can anyone tell me what hardware deals with interuppt signals and how it works, i have a rough idea but not full circle, also pre-emptive multi-tasking has me stumpted??

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Last Post by morb

I guess that this is for some kind of exam.
You have 3 types of transfering from user mode to kernel mode:
- interupptions
- exeptions
- system call

Interuppts are sinchronuos events that OS uses to give aknowledgment of finishing some paticulary event like completion of copy, detection of DVD/CD etc.

Exact procedure, you will need to learn from book.

1) Processor is calling OS on specific adress, and saves supervisor bit and goes to kernel mode
2)Saves minimal context (to remember where the process stoped)
3)Identifies type of device and type of demand
4)Calling the coresponding function
5)After the procedure is finished, loads the state of user application (where is stoped)
6)Resets the supervisor bit, and returns from kernel mode to user mode.
7)Application/process continues where it stoped.

Note: If this is for exam, study it better.

And pre-empted and multitasking is story for themselves.

Pre-empted are algorithm types for organizing CPU time.
Pre-empted->threads/processes that can be interuppted by other thread/process.
Multitasking-> more than one process/thread can work in same time.

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