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Browse Prior Art Database

Varying Attention Interrupt Delay

IP.com Disclosure Number: IPCOM000086487D
Original Publication Date: 1976-Sep-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 2 page(s) / 54K

Publishing Venue

IBM

Related People

Chu, D: AUTHOR

Abstract

Buffered communications multiplexors usually incorporate a response attention time delay which delays interrupting the computer until some minimum period of time after a portion of a message from a terminal has been stored in a buffer. Fig. 1 shows such an arrangement comprising multiplexor 11, computer 13 and terminals 15, 17 and 19.

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Varying Attention Interrupt Delay

Buffered communications multiplexors usually incorporate a response attention time delay which delays interrupting the computer until some minimum period of time after a portion of a message from a terminal has been stored in a buffer. Fig. 1 shows such an arrangement comprising multiplexor 11, computer 13 and terminals 15, 17 and 19.

The purpose of the attention time delay is to minimize the number of computer interrupts. A long attention delay will result in fewer computer interrupts because longer message portions will be buffered before the computer is interrupted, but the long time delay also lengthens interactive inquiry response time. If the attention delay is short, the interactive inquiry response time is improved but the computer overhead is increased because it is interrupted more often.

Because of the trade-off between response time and computer overhead, it is difficult to select an attention delay time which is appropriate for a plurality of different terminal system applications, some of which may be remote batch oriented which can accept long response delays and others of which may be interactive which require short response delay.

Fig. 2 shows multiplexor attention delay control logic circuit including status register 21 which stores a delay status code that is changed as applications become active or inactive to change the attention delay time. A 1200-baud communication line and 512-byte buffers 23, 25, 27 are a...