MULTIPLE TERMINAL COMPUTER CONTROL SYSTEM FOR GROUP POLLING

• US 3,668,649 A
• Filed: 06/26/1970
• Issued: 06/06/1972
• Est. Priority Date: 06/26/1970
• Status: Expired due to Term

• Current Assignee: Unisys Corporation
• Original Assignee: John H. Pedersen, Michael J. Bedford
• Inventors: Pedersen, John H., Bedford, Michael J.
• Primary Examiner(s): Henon, Paul J.
• Assistant Examiner(s): Chapnick, Melvin B.
• Application Number:
  US05/050,251
• Time in Patent Office: 711 Days
• Field of Search: 340/172.5,147,150,163 179/15AL
• US Class Current: 710/109
• CPC Class Codes: G06F 13/22 using successive scanning, e.g. polling G06F13/24 takes precedence
• CPC Class Codes: G06F 13/366 using a centralised polling arbiter
• CPC Class Codes: H04L 5/02 Channels characterised by the type of signal

Abstract

A control system for permitting each one of a plurality of transmit ready terminal computers to reply to a single polling command from a central processor. In an environment wherein a plurality of remote-terminal computers are concatenated to a single modem, a single polling command from the central processor will permit all of the transmit ready terminal computers to transmit data information to the central processing unit. Each terminal computer, being individually controlled through its program, will periodically contend for the communication channel. Logic circuitry is disclosed herein to permit any one of the terminal computers to seize the communication line and to prevent interruption by another terminal computer.

Claims

1. In a data communication system, a multiple terminal computer control system for group polling comprising:

a central processing unit operable to transmit a plurality of communication control signals including a poll command having a general machine address, a communication channel operatively connected at one end to said central processing unit, a modem electrically connected to said communication channel at the other end to receive the communication control signals from said central processing unit, said modem operative to transmit data information through said communication channel, a plurality of terminal computers electrically connected in concatenation with said modem and selectively operative to generate data information for data transmission through said communication channel, and logical gating means within each of said terminal computers responsive to said poll command having a general machine address to operatively and exclusively couple any one of said terminal computers having a particular address to said modem for data transmission.

2. In a data communication system, a multiple terminal computer control system for group polling according to claim 1 wherein said logical gating means sequentially couple each of said concatenated terminal computers ready for data transmission to said communication channel in response to said poll command.

3. In a data communication system, a multiple terminal computer control system for group polling according to claim 1 wherein said logical gating means operatively couple only one terminal computer to the communication channel in response to said poll command.

4. In a data communication system, a multiple terminal computer control system for group polling according to claim 3 wherein said logical gating means couple another of said terminal computers to said communication channel in response to a successive poll command from said central processing unit.

5. In a data communication system, a multiple terminal computer control system for group polling, said system comprising:

a central processing unit operable to transmit a plurality of communication control signals including a poll command having a general machine address;

a communication channel operatively connected at one end to said central processing unit;

a plurality of modems electrically connected to said communication channel at the other end to receive the communication control signals from said central processing unit, said modems operative to transmit data information through said communication channel;

a plurality of terminal computers electrically connected in concatenation with each of said modems, said terminal computers selectively operative to generate data information for data transmission through said communication channel; and

logical gating means within each of said terminal computers responsive to said poll command having a general machine address to operatively and exclusively couple any one of said terminal computers having a particular address to its modem and additionally including means to set a flag within said coupled terminal computer for denying said terminal computer the opportunity for coupling to its modem until the next poll command having a general machine address.