gcse.compt.sci.computer.systems.u4

• Logic circuit?

  Chains of logic gates
• Embedded Systems?

  • Computer systems that perform a limited number of dedicated functions
  • Usually part of a larger mechanical or electrical system
• Advantages of embedded systems:

  • Highly efficient at limited number of funcions
  • Extremely reliable
• Examples of embedded systems:

  • Fridge
  • Camera
  • Kettle
• General purpose systems:

  • Computer systems that can be programmed to perform a large variety of functions
• Advantages of general purpose systems:

  • Highly versatile - allow large number of input/output devices to be connected
  • Allows software to be installed/updated/removed
• Disadvantage of general purpose systems:

  • Not often fully optimised to perform individual functions
• Examples of general purpose systems:

  • Laptop
  • PC
• Hardware:

  • Physical components of a computer system
• Peripherals:

  • Hardware components not part of the core computer (monitor)
• Input devices:

  • Pass data into system
  • Keyboard, mouse
• Output devices:

  • Pass data out of the system
  • Speaker, monitor
• Software:

  • Programs stored on and run by a computer system
• Categories of software:

  • System
  • Application
• Categories of system software:

  • OS
  • Utility programs
• Application software?


  Software designed for end user to carry out specific functions
• Examples of application software?

  Spreadsheet software

  Presentation software

  Video games
• System software?

  Controls and maintains the operation of a computer system
• Operating system?


  Provides a platform for application software to run on.

  Allows application software to interact with hardware.
• Utility programs?


  Designed to help maintain, optimise, analyse, or configure a computer system
• Antivirus software:

  • Detects and removes malware
  • Prevents a computer system being infected with malware
• OS - Processor management:

  • Functionality of OS which decides the order in which processes have access to the processor and how much processing time each process has
• OS - Memory management:

  • Handles/manages main memory
  • Moves processes back and forth between main memory and secondary storage during execution
• OS - Input/output management:

  • Keeps track of all input/output devices connected to the computer system via the input/output controllers
  • Manages the device drivers for input/output devices
• OS - Storage management:

  • Provides access to and keeps track of files and programs stored on a computer system's secondary storage
• OS - Application management:

  • Interacts with application software
  • Allowing application software to be installed, executed, updated, and uninstalled
  • Allows data for application software to be saved and deleted
• OS - Security management:

  • Protects a computer system's resources form being stolen, edited or deleted
• High level languages:

  • Designed for the programmer
  • Uses phrases similar to the english language
• Advantages of high level languages:

  • Programs are simple to read, write, maintain, and debug
  • Non processor specific
• Disadvantages of high level languages:

  • Less memory efficent
  • Executes slower
• Source code:

  • High level language
  • Examples - Python, C#, Java
• Low level languages:

  • Designed for efficient use of machines architecture
• Advantages of low level languages:

  • More memory efficient and execute faster than high level
  • Processor specific - provide programmer complete control over a machine's specific hardware components
• Disadvantages of low level languages:

  • Complex to read, write, maintain, and debug
  • Processor specific - can only be executed on the specific machine architecture the program has been written for
• Interpreter:

  • Translates and executes each line of source code individually
  • Upon detection of error will immediately stop and inform the programmer where the error was found
• Interpreter advantage:

  • Requires less memory than compiler
• Interpreter disadvantage:

  • Must be installed on all computer systems
• Compiler:

  • Translates entire source code into an object code executable
  • Upon syntax detection, will continue translating and inform after translation
• Compiler advantage:

  • Shared easily
• Compiler disadvantage:

  • Will translate whole code before informing of error