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Browse Prior Art Database

Switching Control for Integrated Computer Network

IP.com Disclosure Number: IPCOM000074262D
Original Publication Date: 1971-Apr-01
Included in the Prior Art Database: 2005-Feb-23
Document File: 5 page(s) / 68K

Publishing Venue

IBM

Related People

Fredericksen, DH: AUTHOR [+8]

Abstract

This description relates to a switching control and express interpreter (SCEI) in an integrated computer network.

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 34% of the total text.

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Switching Control for Integrated Computer Network

This description relates to a switching control and express interpreter (SCEI) in an integrated computer network.

The SCEI, or switch, functions as a store and forward message hand-device and as an interface with the rest of the network machine and network machine operating system. It is an autonomous unit and is capable of handling explicit requests for message transmission by itself.

In Fig. A, there is schematically depicted the functional units with which SCEI interfaces. It is seen therein that SCEI interfaces with the operating system, various access methods to I/O units, and the individual user nodes (UNs). It sends data from user node (UN) to user nodes (UN) via a communications grid, receives inquiries from UNs and responds to them. It also interfaces with the network operating systems. The SCEI is able to decode a message from any interface and determine to what other interface the message should be sent.

The SCEI is operative in an integrated computer network which has the following operating characteristics:

1) The network utilizes binary synchronous communications (BSC).

2) The network operates in the "contention" node rather than by "polling" by a master control. (in the case of simultaneous contention, the grid node (GN) will have SEND priority and the user node (UN) will switch to RECEIVE).

3) Communication lines are half-duplex.

4) Lines can be leased or switched.

5) Available bandwidth is from 2KB to 40.8KB.

6) All transmission from the SCEI to user nodes and vice versa is in transparent mode.

7) Standard B/SC control characters are employed wherever possible.

8) Basic telecommunications access method (BTAM) conversational mode is employed.

9) All transmission blocks have the format shown in B.

The primary function of the network is to deliver messages from one node to another. In order to perform this function and to collect audit information, a communication header is attached to each physical block of data handled by the network. A block has a maximum size (such as 1065 bytes, for example) including B/SC control characters, header and text. Figs. C and D show the fields within a header and their respective purpose and selection rationales are further explained hereinbelow. BI-SYNC Control Characters.

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The BI-SYCN control characters DLE (data link escape) and STX (start of text) precede each block of data flowing within the network. This pair of characters informs the receiving station that the block of text has been transmitted in the transparent mode. Action Code.

This code selects the immediate destination of the transmitted blocks. The data may be transmitted directly to the user, sent to the network operating system, or used by the SCEI. Initially, any conflict in information between this field and any other field in the header causes an error message to be returned to the originating station and, thereafter, the network operating system may at...