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.
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Main Roles of an Operating System
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
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Virtual Machines
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.
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Different Types of Operating System
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.
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Interacive Operating Systems
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
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Real-time Operating Systems
Actively monitoring something
Output is result of inputs
Monitoring multiple inputs
e.g. Eden project, Temperatures measured and Outputs control environment
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Network Operating Systems
Layer of software added to the OS
Allows computer to be conected to a network
Intercepts all commands that reference netwrok reasources
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Server Operating Systems
Specialised service to machines on network
File Servers, Domain Control, Print Servers
Optimised for its purpose. Less gerneral-purpose processing
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Desktop Operating Systems
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
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Embedded 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
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Moblie device Operating Systems
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
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