Interface circuit for communicating between two data highways
First Claim
1. An interface comprising two symmetrical ports connectable to data highways, each of said ports including data terminals, handshake terminals, at least one control terminal to which can be applied a special command signal indicative of whether a data byte on said data terminals is information or a command, and status control means responsive to command bytes accompanied by said special command signal received from a data highway at either port to establish different statuses of the interface, including statuses in which the data terminals of the ports are placed in communication for the flow of data therebetween;
- means responsive to a predetermined command byte on one of said data highways which addresses the interface at one of said ports for causing the interface to enter a particular status; and
means responsive to the existence of said particular status and a byte received from said one data highway at said one port for generating a modified byte as a command byte at the other port.
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Accused Products
Abstract
An interface circuit for use in a data transmission system is designed to be used not only between a highway and a device but also to link highways and can be commanded to enter a status in which commands sent to it on one highway are modified and sent out as commands on a second highway so that a controller device on the one highway can control devices not only on that highway but also on the second highway, with extension, if desired, to a third highway or beyond. To achieve this, the interface circuit has two ports each for connection to a respective one of two substantially identical highways, and status control means responsive to signals received at either port to establish different statuses of the interface. For inter-highway communication, the status control means is responsive to a command signal of particular form at either port to produce a modified command signal at the other port.
51 Citations
11 Claims
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1. An interface comprising two symmetrical ports connectable to data highways, each of said ports including data terminals, handshake terminals, at least one control terminal to which can be applied a special command signal indicative of whether a data byte on said data terminals is information or a command, and status control means responsive to command bytes accompanied by said special command signal received from a data highway at either port to establish different statuses of the interface, including statuses in which the data terminals of the ports are placed in communication for the flow of data therebetween;
- means responsive to a predetermined command byte on one of said data highways which addresses the interface at one of said ports for causing the interface to enter a particular status; and
means responsive to the existence of said particular status and a byte received from said one data highway at said one port for generating a modified byte as a command byte at the other port. - View Dependent Claims (2, 3, 4, 5, 6, 7)
- means responsive to a predetermined command byte on one of said data highways which addresses the interface at one of said ports for causing the interface to enter a particular status; and
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8. An interface comprising two symmetrical ports connectable to data highways, each of which includes data terminals, handshake terminals, at least one control terminal to which can be applied a special command signal indicative of whether a data byte on said data terminals is information or a command, and status control means responsive to command bytes accompanied by said special command signal received from a data highway at either port to establish different statuses of the interface, including statuses in which the data terminals of the ports are placed in communication for the flow of data therebetween;
- means responsive to a predetermined byte on one of said data highways which addresses the interface at one of said ports for causing the interface to enter a particular status; and
means responsive to the existence of said particular status and a byte received from said one data highway at said one port for applying the special command signal to the control terminal of the other port and a command byte to the data terminals of the other port. - View Dependent Claims (9, 10, 11)
- means responsive to a predetermined byte on one of said data highways which addresses the interface at one of said ports for causing the interface to enter a particular status; and
Specification