4.6 Fundamentals of Computer Systems (The Operating System) Flashcards
How does the OS manage the Processor
The OS decides which process to excecute by scheduling, and allocating time for each process, and handles interrupts to the process that is currently being excecuted.
What are Interrupts and how are they managed
- Signals sent to the Processor to request immediate attention.
- When received it suspends the task that it is excecuting and runs the task associated with the interrupt (if it has a higher priority).
- This is used for when immediate tasks like a mouse click must be excecuted ahead of a long list of other tasks.
What is Scheduling
The OS uses algorithms to determine the most efficient order to excecute the processes based on priority, task length, and when the task was requested.
When is Scheduling used
- This is also used for when files from a processs needs to be stored
How does the OS manage memory
The OS records how memory is divided so that memory is allocated efficiently between processes that are running
Name 3 memory management operations the OS conducts
1- tracking the status of memory allocation
2- Determining current storage requirements
3- Controlling memory usage
How does the OS track the status of memory allocation
- naming all of the physical memory slots as “free” initially and when a program is loaded into a memory address, that address becomes “allocated”.
How does the OS determine the storage requirements of a process
- It is rare that a program can fit in one memory location
- So, the reserves memory on the RAM based on the requiremnts of the program (type, length, size)
How does the OS control memory usage
- As more processes occur less memory is free
- The OS manages the swapping between processses and their memeory space on the RAM to provide memory access for other programs
What is virtual memory
- When the OS extends the limited spaace of main memory
- Using secondary storage that reserves memory to act as main memory
How does the OS use Virtual Memory
- It swaps parts of the process that is not currently in use into the virtual memory, then swaps it back when need
What is the disadvantage of using paging or virtual memory
It uses secondary memory that is slower to access and to write to than primary memory.
How does the OS manage I/O devices
The OS takes a requests from the application software and issues the required command to the appropriate device to help complete the task. In order to manage these devices, device drivers are used which contain device specific instructions that the devices use to complete their respective tasks.
How does the OS manage Files/Resources
The OS uses file systems that tracks where files are stored. These file systems include Folders, Directories and files which users use to easily navigate their files.
