Browse Prior Art Database

Block Polling

IP.com Disclosure Number: IPCOM000120581D
Original Publication Date: 1991-May-01
Included in the Prior Art Database: 2005-Apr-02
Document File: 2 page(s) / 70K

Publishing Venue

IBM

Related People

Craddock, DF: AUTHOR [+3]

Abstract

Interactive communications systems must provide a method of delivering information in two directions. In the case of interactive computer communications, this usually entails communication between a master (host) and slave (workstation or terminal). There are two basic methods of delivering information from a slave device, polling and interrupting. In many cases, interrupting is not possible and polling must be used. Polling involves the master asking if the slave has anything to send, and the slave responding either yes or no. If many devices are to be polled by a single master, it can take a significant amount of time between polls on a given device. If this time is long, it increases the delay before a command (such as a keystroke) can be passed to the master.

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This is the abbreviated version, containing approximately 52% of the total text.

Block Polling

      Interactive communications systems must provide a method
of delivering information in two directions.  In the case of
interactive computer communications, this usually entails
communication between a master (host) and slave (workstation or
terminal).  There are two basic methods of delivering information
from a slave device, polling and interrupting. In many cases,
interrupting is not possible and polling must be used.  Polling
involves the master asking if the slave has anything to send, and the
slave responding either yes or no.  If many devices are to be polled
by a single master, it can take a significant amount of time between
polls on a given device.  If this time is long, it increases the
delay before a command (such as a keystroke) can be passed to the
master.

      The block polling procedure is an approach which can be used on
remote teleprocessing (TP) lines, when a remote link controller is
used, to reduce the time between polls and, therefore, increase the
speed with which user inputs (keystrokes, etc.) can be accepted.

      Block polling is a method where a single query is used to
interrogate all of the devices at the remote site in order to check
all of them for inputs.  The master device sends a message to the
communications controller at the remote site asking which devices
have data.  The communications controller, which has been polling the
attached slave devices independently, then responds with a list of
the devices which need attention, and possibly with data from those
devices.

      In order to effectively use block polling, the remot...