The Operating System Flashcards
Batch Operating Systems
Processes large amounts of data in batches
How do batch operating systems work
Batch’s of data are sent to the CPU to be processed
What is one advantage of batch operating systems
They are designed to handle large amounts of data at once quickly
What is one disadvantage of batch operating systems
They have limited use with complex problems
Single-user operating systems
Allows only one user to operate the system at any one time
How do single user operating systems work
They limit the instructions that can be processed so that only one person can enter them
What is one advantage and one disadvantage of Single-user OS
Advantage: Fast and efficient for problems encountered by one user.
Disadvantage: Not fast for dealing with large amounts of data, due to a lack of processing power
Multi-user OS
Allows multiple users to access one operating system at the same time
How do Multi-user OS work
Processes all of the users instructions and problems using more processing power, therefore making it more efficient
What is one advantage and one disadvantage of Multi-user OS
Advantage: Can share data easily between multiple users
Disadvantage: Not suited to smaller tasks, as it wastes processing power
Multi-tasking OS
Supports the ability to completed multiple tasks at the same time
How do multi-tasking OS work
They Process multiple tasks at the same time on different cores.
What is one advantage and one disadvantage of Multi-Tasking OS
Advantage: Allow the processing of multiple tasks
Disadvantage: is more expensive, and can loose smoothness if one operation slows the system down
Multi-programming OS
Optimizes use of the CPU, preventing it from ever being idle
How do Multi-programming OS work
Stores multiple jobs in the computers main memory at the same time, processing them each time the CPU is available
What is one advantage and one disadvantage of Multi-Programming OS
Advantage: Makes processing smooth and feel like multiple programs are being processed at the same time
Disadvantage: Takes lots of memory, and can be slowed down by one large important task.
Time sharing
Allows multiple users to share computers simultaneously
Interrupts
A signal to the processor initiated by a program or device that temporarily stops the current processes to tell the processor to execute another task
Processes
An instance of a program that is currently being executed, made of threads
Threading
Each thread handles a separate sequence of tasks
Multitasking
The appearance of multiple tasks being completed at the same time
Shceduler
Decides which process will be executed next and the length of time that process will have to be executed for
What are the three states in the scheduler
- Ready to run
- Running
- Blocked
Explain the state, Ready to run
Scheduler decides where the process will be placed within the ready to run queue
Explain the state, Running
The process is within the CPU being Run
Explain the state, Blocked
The process is waiting for an input/output operation for it to continue
What are the five different Scheduling processes
- First Come First Served
- Shortest job first
- Shortest time remaining
- Round Robin
- Multi-level feedback queues
First come first serve
Processes are dispatched according to their arrival time on the ready queue
First come first server, advantages and disadvantages
Simple to implement
Long processes can hog the CPU, Leading to a low throughput
Shortest job first
Prioritizes the jobs that take the shortest amounts of time
Shortest job first, advantages and disadvantages
Minimizes the average waiting time
Generates starvation, so can have extremely long turn around times
Shortest remaining time
Prioritizes the process with the shortest amount of time left to execute
shortest remaining time, advantages and disadvantages
Reduces the number of pre-emption’s
Fails, when the process time is unknown before hand
Round Robin
Randomly selects the process that is next to be run from the list of processes
Round Robin, advantages and disadvantages
Doesn’t face the issue of starvation
No priority for important tasks
Multi-level feedback queues
Sorts the process into different queues with different priorities which it then takes from when available space is opened up in the CPU
Multi-level feedback queues, advantages and disadvantages
Allows for process prioritization and aging
Requires a very complex algorithm to run
