Device Allocation

Devices can be :

• Dedicated : e.g. magnetic tape, terminal, printer - usually allocated for long periods - Only allocated to authorised processes
  OS must decide when to allocate (avoiding deadlock)
  simple policy - open fails if already opened
• Shared : e.g. discs, window terminals.
  OS provides filing system for discs (will cover this later)
• Spooled : e.g printers
  Provide sharing of non-sharable devices !
  Reduce I/O time and increase throughput