1.1 System Architecture (Version 2)

1.1 System Architecture (Version 2)

1. Embedded System

   • A computer system within another device
   • To provided specific pre-defined functions
   • Examples
     • MP3 Player
     • Sat Nav
     • Mobile Phone
     • Dishwasher
   • Known as Firmware
     • Made of Hardware and software
   • Used for speciallised tasks

2. Control Unit

   • Controls flow of data within the CPU

3. Cache

   • Frequently used instructions and data done simultaneously
   • A bigger cache size = more space for frequently used data simultaneosly
     • Reduces number of memory to disk transfer
     • May speed up the processing stage of the instructions
   • Part of the CPU
   • Acts as an intermediary between the CPU and Main Memory

4. Hertz

   • Number of cycles per second.
   • GHz
     • One billion instructions executed per second.
   • MHz
     • One million instructions executed per second

5. Execute

   • To carry out the instructions.

6. Clock speed

   • The number of instructions per second
   • Doubling this will increase the number of instructions per second
   • Measured in Hertz

7. Instructions

   • Information on how to operate, perform or to maintain software or hardware.

8. Core

   • Increasing the number of cores will increase the number of instructions carried out
     • E.g. 2 cores may double the amount
   • Where instructions are executed
   • Part of the CPU

9. Processor or CPU (Central Processing Unit)

   • Used to fetch data, decodes data and to execute data (FDE)
   • Brains of the computer
   • Processes data
   • Contains a clock speed
     • A faster clock speed = More inctructions executed

10. Main Memory

    • RAM
    • ROM
    • EEPROM

11. System Buses

    • Address Bus
      • Uni-Directional (One way)
      • Data and instructions are returned to the bus
      • Carries addresses from CPU to Mian Memory or I/O devices
    • Set of parallel wires connecting 2 or more independent components to pass signals between them
    • Data Bus
      • Bi-Directional (Two way)
      • Data can be written/read
      • Carries data/instructions from Main Memory to CPU (or any secondary storage device)
    • Control Bus
      • Instructs ,which was, data will be travelling to/from memory
      • Control signals are sent with this
        • Memory read
        • Memory write