Browse Prior Art Database

Outboard Processors for Data Link Control

IP.com Disclosure Number: IPCOM000049651D
Original Publication Date: 1982-Jul-01
Included in the Prior Art Database: 2005-Feb-09
Document File: 3 page(s) / 50K

Publishing Venue

IBM

Related People

Avis, RE: AUTHOR [+4]

Abstract

In the word processing system environment, communication e attachments are highly unique in that they are usually oriented to one type of line discipline, or in order to achieve greater flexibility, they may be required to attach to an external communications controller. These controllers are usually an extra expense and require special supporting programs in the host system. This is a disadvantage to a customer in that not only does extra equipment and programming have to be purchased but the selection of I/O devices is limited due to restrictions placed on the controller. This article describes a communications subsystem controller which is self-contained under the covers of the system mainframe and provides two separate teleprocessing line disciplines which can be used in any combination by the system.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 53% of the total text.

Page 1 of 3

Outboard Processors for Data Link Control

In the word processing system environment, communication

e attachments are highly unique in that they are usually oriented to one type of line discipline, or in order to achieve greater flexibility, they may be required to attach to an external communications controller. These controllers are usually an extra expense and require special supporting programs in the host system. This is a disadvantage to a customer in that not only does extra equipment and programming have to be purchased but the selection of I/O devices is limited due to restrictions placed on the controller.

This article describes a communications subsystem controller which is self-contained under the covers of the system mainframe and provides two separate teleprocessing line disciplines which can be used in any combination by the system.

The two disciplines addressed are binary synchronous communication (BSC) or synchronous data link control (SDLC). The two disciplines can be utilized with modems or by direct linkage. No changes in the controller's microcode are required when using either of these disciplines. The communication subsystem controller is modular in construction, and as more lines are required, components of the same part number may be plugged into the system mainframe.

The subsystem can be divided into multiplexers that communicate with the system port through a common multiplexer that attaches to the same port. Fig. 1 shows basic communication subsystem controller building blocks. One multiplexer 200 can be attached as a controller and can multiplex up to eight separate BSC/SDLC-type line disciplines. In the configuration shown, four line attachment hardware components (0) through (3) can each support two lines.

In the overall configuration shown in Fig. 2, CSM 0 (100) can support not only six more multiplexers (200) through (300) with identical hardware as itself, but can also support a complement of eight lines of its own.

Although the communications subsystem controller is architected for this type of configuration, a more practical maximum configuration is one with three CSMs for a total of 24 communication lines.

The CSMs are microprocessors...