| Let us consider how it works
A. From the point of view of the I/O module:
- For input, the I/O module services a READ command from the processor.
- The I/O module then proceeds to read data from an associated peripheral device.
- Once the data are in the modules data register, the module issues an interrupt to the processor over a control line.
- The module then waits until its data are requested by the processor.
- When the request is made, the module places its data on the data bus and is then ready for another I/O operation.
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