摘要:
Asynchronous, collision-free communication of data packets is provided on a local shared bus network interconnecting a plurality of N ordered transceiving ports (1,2,3....,J,...N). The bus network includes a data bus (20) having a propagation delay time T and a control line (26) having a propagation delay from port J to port N of R(J), each port J including means (40) for ascertaining the presence of a data packet on said data bus at said port J, and being adapted to send and receive on said data bus variable length data packets. Each port J upon having a packet available for transmission executes the steps of placing a signal S(J) on said control line (26) to communicate to ports J + 1, J +2,...,N an intention to transmit a packet, delaying transmission for the time interval R(J) + T, ascertaining that no signal indicating an intention to transmit is being received at port J from any of ports 1,2,...,J- 1 , and that said data bus (20) at port J is unoccupied, transmitting the packet and terminating signal S(J). Prior to placing the signal S(J) on the control line (26), the port J ascertains that the data bus (20) is unoccupied for a time period 2T.
摘要:
Asynchronous, collision-free communication of data packets is provided on a local shared bus network interconnecting a plurality of N ordered transceiving ports (1,2,3....,J,...N). The bus network includes a data bus (20) having a propagation delay time T and a control line (26) having a propagation delay from port J to port N of R(J), each port J including means (40) for ascertaining the presence of a data packet on said data bus at said port J, and being adapted to send and receive on said data bus variable length data packets. Each port J upon having a packet available for transmission executes the steps of placing a signal S(J) on said control line (26) to communicate to ports J + 1, J +2,...,N an intention to transmit a packet, delaying transmission for the time interval R(J) + T, ascertaining that no signal indicating an intention to transmit is being received at port J from any of ports 1,2,...,J- 1 , and that said data bus (20) at port J is unoccupied, transmitting the packet and terminating signal S(J). Prior to placing the signal S(J) on the control line (26), the port J ascertains that the data bus (20) is unoccupied for a time period 2T.
摘要:
Apparatus for printing data on a document includes two printing devices. The first printing device 42 prints the data in human readable form on a document. The second printing device 52 also prints the data on the document in a form which can be read by an optical reading system. The first printing device operates in response to data signals supplied to the apparatus, from a keyboard 32 or otherwise, to print on one portion of the document. Simultaneously coded representations of the data being printed are produced and stored. The second printing device operates in response to the coded representation of the data and prints further representations of the data on another portion of the document. These representations can be read using an optical reading system. The coded representations can include additional code providing for error correction.
摘要:
Apparatus for printing data on a document includes two printing devices. The first printing device 42 prints the data in human readable form on a document. The second printing device 52 also prints the data on the document in a form which can be read by an optical reading system. The first printing device operates in response to data signals supplied to the apparatus, from a keyboard 32 or otherwise, to print on one portion of the document. Simultaneously coded representations of the data being printed are produced and stored. The second printing device operates in response to the coded representation of the data and prints further representations of the data on another portion of the document. These representations can be read using an optical reading system. The coded representations can include additional code providing for error correction.