TO COMPUTER

United States Patent ti9j

Boenke et al.

[in 3,836,888 [45] Sept. 17, 1974

[54] VARIABLE MESSAGE LENGTH DATA

ACQUISITION AND RETRIEVAL SYSTEM
AND METHOD USING TWO-WAY COAXIAL
CABLE

[76] Inventors: Clyde O. Boenke, 1409 Orborview Blvd.; Murray H. Miller, 1534 Glastonbury, both of Ann Arbor, Mich. 48103; Michael R. Levine, 3605 Fredrick; Victor H. Rigotte, B595 Greenbrier Blvd., both of Ann Arbor, Mich. 48105; Weston E. Vivian, 2717 Kerutworth Dr.; William C. Hall, 10 Ridgeway, both of Ann Arbor, Mich. 48104

[22] Filed: May 22, 1972

[21] Appl. No.: 255,477

[52] U.S.CI 340/172.5, 178/D1G. 13,

178/DIG. 22, 178/5.6,178/66 R

[51] Int. CI G06f 3/04, H04j 9/00, H04n 7/14

[58] Field of Search 178/66 R, 58, 5.6, 79,

178/113, 17; 179/15 BA, 15 BV, 15 FD, 2 DP, 84 VF; 343/175; 340/176, 172.5, 166 R, 173 SP, 174 SP, 172 S, 36 SR

[56] References Cited

UNITED STATES PATENTS

3,003,143 10/1961 Beurrier 340/347

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3,310,778 3/1967 Grundfest et al 340/166

3,500,327 3/1970 Belcher et al 340/154

3,526,892 9/1970 Bartlett et al 340/365

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3,560,936 2/1971 Busch 340/172.5

3,564,509 2/1971 Perkins et al 340/172.5

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3,675,513 7/1972 Flanagan et al 179/84 VF

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3,701,851 10/1972 Starrett 179/15 BY

OTHER PUBLICATIONS

R. K. Jurgen, "Two Way Applications for Cable Tele

A control computer is connected via a coaxial cable to a plurality of remote terminals. Data and command signals are transmitted in the forward direction from the computer to the terminals by time-multiplexing the signals on one channel of the cable and data and request signals are transmitted in the return direction from the terminal to the computer by timemultiplexing these signals on a different channel of the cable. Each terminal is equipped with several inputoutput devices which operate at different speeds. The computer operates at high speed to fill its main memory with commands. An interface is connected between the computer and the cable and is capable of operating at different speeds, i.e., at different time intervals between transmissions of digital words to different terminals or between repeated transmissions to the same terminal. It normally operates at a speed lower than the speed of the computer to service the low speed terminal devices. However, when a command for a high speed operation at a terminal is recognized, the interface enters a burst mode which supplies commands to the terminal at the high speed of the computer. Transmission in the forward direction is accomplished by frequency shift keying, and in the return direction by phase shift modulation. Words are transmitted serial-by-bit. Each terminal has a unique means for storing its permanent terminal address parallel-by-bit for comparison with serial address bits transmitted by the computer. The terminals are divided into several different major groups. The computer addresses the terminals by first transmitting a major address to select the proper group, and then sends a minor address to select the terminal within the major group. Each terminal is provided with a local storage and a novel keyboard for entering request codes into the storage. Each terminal is also provided with a visual display means for displaying data transmitted from the computer. A novel one-line display also provides the terminal with a visual display of the information entered on the keyboard or a message sent to the terminal.