Network access device
First Claim
1. A network access device adapted to be connected to a data trunk for transmitting and receiving messages from said data trunk and for interconnecting various computer devices to said data trunk, said network access device comprised of:
- a data set for receiving and transmitting data into and out of the network access device for connection to a data trunk,a trunk control unit connected to said data set for bi-directional communication into and out of said trunk and for transmitting at least first and second types of command messages and for receiving at least first and second types of response messages, a first type of command message being generated by said trunk control unit to indicate the status of said trunk control unit and a first type of response message being used by said trunk control unit to control the status of said trunk control unit,a trunk control interface connected to said trunk control unit and having means for connection with at least one additional trunk control unit for buffering of data transmitted to and received from said trunk control unit, said trunk control interface being responsive to control signals to respond to said trunk control unit in a selected function from a group of available functions, said available functions including receiving data from or transmitting data into said data trunk,a network access device internal bus connected to said trunk control interface,a network access device processor operating as a microcode sequencer and issuing output control signals connected with said internal bus for controlling said trunk control interface and trunk control unit by generating addressed status and interrupt control signals to said trunk control interface and to said trunk control unit, said processor generating at least some of said addressed control signals in response to signals received from said trunk control interface and said trunk control unit, said processor also generating a second type of command message and receiving a second type of response message to control the network access device,a trunk control unit input bus connected to said trunk control unit and said data set to receive signals from said data set and which is accessed by a number of tri-state drivers included in said trunk control unit each of which is controlled by said microcode sequencer logic and clock signals produced by said network access device processor and transferred by said trunk control interface to control access to said trunk control unit input bus at predetermined times according to said microcode sequence,an internal network access device memory connected with said internal bus, anda device interface connected with said internal bus for communication through said trunk control interface to said trunk control unit and to said data trunk through said data set and having an output device channel adapted for connection to an appropriate computer device.
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Accused Products
Abstract
A network access device (NAD) is comprised of a data set for coupling to a data communication trunk, a trunk control unit (TCU) connected with the data set, a trunk control interface (TCI) connecting the TCU to an internal data bus, an internal memory, a microprocessor control and a device interface for connection to a computer or some computer peripheral device. The data set provides for two-way communication from the data trunk to the TCU. Various network access devices connected to the data trunk communicate with one another. Every normal communication between NADs includes a concurrent, predictable state change in both NADs. The response to a message from one NAD to another includes information concerning what occurred upon receipt of the message. Various latches, sequencers, microprocessor logic and registers provide for functions according to various input and output states of response.
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Citations
18 Claims
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1. A network access device adapted to be connected to a data trunk for transmitting and receiving messages from said data trunk and for interconnecting various computer devices to said data trunk, said network access device comprised of:
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a data set for receiving and transmitting data into and out of the network access device for connection to a data trunk, a trunk control unit connected to said data set for bi-directional communication into and out of said trunk and for transmitting at least first and second types of command messages and for receiving at least first and second types of response messages, a first type of command message being generated by said trunk control unit to indicate the status of said trunk control unit and a first type of response message being used by said trunk control unit to control the status of said trunk control unit, a trunk control interface connected to said trunk control unit and having means for connection with at least one additional trunk control unit for buffering of data transmitted to and received from said trunk control unit, said trunk control interface being responsive to control signals to respond to said trunk control unit in a selected function from a group of available functions, said available functions including receiving data from or transmitting data into said data trunk, a network access device internal bus connected to said trunk control interface, a network access device processor operating as a microcode sequencer and issuing output control signals connected with said internal bus for controlling said trunk control interface and trunk control unit by generating addressed status and interrupt control signals to said trunk control interface and to said trunk control unit, said processor generating at least some of said addressed control signals in response to signals received from said trunk control interface and said trunk control unit, said processor also generating a second type of command message and receiving a second type of response message to control the network access device, a trunk control unit input bus connected to said trunk control unit and said data set to receive signals from said data set and which is accessed by a number of tri-state drivers included in said trunk control unit each of which is controlled by said microcode sequencer logic and clock signals produced by said network access device processor and transferred by said trunk control interface to control access to said trunk control unit input bus at predetermined times according to said microcode sequence, an internal network access device memory connected with said internal bus, and a device interface connected with said internal bus for communication through said trunk control interface to said trunk control unit and to said data trunk through said data set and having an output device channel adapted for connection to an appropriate computer device. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A network access device comprised of:
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a data set adapted to be connected to a data trunk, trunk control unit means connected to said data set for bi-directional communication into and out of said trunk and for transmitting first and second types of command messages and for receiving response messages, and wherein for each command message sent as the response to a received message, the command message provides status information about the network access device, wherein said trunk control unit is comprised of; an instruction address holding register for holding each instruction address in a received message from said data set during execution by said network access device so that it is not lost, an error detection logic means connected to said instruction address holding register for detecting an error status in the trunk control unit, and means connected to said error detection logic means for sending a first type of command message to said data set indicating an error status in response to a signal from said error detection logic means, said first type of command message containing a portion which consists of the instruction address received from said instruction address holding register which resulted in the error status, a trunk control interface connected to said trunk control unit for buffering of data, said trunk control interface having means for connection to at least one additional trunk control unit, and wherein said trunk control interface includes a control latch for receiving status information from said trunk control unit with respect to the mode of operation of said trunk control unit, a network access device internal bus connected to said trunk control interface, a network access device microprocessor connected with said internal bus for controlling said trunk control interface and trunk control unit by generating addressed control signals to said trunk control interface and said time control unit, an internal network access device memory connected with said internal bus, and a device interface connected with said internal bus for communication through said trunk control interface to said trunk control unit and to said data network through said data set and having an output device channel adapted for connection to an appropriate computer device. - View Dependent Claims (17, 18)
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Specification