Peripheral: Difference between revisions
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They are usually attached to a computer to pass data in and out of the computer - either to [[secondary storage]] which is permanently accessible; some other form of data storage, intended for off-line storage (e.g. [[magnetic tape]]); or communication, either to [[user]]s or other computers, etc. A few device types (such as [[real-time clock]]s) perform non-[[input/output|I/O]] functions. | They are usually attached to a computer to pass data in and out of the computer - either to [[secondary storage]] which is permanently accessible; some other form of data storage, intended for off-line storage (e.g. [[magnetic tape]]); or communication, either to [[user]]s or other computers, etc. A few device types (such as [[real-time clock]]s) perform non-[[input/output|I/O]] functions. | ||
Devices may use either [[programmed I/O]] or [[Direct Memory Access|DMA]] to get data in and out of the [[Central Processing Unit|CPU]] and/or [[main memory]], and [[interrupt]]s to get the CPU to pay attention to the device when needed. | Devices (or, more accurately, their controllers) may use either [[programmed I/O]] or [[Direct Memory Access|DMA]] to get data in and out of the [[Central Processing Unit|CPU]] and/or [[main memory]], and [[interrupt]]s to get the CPU to pay attention to the device when needed. | ||
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Revision as of 15:03, 7 October 2018
A peripheral or device is a separate mechanism (always including some electronic hardware, but often also some mechanical constituents) attached to a computer. They are often divided into the actual device, and a device controller which is directly attached to the computer, and mediates between it and the actual device.
They are usually attached to a computer to pass data in and out of the computer - either to secondary storage which is permanently accessible; some other form of data storage, intended for off-line storage (e.g. magnetic tape); or communication, either to users or other computers, etc. A few device types (such as real-time clocks) perform non-I/O functions.
Devices (or, more accurately, their controllers) may use either programmed I/O or DMA to get data in and out of the CPU and/or main memory, and interrupts to get the CPU to pay attention to the device when needed.
