2b Operating Systems

2b Operating Systems

1. Roles

   • Deals with security and passwords
   • Responds to user input
   • Manages computer system
   • Opens and saves files
   • Allocates memory to applications
   • Communicates with hardware (using drivers)
   • Prioritises processes.

2. Single User

   • Only one user can use the computer system (processor) at a time.
   • There can be multiple user ACCOUNTS but they can't be used simultaneously.
   • e.g. A stand alone computer with no network connection

3. Multi-user

   • Can be used by more than one user at a time
   • e.g. Can refer to a networked server with many devices connected
   • e.g Can be a mainframe computer with many terminals
   • Roles
     • Manage log-ons and permissions
     • Allocate jobs
     • Allocate memory to each user.

4. Multi-tasking

   • Can process more than one task at the same time
   • e.g. word processor being opened while a document is printing
   • Fast single processors can use scheduling to seem like their are multi-tasking
     • Seems like multitasking
   • Processors with multiple cores of systems with more than one processor can really multi-task

5. Distributed processing

   • Processes using several processors from several computers usually in different locations
   • Computers need to be networked LAN or WAN
   • Every computer has its own processor and memory
   • One computer (usually a server) acts as co-ordinating device
     • Server assigns tasks to other processors
       • Result gathered by co-ordinating device to produce final output
   • Processing takes place when other processors are idle from normal task e.g. at night
   • e.g multi-player games or research applications