycle
  • Execute part of FDE cycle
    1) CPU passes decoded instructions as a set of control signals to appropriate computer components

    2) this allows each instruction to be carried out in a logical sequence
  • Cache?
    Store frequently used instruction and data, can speed up CPU performanance
    - larger cache better CPU performance
  • Cores
    Once core made up of an ALU, A CU and registers.

    A quad core has four independently operating units that can read and execute CPU instruction
  • Overclocking
    Caused by changing clock speed in Basic Input/ Output System
    - can lead to over heating and non-synchronised instruction s
    - which can cause computer to crash
  • Embedded system?
    A computer system with a dedicated function within a larger electrical or mechanical system.
  • Parts of embedded system
    Microcontroller : made up of a CPU with RAM, ROM and peripherals all embedded on a single chip to carry out a specific task

    Microprocessor : Integrated circuit consisting of CPU ONLY

    System on a chip : may contain a microcontroller as one of components : usually includes CPU, memory, input/output lifts and secondary storage
    All on a single chip
  • General makeup of an embedded system
    Analogue or digital input, embedded systems can contain sensor input, mechanical components, actuators and software, modern systems use dual and quad core CPUs and variety of I/O connections
  • eg embedded systems
    - washing machines
    - vending machines
  • Benefits of embedded systems
    1. can perform a small number of specific tasks.

    2.Cheap to produce

    3.Use very little power(energy efficient)

    4. components are small compared to other computer systems
  • Drawbacks of embedded systems
    1) can be difficult to upgrade some devices to take advantage of new technology

    2)troubleshooting faults in the device is a specialist task

    3) any device that can be accessed over the internet is also open to hackers viruses and so on