The expansion bus connects slower low-bandwidth devices, which typically deliver data one character at a time ( with buffering. ).The PCI bus connects high-speed high-bandwidth devices to the memory subsystem ( and the CPU. ).Figure 13.1 below illustrates three of the four bus types commonly found in a modern PC:.Buses include rigid protocols for the types of messages that can be sent across the bus and the procedures for resolving contention issues.A common set of wires connecting multiple devices is termed a bus.Devices connect with the computer via ports, e.g.Devices communicate with the computer via signals sent over wires or through the air.I/O devices can be roughly categorized as storage, communications, user-interface, and other.Device drivers are modules that can be plugged into an OS to handle a particular device or category of similar devices.I/O Subsystems must contend with two ( conflicting? ) trends: (1) The gravitation towards standard interfaces for a wide range of devices, making it easier to add newly developed devices to existing systems, and (2) the development of entirely new types of devices, for which the existing standard interfaces are not always easy to apply.( Consider the range of devices on a modern computer, from mice, keyboards, disk drives, display adapters, USB devices, network connections, audio I/O, printers, special devices for the handicapped, and many special-purpose peripherals. Management of I/O devices is a very important part of the operating system - so important and so varied that entire I/O subsystems are devoted to its operation.Abraham Silberschatz, Greg Gagne, and Peter Baer Galvin, 'Operating System Concepts, Eighth Edition ', Chapter 13 13.1 Overview.Operating Systems: I/O Systems I/O Systems References: Best Answer: There are two kinda processing.Serial and Parallel.In serial processing the cpu gets the info, analyse it, process it, send it as output and all these functions are done in a sequential manner, that is, only one job is done at a time and only on the completion of that job the other job starts.
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