self doubt

Question

Difference between  both synchronous and asynchronous I/O on the based of ISR . Means when they are going to invoked during i/o completion  ( i.e. before, after ?????? )

Answer 1

Synchronous I/O device and processor work in one time. So, processor(which process ISR too) need to wait after requesting a task.Synchonous IO is depend on synchronous clock. So, many routing and program depends on it. Here clock rate and bus length inversely proportional.

In asynchronous i/o user (device) and kernal(processor) work separately. So, no need to wait for processes as they are always ready in job queue. It doesnot depend on clock rate. Example of asynchronous IO operates on USB, Firewall

https://www.geeksforgeeks.org/gate-gate-cs-2008-question-64/

Comments

srestha mam 

1st statement of both clear i.e synchronus means someone monitoring him . asynchronus no one so...

2nd statement in case of asynchronus fine , asynchronus all clear concept

now come to synchronus  u r saying processor need to wait after requesting a task ( interrupt ) okkk.i think maybe it should be i/o need to wait after request interrupt .as processor doing its work , interrupt comes . it will do its work up to clock .and next clock it see interrupt . so i think that line should be modifies up to some extent 

otherwise solution is fine and my doubt is actually to asynchronus which is cleared.

thanku :) for that

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CPU  waits for io signal

look at the link

it is written

but it should be made possible for the cpu to wait or to check regularly, while actually performing lots of other tasks and only going back to the IO process when it's ready

https://softwareengineering.stackexchange.com/questions/296709/why-do-we-have-to-wait-for-i-o

 

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chk these links too

https://www.cs.uic.edu/~jbell/CourseNotes/OperatingSystems/13_IOSystems.html

https://stackoverflow.com/questions/35012494/difference-between-synchronous-and-asychnchronus-i-o