Multi-terminal computer system with dual communication channels
First Claim
1. A communication system for connecting a computer to a plurality of separated, remotely spaced terminals, comprising:
- a continuous segment of bi-directional communication channel connected to each of the terminals;
a primary transmitter having its output connected to a first end of the communication channel;
a secondary transmitter having its output connected to the second end of the communication channel output connections from the computer to each of the transmitters;
a detector for the primary transmitter signal connected to the end of the communication channel adjacent to the secondary transmitter; and
switch means controlled by the output of the primary transmitter signal detector for energizing the secondary transmitter when the detector fails to receive the primary transmitter signal, whereby, in the event of failure of the primary transmitter or interruption within the communication channel, the secondary transmitter will provide the computer output to those terminals unable to receive the primary transmitter signal.
2 Assignments
0 Petitions
Accused Products
Abstract
A communication system for linking a central computer to a plurality of remotely spaced terminals employs a single run of coaxial cable formed in a loop extending in the vicinity of each of the terminals with its two ends terminating adjacent the head-end computer. The output of the computer is provided to a normally operative primary channel transmitter connected to one end of the cable as well as to a normally inoperative, secondary channel transmitter connected to the other end of the cable. Each of the terminals includes receivers for both the primary and secondary channel. Primary channel signal detectors located at the head-end and at each of the terminals energize the secondary channel transmitter and/or the secondary channel receivers at their respective detectors when they fail to receive the primary channel carrier. Failure of the primary channel transmitter or a break in the cable thus causes energization of the secondary transmitter and the secondary channel receivers at those terminals affected by the malfunction. Terminal polling protocols, initiated by the computer, employ both the primary and secondary transmitters to determine the condition of each of the elements of the system.
57 Citations
16 Claims
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1. A communication system for connecting a computer to a plurality of separated, remotely spaced terminals, comprising:
- a continuous segment of bi-directional communication channel connected to each of the terminals;
a primary transmitter having its output connected to a first end of the communication channel;
a secondary transmitter having its output connected to the second end of the communication channel output connections from the computer to each of the transmitters;
a detector for the primary transmitter signal connected to the end of the communication channel adjacent to the secondary transmitter; and
switch means controlled by the output of the primary transmitter signal detector for energizing the secondary transmitter when the detector fails to receive the primary transmitter signal, whereby, in the event of failure of the primary transmitter or interruption within the communication channel, the secondary transmitter will provide the computer output to those terminals unable to receive the primary transmitter signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 12, 15)
- a continuous segment of bi-directional communication channel connected to each of the terminals;
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9. A communication system, comprising:
- a computer;
a plurality of terminals disposed at remote, spaced locations relative to the computer;
a continuous, elongated segment of a signal conductor running along a path extending in proximity to the computer and to each of the terminals;
signal conducting connections extending between the signal conductor and each of the terminals;
a primary transmitter connected to one end of the signal conductor and providing output to the signal conductor on a first band-width;
a secondary transmitter connected to the opposite end of the signal conductor and providing output to the signal conductor on a secondary band-width, which differs from the first band-width;
output connections from the computer to both the primary and secondary transmitters;
a primary transmitter signal sensor connected to the signal conductor adjacent to the end connected to the secondary transmitter;
a secondary transmitter control circuit connected to the output of the last said sensor and operative to energize the secondary transmitter when the sensor does not detect a primary transmitter signal; and
pairs of first and second band-width receivers associated with each terminal;
whereby signals from the computer are normally transmitted to the terminals employing the primary transmitter and in the event of failure of the primary transmitter or of interruption of the signal conductor the secondary transmitter is energized and provides output to the signal conductor. - View Dependent Claims (10, 11, 13, 14, 16)
- a computer;
Specification