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Partial Demand Response Interlock

IP.com Disclosure Number: IPCOM000088501D
Original Publication Date: 1977-Jun-01
Included in the Prior Art Database: 2005-Mar-04
Document File: 2 page(s) / 31K

Publishing Venue

IBM

Related People

Jewett, RP: AUTHOR [+3]

Abstract

In data transfer interfaces which require interlocked demand and acknowledgment (response) signalling between controlling and controlled stations to synchronize data transfers, the usual signalling protocol takes the form suggested in Fig. 1. The response pulse is both initiated and terminated in response to the detection of respective initiation and termination states of a precedent demand pulse, which in turn is interlocked to respective initiation and termination of a precedent response, etc. In this mode of signalling the widths and spacings of the pulses (hence the maximum data rate) are dependent upon the transmission distances between the stations.

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Partial Demand Response Interlock

In data transfer interfaces which require interlocked demand and acknowledgment (response) signalling between controlling and controlled stations to synchronize data transfers, the usual signalling protocol takes the form suggested in Fig. 1. The response pulse is both initiated and terminated in response to the detection of respective initiation and termination states of a precedent demand pulse, which in turn is interlocked to respective initiation and termination of a precedent response, etc. In this mode of signalling the widths and spacings of the pulses (hence the maximum data rate) are dependent upon the transmission distances between the stations.

Part of this distance dependency can be eliminated, as shown in Fig. 2, by removing the requirement to interlock terminations of consecutive demand and response pulses. In this arrangement the initiation of each pulse represents the total acknowledgment of the precedent function, and only the following necessary and sufficient timing conditions need be satisfied: T(A) = inverse of average data transfer rate T(B) < T(A)

Where T(A) represents the time between consecutive demand pulse initiations and T(B) represents the time between consecutive demand and response initiations. The precise values of these timing parameters will be a function of the technology used to implement the station logic, the transmission distance between the stations and the medium of communication.

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