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Related to input/output: I/O


[′in‚pu̇t ′au̇t‚pu̇t]
(computer science)
Pertaining to all equipment and activity that transfers information into or out of a computer. Abbreviated I/O.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.


(programming, operating system)
(I/O) Communication between a computer and its users, its storage devices, other computers (via a network) or the outside world. The devices the computer uses to do this are called "peripherals". What actually counts as I/O depends on what level of detail you are considering, e.g. communication between processors would not be considered I/O when considering a multiprocessor as a single system.

Important aspects of I/O are throughput, latency, and whether the communications is synchronous or asynchronous (using some kind of buffer).
This article is provided by FOLDOC - Free Online Dictionary of Computing (


(1) See information operations.

(2) (Input/Output) The transfer of data between the computer's CPU and a peripheral device. Every transfer consists of input and output operations; hence the term "I/O." A transfer is either output from the CPU and input to the peripheral or output from the peripheral and input to the CPU. See PC input/output.

PC input/output

Every peripheral device (keyboard, modem, monitor, etc.) requires a control circuit that interfaces with the computer's processor (CPU). These circuits are either built into the chips on the motherboard or are contained on plug-in cards. See chipset.

On the Motherboard
A fully equipped PC motherboard has built-in controller circuits for all the basic peripheral devices. It has sockets for the internal drives (hard disk and CD/DVD) and ports for external devices: keyboard, mouse, speakers, etc. The motherboard typically also provides built-in circuitry for the monitor and network.

Via Plug-In Cards
Additional input/output can be added by plugging in controller cards into the motherboard's PCI or PCI Express slots. For example, a higher-quality graphics card can be plugged in, and the built-in circuit can be disabled. See PCI and BIOS.

Peripheral Drivers
All peripherals require driver software, which enables the OS to command the hardware. When a peripheral device is added that is new to the computer, a controller card is plugged in, and a driver is installed.

Peripheral Drivers
All peripherals require driver software, which enables the OS to command the hardware. When a peripheral device is added that is new to the computer, a controller card is plugged in, and a driver is installed.

Legacy Interfaces
These peripheral interfaces were found on earlier PCs. If a device requires a mouse, keyboard or serial port, adapters are available that convert them to USB. See legacy port.
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