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TIME DIVISION MULTIPLEXER WITH EACH FRAME CONSISTING OF A FIXED LENGTH BIT ORIENTED ADDRESS FIELD AND A VARIABLE LENGTH CHARACTER ORIENTED DATA FIELD

  • US 3,855,422 A
  • Filed: 07/05/1973
  • Issued: 12/17/1974
  • Est. Priority Date: 07/10/1972
  • Status: Expired due to Term
First Claim
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1. A multiplexing device for controlling the transmission of data characters between a central station and selectively chosen ones of a plurality of terminal stations wherein:

  • the data characters are multiplexed into frames containing not more than one character for each terminal station with each frame consisting of a frame identifying character, an address character identifying the terminal stations for which frame data characters are present in the frame and a variable number of data characters, said device including;

    a receiving and a transmitting shift register for each terminal, Means connecting each shift register to its associated terminal for data transfer, circuits for connecting all of said receiving shift registers into a serial train of shift registers, other circuits for connecting said transmitting shift registers into a second serial train of shift registers, a normally closed switch for each shift register to bypass said circuits around the associated register, a reception control unit to store the data in said address field as received from a central station, means in said reception control unit to open selected ones of said switches for said receiving shift registers in accordance with the data in a received address field, means in said reception control unit for thereafter passing received signals representing said variable length data field to said receiving shift registers having opened switches, means at each terminal to store signals representing a data character to be transmitted into its associated transmitting shift register and to open the corresponding switch for said shift register, and a transmission control unit activated by storage of a data character in one or more of said transmission shift registers to control transmission to said central unit of a frame of data including the characters stored in said transmitting shift registers having opened switches.

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