| 摘要 |
Trinary digital information is communicated over a pair of electrically conductive lines terminated line to line at at least one extremity by an impedance which generally matches the characteristic impedance of the two lines with respect to each other. One or more transmitters in electrical communication with the two lines selectively impose a first potential difference, a second potential difference distinct from the first, or no potential difference across the lines. One or more receivers in electrical communication with the two lines sense the first potential difference and interpret that as a first logical state, sense the second potential difference and interpret that as a second logical state, and sense no potential difference across the two lines and interpret that as a third logical state. In an embodiment the transmitters present no potential difference across the lines by presenting an impedance substantially higher than the characteristic impedance of the lines with respect to each other to the two lines. Preferably a plurality of nodes communicate in parallel with the two lines in bus fashion, some nodes capable of transmitting across the two lines as described above, and some nodes capable of sensing the discriminating the three logical states as described above, two of the states communicating binary information at discrete times and the other state marking the discrete times.
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