KEY CONCEP'IS
o
Procesa
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| Peripheral Subayatem |
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Service
Order
Messaqe
Device | (:;'\ | |
Task | - V | |
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Service
Reply
Message
O.Process running on GDP needs I/O service
1.Process formulates message describing service, sends it to device task
2.Device task receives service order, interprets it
3.Device task transfers data according to service order parameters
4.Device task formulates reply message containing result of transfer operation, sends it back to originating process.
5.Originating process receives reply, interprets it, executes accordingly
