Operating Systems

System programs are programs that manage the operation of a computer.

The Operating system is the most fundamental of all the system programs.

Without it the computer is basically a useless collection of metal, silicon and plastic.

An Operating system has these roles:

• Hides the complexities of the hardware from the user (Virtual machine)
• Manages the file system
• Manages Proceses
• Manages Security
• Manages Internet and network connections
• Manages RAM and Virtual Memory

The Operating system hides the complexities of the hardware from the user, and in doing this creates a virtual machine.

A virtual machine is the apparent machine that the operating system presents to the user, achieved by hiding the complexities of the hardware behind layers of operating system software.

Operating systems are designed for different purposes.

Many things in your house will have an operating system, even if you dont intract with it yourself.

Most Operating syststems are made up of parts of these different categories.

• User Interacts directly with the system

• User supplies commands and data

• Results are given to the User Immediately

• The User and the computer are in two-way communication

• Actively monitoring something

• Output is result of inputs

• Monitoring multiple inputs

• e.g. Eden project, Temperatures measured and Outputs control environment

• Layer of software added to the OS

• Allows computer to be conected to a network

• Intercepts all commands that reference netwrok reasources

• Specialised service to machines on network

• File Servers, Domain Control, Print Servers

• Optimised for its purpose. Less gerneral-purpose processing

• General Purpose, must support broad range of tasks

• modular fashion (You can enable/disable parts of the OS)

• Need large ammounts of memory

• Windows Xp and 7 are exaples of Desktop Operating Systems

• The Operating System is within a larger device

• Inputs are from sensors

• Does not usually have a User Interface

• Examples are Microwaves, Televisions, Ovens, Cars

• Operating Systems within Phones, Mobiles, PDA's , MP3 players

• Work in real time

• Processing power is limited

• Power Consumption must be considered when creating mobile Operating Systems