Method and apparatus for interfacing synchronous data devices over an asynchronous communications channel

Claim 2

In a communication system having first and second synchronous data terminals coupled via an asynchronous communications channel, the asynchronous communications channel having a channel baud rate, an interface circuit for interfacing between the asynchronous communications channel and the first synchronous data terminal, comprising: a transmit means for transmitting an outgoing asynchronous character data stream having a first data format to the asynchronous communications channel upon receipt of a first synchronous bit data stream from the first synchronous data terminal, said transmit means converting the first synchronous bit data stream to form the outgoing asynchronous character data stream; and a receive means for asynchronously receiving an incoming asynchronous character data stream from the asynchronous communications channel, wherein the incoming asynchronous character data stream has the first data format, said receive means converting the incoming asynchronous character data stream to form a second synchronous bit data stream and synchronously providing said second synchronous bit data stream to the first synchronous data terminal.

Claim 3

The communication system of claim 1 wherein the transmit means comprises: a synchronous receiver means for receiving the first synchronous bit data stream from the first synchronous data terminal, said synchronous receiver means converting the first synchronous bit data stream into the first data format and forming the outgoing asynchronous character data; an asynchronous transmitter means for asynchronously transmitting the outgoing asynchronous character data stream to the asynchronous communications channel; and a first control means coupled to the synchronous receiver means, and the asynchronous transmitter means for controlling the asynchronous transmission of the outgoing asynchronous character data stream.

Claim 4

The communication system of claim 2 wherein the first control means further comprises: a synchronous transmit clock means coupled to the synchronous receiver means to control the rate of clocking of the first synchronous bit data stream at a fixed rate relative to the baud rate of the asynchronous communications channel.

Claim 5

The communication system of claim 3 wherein the synchronous transmit clock means rate of clocking is set to 80% of the baud rate of the asynchronous communication channel.

Claim 6

The communication system of claim 1 wherein the receive means comprises: an asynchronous receiver means for receiving the incoming asynchronous character data stream over the asynchronous communications channel, said asynchronous receiver means converting the incoming asynchronous character data stream to form the second synchronous bit data stream; a receive data buffering means for temporarily holding the second synchronous bit data stream; a synchronous transmitter means for synchronously transmitting the second synchronous bit data stream held in the receive data buffering means to the first synchronous data terminal; and second control means coupled to the asynchronous receiver means, the receive data buffering means, and the synchronous transmitter means for controlling the synchronous transmission of the second synchronous bit data stream to the first synchronous data terminal.

Claim 7

The communication system of claim 5 wherein the receive data buffering means comprises a first-in, first-out queue in random access memory.

Claim 8

The communication system of claim 5 wherein the second control means further comprises: an adaptive clocking means coupled to the receive data buffering means and the synchronous transmitter means to vary adaptively the rate of clocking of the second synchronous bit data stream to the first synchronous data terminal.

Claim 9

The communication system of claim 9 wherein the adaptive clocking means rate of clocking varies between 70% and 90% of the baud rate of the asynchronous communications channel.

Claim 10

In a communication system having a first synchronous data terminal and a second synchronous data terminal coupled via an asynchronous communications channel, an interface circuit for interfacing between the first synchronous data terminal and the asynchronous communications channel, the interface circuit comprising: a transmit means which provides clocking for receiving synchronous data bits representing transmit data from the first synchronous data terminal, said transmit means transmitting the transmit data as asynchronous characters over the asynchronous communications channel; and a receive means for receiving asynchronous data characters representing receive data from the asynchronous communications channel, said receive means providing clocking for transmitting the receive data synchronously to the first synchronous data terminal.

Claim 11

In a communication system having a first synchronous data terminal and a second synchronous data terminal coupled via an asynchronous communications channel, an interface circuit for interfacing between the first synchronous data terminal and the asynchronous communications channel, the interface circuit comprising: a transmit means which provides clocking for receiving synchronous data bits representing transmit data from the first synchronous data terminal, said transmit means transmitting the transmit data as asynchronous characters over the asynchronous communications channel; and a receive means for receiving asynchronous data characters representing receive data from the asynchronous communications channel, said receive means providing clocking for transmitting the receive data synchronously to the first synchronous data terminal.

Claim 12

In a communication system having a first synchronous data terminal and a second synchronous data terminal coupled via an asynchronous communications channel, a method for interfacing synchronous bit data streams from the first synchronous data terminal over the asynchronous communications channel operating at a baud rate, the method comprising the steps of: providing the first synchronous data terminal with a synchronous transmit clock to clock a first synchronous bit data stream transmitted by said first synchronous data terminal; converting said synchronous bit data stream to an outgoing asynchronous character data stream; transmitting the outgoing asynchronous character data stream over the asynchronous communications channel at the baud rate of said asynchronous communications channel; receiving an incoming asynchronous character data stream over the asynchronous communications channel at the baud rate of said asynchronous communications channel; converting the received incoming asynchronous character data stream to a second synchronous bit data stream; and providing said first synchronous data terminal a synchronous receive clock to clock said second synchronous bit data stream to said first synchronous data terminal in a synchronous bit data stream format.

Claim 13

In a communication system having a first synchronous data terminal and a second synchronous data terminal coupled via an asynchronous communications channel, a method for interfacing synchronous bit data streams from the first synchronous data terminal over the asynchronous communications channel operating at a baud rate, the method comprising the steps of: providing the first synchronous data terminal with a synchronous transmit clock to clock a first synchronous bit data stream transmitted by said first synchronous data terminal; converting said synchronous bit data stream to an outgoing asynchronous character data stream; transmitting the outgoing asynchronous character data stream over the asynchronous communications channel at the baud rate of said asynchronous communications channel; receiving an incoming asynchronous character data stream over the asynchronous communications channel at the baud rate of said asynchronous communications channel; converting the received incoming asynchronous character data stream to a second synchronous bit data stream; and providing said first synchronous data terminal a synchronous receive clock to clock said second synchronous bit data stream to said first synchronous data terminal in a synchronous bit data stream format.