Backing Storage

1
Input Devices
Touch Screen
Backing Storage Devices
Main Memory
CPU
ROM
RAM
Output Devices
Plotter
2
Input Devices
Backing Storage Devices
Main Memory
CPU
ROM
RAM
Output Devices
3
Main Memory
RAM
ROM

• RAM RANDOM ACCESS MEMORY
• Memory which you can read from and write to
• Stores data and programs temporarily, when
  computer is switched off anything stores in RAM
  is lost

• ROM READ ONLY MEMORY
• Memory which you can store data and programs
  permanently
• ROMs contents are not lost when you turn the
  computer off
• ROM is used to store the program you use when you
  first start the computer (eg Microsoft Windows)

4
Input Devices
Backing Storage Devices
Main Memory
CPU
Output Devices
5
Backing Storage Devices

• Hard disc - stores a huge amount of information
  and can be accessed quickly
• Floppy disc - only stores 1.4 Mb but it is
  portable

6
Backup copies

• What is a backup copy?
• Another copy of the files that is made regularly
  and kept in a safe fireproof place
• Why is it needed?
• Incase the original file is lost of damaged.

7
What type of backup media should we use?

• What type of media would you use to back up one
  small file -
• a floppy disc
• What about backing up our network file server
  (its got several hard discs and Gigabytes of
  data) -
• Tape
• What about a PC - Zip drive or Jazz drive or CD
  Writer

8
Why use tapes to backup a file server?

• How much data can a tape back up?
• a huge amount of data - our tape can hold the
  contents of 5 hard discs
• How fast is it to use a tape?
• slower than disc to get information from as it is
  accessed sequentially
• Does the speed matter?
• No - its only used in an emergency!