Operating System Short notes

 Operating System 

An interface between computer and user 

Operating System Management  Tasks 

1. Processor management (convert process into a man gable size and given to CPU)
2. Memory Management (RAM (data coordination and check virtually memory is need or not))
3. Device Management( an interface b/w connected device)
4. Storage Management (direction for permanent data)
5. Application (standard computer communication with software)
6. User interface (Communication with user)

Functions of Operating System

1. Booting (it Boots the Computer)
2. User interface command line
3. Graphical user interface 
4. Handling resources (Memory and peripheral Resource management)
5. File Management (Store data and retrieve)
6. Error management(Take maximum preventive methods to avoid errors)

Types of Operating System

1. Simple Batch System ( There is no interaction b/w user and computer) . Giving jobs through card , tape etc.There is no mechanism to prioritize the process
2. Multi Programming batch system (running other job with currents job ) CPU Always engaged .CPU never be idle (maximize the cpu usage )
3. Time sharing system (minimizing the response time)
4. Multiprocessor (several processor with common memnory )(Higher computing power and speed ). System divides in to many task and parallel it executes in many processors  but use single os
5. Desktop system (users covinence)
6. Distributed operating system Low Price . Client server system . PEER to PEER (WWW)
7. Clustered system (LAN network )each node monitor other node if one fails other will take charge and run . Asymmetric clustering e (hot stand by =host : monitor the active server). Symmetric (Two or more host and monitor each other)
8. Parallel Clustures multiple hosts can access shared data
9. Real time operating systems i) hard real time operating systems  ii)soft real time systems
10. Hand held systems (Cellular phones)

 Process

A program in execution 

Process memory divided into 4 sections

1. Text section (compiled program codes)
2. Data section (global and static variables)
3. Heap (loop, malloc)
4. Stack (local variables)

Process state 

new 

Ready (waiting to next process)

running

wait 

terminates

Process control block 

 information about all process 

  Process state(running,ready ,wait)

  Process id

CPU registers and program counter(address of next instruction)

memory management information (page table )

accounting information

i/o status information