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Operating System Overview Presentation Transcript:
1.Operating System Overview - 2
2.Operating System
A program that controls the execution of application programs
An interface between applications and hardware
3.Convenience
Makes the computer more convenient to use
Efficiency
Allows computer system resources to be used in an efficient manner
Ability to evolve
Permit effective development, testing, and introduction of new system functions without interfering with service
4.Layers of Computer System
5.Kernel
Portion of operating system that is in main memory
Contains most frequently used functions
Also called the nucleus
6.Evolution of an Operating System
Hardware upgrades plus new types of hardware
New services
Fixes
7.Evolution of Operating Systems
Serial Processing
No operating system
Machines run from a console with display lights, toggle switches, input device, and printer
Schedule time
Setup included loading the compiler, source program, saving compiled program, and loading and linking
8.Simple Batch Systems
Monitors
Software that controls the sequence of events
Batch jobs together
Program branches back to monitor when finished
9.Special type of programming language
Provides instruction to the monitor
What compiler to use
What data to use
10.Hardware Features
Memory protection
Do not allow the memory area containing the monitor to be altered
Timer
Prevents a job from monopolizing the system
11.Privileged instructions
Certain machine level instructions can only be executed by the monitor
Interrupts
Early computer models did not have this capability
12.Memory Protection
User program executes in user mode
Certain instructions may not be executed
Monitor executes in system mode
Kernel mode
Privileged instructions are executed
Protected areas of memory may be accessed
13.Uniprogramming
Processor must wait for I/O instruction to complete before preceding
14.Multiprogramming
When one job needs to wait for I/O, the processor can switch to the other job
15.Time Sharing
Using multiprogramming to handle multiple interactive jobs
Processor’s time is shared among multiple users
Multiple users simultaneously access the system through terminals
Operating System Overview Presentation Transcript:
1.Operating System Overview - 2
2.Operating System
A program that controls the execution of application programs
An interface between applications and hardware
3.Convenience
Makes the computer more convenient to use
Efficiency
Allows computer system resources to be used in an efficient manner
Ability to evolve
Permit effective development, testing, and introduction of new system functions without interfering with service
4.Layers of Computer System
5.Kernel
Portion of operating system that is in main memory
Contains most frequently used functions
Also called the nucleus
6.Evolution of an Operating System
Hardware upgrades plus new types of hardware
New services
Fixes
7.Evolution of Operating Systems
Serial Processing
No operating system
Machines run from a console with display lights, toggle switches, input device, and printer
Schedule time
Setup included loading the compiler, source program, saving compiled program, and loading and linking
8.Simple Batch Systems
Monitors
Software that controls the sequence of events
Batch jobs together
Program branches back to monitor when finished
9.Special type of programming language
Provides instruction to the monitor
What compiler to use
What data to use
10.Hardware Features
Memory protection
Do not allow the memory area containing the monitor to be altered
Timer
Prevents a job from monopolizing the system
11.Privileged instructions
Certain machine level instructions can only be executed by the monitor
Interrupts
Early computer models did not have this capability
12.Memory Protection
User program executes in user mode
Certain instructions may not be executed
Monitor executes in system mode
Kernel mode
Privileged instructions are executed
Protected areas of memory may be accessed
13.Uniprogramming
Processor must wait for I/O instruction to complete before preceding
14.Multiprogramming
When one job needs to wait for I/O, the processor can switch to the other job
15.Time Sharing
Using multiprogramming to handle multiple interactive jobs
Processor’s time is shared among multiple users
Multiple users simultaneously access the system through terminals
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