How an I/O operation is handled by the system with the help of diagram
Answers
I/O devices can be roughly categorized as storage, communications, user-interface, and other
Devices communicate with the computer via signals sent over wires or through the air.
Devices connect with the computer via ports, e.g. a serial or parallel port.
A common set of wires connecting multiple devices is termed a bus.
Buses include rigid protocols for the types of messages that can be sent across the bus and the procedures for resolving contention issues.
Figure 13.1 below illustrates three of the four bus types commonly found in a modern PC:
The PCI bus connects high-speed high-bandwidth devices to the memory subsystem ( and the CPU. )
The expansion bus connects slower low-bandwidth devices, which typically deliver data one character at a time ( with buffering. )
The SCSI bus connects a number of SCSI devices to a common SCSI controller.
A daisy-chain bus, ( not shown) is when a string of devices is connected to each other like beads on a chain, and only one of the devices is directly connected to the host.