Topic 2

Topic 2

1. Secondary storage

   • Secondary storage is non-volatile disk space, and is sometimes called auxiliary memory, secondary memory or external memory.
   • Secondary storage is additional storage facilities added to a computer system to store data and programs when the power to a system is switched off.
   • Most computer systems need secondary storage to store these things.
     • The operating system
     • Any programs or data that the user installs onto their computer
     • Any files or documents containing the users data

2. ROM

   • Not volatile
   • Stores BIOS
   • Stores the operating system
   • 1-2MB
   • Contents cannot be changed
   • EEPROM
   • PROM

3. RAM

   • Volatile
   • Temporally stores modules.
   • Data you are working on
   • Allows you to keep multiple windows open at the same time
   • Runs the operating system
   • 1-4GB
   • Contents can be changed
   • Dynamic RAM
   • Static RAM

4. Input devices

   • Output devices
     • Used to output data to the user
     • Monitor
     • Speakers
   • Used to input data into the computer
   • Keyboard
   • Mouse

5. Input and output devices for special needs

   • People with special needs need different devices so they can use them as well.
   • Braille keyboard
   • Screen readers

6. CPU

   • Executes programs using the fetch execute cycle
   • Has 3 main parts
     • The control unit
     • The arithmetic and logic unit (ALU)
     • Registers

7. Virtual Memory

   • When there is not enough RAM to deal with all the demands on the computer it will use a section of the hard disk as a temporary store for some of the data. This area is known as virtual memory.
   • Virtual memory is much slower than main memory because processing power is being taken up by moving data around, rather than just executing instructions.
   • Using virtual memory slows the computer down because copying to a hard disk takes much longer than reading and writing RAM.