Operating system and system software Operating Systems
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- Boot Sequence
- Process
- Time-sharing between process A and process B
Boot loader: Program in ROM (example of firmware) Run by the CPU when power is turned on Transfers operating system from mass storage to main memory Executes jump to operating system
Process (Application) Management Process: The activity of executing a program Process State: Current status of the activity Program counter General purpose registers Related portion of main memory Scheduler: Adds new processes to the process table and removes completed processes from the process table Dispatcher: Controls the allocation of time slices to the processes in the process table The end of a time slice is signaled by an interrupt.
Efficient Allocation Of Resources The operating system ensures that Multiple tasks of the computer can be underway at one time Processor is constantly busy Keeps a queue of programs that are ready to run Whenever processor is idle, picks a job from the queue and assigns it to the processor Semaphore: A “control flag” Critical Region: A group of instructions that should be executed by only one process at a time Mutual exclusion: Requirement for proper implementation of a critical region The Safe Use Of Resources Deadlock Two processes are each holding a resource the other needs Neither process will ever progress The operating system must handle deadlocks Deadlock prevention Deadlock recovery
System Security And Protection The operating system must prevent Non-authorized people from using the computer User names and passwords Legitimate users from accessing data or programs they are not authorized to access Authorization lists Directory: slupoli -> notes notes -> Bash script with various commands notes -> Basic Computer Terminology Download 0.94 Mb. Share with your friends:
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