Browse Prior Art Database

Loop Throttling Controls

IP.com Disclosure Number: IPCOM000085441D
Original Publication Date: 1976-Apr-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 3 page(s) / 37K

Publishing Venue

IBM

Related People

Schappe, TL: AUTHOR

Abstract

In a loop communication system of the form suggested schematically in Fig. 1 station P may send unique flag (control) characters. These may be used to delimit data messages originating at P, and also to identify time slots which may be seized (and over-written) by individual secondary stations S for their return transmissions to P. A system of this type is disclosed in U. S. Patent 3,752,932.

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Loop Throttling Controls

In a loop communication system of the form suggested schematically in Fig. 1 station P may send unique flag (control) characters. These may be used to delimit data messages originating at P, and also to identify time slots which may be seized (and over-written) by individual secondary stations S for their return transmissions to P. A system of this type is disclosed in U. S. Patent 3,752,932.

The flag characters used for controlling secondary station transmissions may have two distinct forms; one form (termed "Idle" flag) is used to alert the secondary stations but inhibit transmissions therefrom, and the other form (termed "Go-Ahead" flag) is used to enable secondary transmissions. The Idle flags may be used to effect various specific "throttling" actions described below with cost-performance benefits.

One specific type of throttling action is useful to prevent overrun type interference between closely concatenated transmissions of successive stations S, due to handling restrictions at P. Assume for instance that P is organized to process indeterminate length strings of characters received from any one station S in pairs (e.g., for higher speed transmission to computing apparatus externally linked to P), and to insert a "filler" character after the last received character if the string has odd length.

In this case P could send a pattern of alternating Go-Ahead and Idle flag characters; thereby restricting the concatenated transmission to begin at an odd- character position after the end of transmission by a preceding station S; avoiding potential interference with the "filler" processing by P (without imposing additional buffer storage costs on P). This can be generalized to the case of receiving varied length character strings and processing them in n (greater than
2) character groups; by having P send a flag pattern of a Go-Ahead character followed by n-1 Idle characters.

Another applicat...