Device controller and CPU can work concurrently. All Devices like Hard disk, magnetic disks, Printers, Memory are dumb, means they won't work with out device controller.
If i want to read some file from Disk , Disk controller reads the data from disk to Disk controller buffer then it transfer to main memory. Then user is able to read the file.
CPU is processing process p1, in process p1 there is an instruction 'read opd.txt file'. then CPU gives this request to Device controller (disk controller) then disk controller is reading the data from disk mean wile CPU should not Idle and CPU context switching to process p2 and process p1 is preempted . This is Called Context switching.
If i want to read some file from Disk , Disk controller reads the data from disk to Disk controller buffer then it transfer to main memory. Then user is able to read the file.
CPU is processing process p1, in process p1 there is an instruction 'read opd.txt file'. then CPU gives this request to Device controller (disk controller) then disk controller is reading the data from disk mean wile CPU should not Idle and CPU context switching to process p2 and process p1 is preempted . This is Called Context switching.
1 comment:
good
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