Operating System
Core piece of software that allows the computer to run

Manages:
Hardware
User Interface
All other software

Common features
Providing a user interface
Managing computer memory
Managing computer hardware

6 types of OS
Single user
Multi user
Interactive
Real time
Batch
Distributed

Single user
Two types of single user IS
Single user, single app
Single user, multitasking

Single user single app
Deals with one user, running one application at a time
Eg. Mobiles

Single user, multi tasking
Deals with a single user but can run many apps at the same time
GB of ram available to run multiple applications
Eg. Most personal computer os

Adv of single user, single app
Faster to access as only one user is using the one app

Adv of single user, multi tasking
Can run many application at one time so can easily switch between them

Disadv of single user
Only one user can use the application at one time

Multiuser

The computer has to be shared amongst many users

The OS makes max use of each machine connected to it

OS manages:
Each user logged onto a workstation connected to it
Allocate resources to the jobs they want to run
Manage the processing times and resources used
Manage efficient use of computer processing cycles
Maintain security

Adv
Can share resources such as printers
Centralised back up

Disadv
Viruses can spread across whole network easily
If central server goes down access to network is lost

Interactive
Allows the user to directly interact with the OS whilst programs are running

There will be a user interface allowing users to interact this could be a
CLI or GUI.

Adv: CLI uses less memory to operate
GUI can be used by any person

Dis: CLI: Need to know commands
GUI is memory intensive

Real Time
Commonly known as embedded computers

Designed to handle input data with a certain time

Programmer can prioritise certain tasks whereby the most important signals are processed first, this is know as priority interrupts

Adv: Effective as there is task scheduling

Disadv: Need experience and expertise

Batch
Used to run jobs without user interaction.
Job set of input data files to be processed at a later time

Result may be a set of output files/printed documents

Eg. Payroll systems
Adv: Only have to program once
Disadv: Need to know the system
:If error occur have to reprogram

Distributed
Form of parallel processing
Single task is broken down into smaller tasks
Results are then gathered together
The OS manages this task
A render farm is used to carry out this type of processing

Eg CGI or animation
Render farm: Large collection of computers networked together and controlled by the OS. Individual