Quick Reference

1 In telecommunications in general, a separate path through which signals can flow.

2 In the public switched telephone network (PSTN), one of multiple transmission paths within a single link between network points.

3 In mainframe parlance, a specialized processor that comprises an information route and associated circuitry to control input and/or output operations. It normally provides for formatting and buffering and has the necessary control to meet the timing requirements of an I/O device.

Several different I/O devices may be connected to one channel and the control circuitry within the channel directs the data streams to or from the appropriate device. If the I/O devices have a relatively slow data rate, then a multiplexer channel is used in which transfers to or from the separate devices are interleaved, character by character, such that several devices can work simultaneously.

When a number of devices with high data rates, e.g. magnetic disk and tape, are to be connected, a selector channel is used. This will transfer a complete record to or from a device before reselecting.

A channel is often a wired-program processor. As channels have become more elaborate they have tended to become programmed computers (I/O processors) in themselves. See also peripheral processor.

4 A gray-scale digital image equivalent to one of the components of a color image. For example, an RGB image consists of red, green, and blue channels.

5 On the World Wide Web, a pre-defined web site that can automatically send updated information for immediate display or viewing on request.

6 In computer marketing, a “middleman” between a product creator and the marketplace. This is distinct from direct selling where the manufacturer sells directly to the end user. Value-added resellers (VAR) and retail store chains are examples of channels in this context.

7 In a field-effect transistor (FET), the path in the semiconductor through which current flows.

Subjects: Computing.

Reference entries