Browse Prior Art Database

Common Line Control for Buffered and Unbuffered Terminals

IP.com Disclosure Number: IPCOM000077089D
Original Publication Date: 1972-Jun-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 2 page(s) / 13K

Publishing Venue

IBM

Related People

Broadhurst, D: AUTHOR

Abstract

A common-line control for both buffered and unbuffered terminals that transmit and receive serial data is described. The common-line control for both buffered and unbuffered serial transmission terminals is achieved by making the line control transparent to the device control. This enables the device to be controlled and to be operated independent of the line control. Thus, the device may be buffered or unbuffered, it may operate synchronously and it may be attended or unattended by an operator.

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Common Line Control for Buffered and Unbuffered Terminals

A common-line control for both buffered and unbuffered terminals that transmit and receive serial data is described. The common-line control for both buffered and unbuffered serial transmission terminals is achieved by making the line control transparent to the device control. This enables the device to be controlled and to be operated independent of the line control. Thus, the device may be buffered or unbuffered, it may operate synchronously and it may be attended or unattended by an operator.

A serial synchronous line control is superior to other line controls for most serial transmission devices. It provides for optimum efficiency, speed range, flexibility and reliability. Good efficiency is achieved, since a relatively small amount of information is required for framing, i.e., only messages are framed, character framing is not required.

Since the speed of a synchronous transmission link is determined by a clock, it is only necessary to adjust the speed of the clock to achieve different transmission speeds. Synchronous clocking techniques not only can be used for very low speeds but are indispensable for the high speeds that are used in voice band and the wider bandwidth facilities. Thus, synchronous clocking techniques can be employed over a wide-speed range.

Since a buffered device can be operated at the same fixed speed as the synchronous line, the clocks that control the flow of information over the link are also used to control the transmission of information into or out of the buffers. The buffer operations are, in effect, synchronized with the link operation. Buffered devices are thus naturally suited to serial synchronous line control.

As most unbuffered communications devices operate asynchronously...