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United States Patent4555781
Baldry , ; et al.November 26, 1985
Title
Conversational video system having local network control
Abstract
A video conversational data communication network (30) in which subscribers (34, 36) may conduct conversational video textual data communications with one or more keystations (70, 602, 98) in the network (30). Each keystation (70, 602, 98) is associated with a keystation terminal controller interface (68, 96, 600) which is in turn connected to a switching concentrator computer (46, 48, 110, 112, 114) and a message switching node (32, 42, 44) for routing calls throughout the network (30). The concentrators (46, 48, 110, 112, 114) enable calls to be directly routed to controllers (68, 96, 600) sharing the same node (32, 42, 44) without having to go through the node (32, 42, 44). The controller (68, 96, 600) locally stores (304, 306) video conversational textual data for its associated keystations (70, 82, 84, 98, 100, 602) and enables two different designated keystations to conduct two different video conversations with a common keystation in a split screen display (76). The split screen display (76) may also be used to display retrievable data from a data base (50, 52) for simultaneous display (76) along with a video conversation. The data is transmitted between connected controllers (96, 602) in packets which contain less than the total displayable data content of the video message input via the keyboard (72). The controller (96, 602) also enables preparation of responses prior to transmission to the other party and while receiving a transmission from that party. Prior to completion of a call, the controller (96, 602) provides an incoming calls queue video display (76) at the connected keystations (96, 602).
Inventors:Baldry; Kenneth (Isleworth, GB2), Davids; Martin  (Leigh-on-Sea, GB2)
Assignee:Reuters Ltd. (London, GB2)
Appl. No.:480211
Filed:March 30, 1983
Current U.S. Class:370/260 715/733 715/751 345/2.2 
Field of Search:370/60,58,62,61 340/721,717
U.S. Patent Documents
3166636January 1965Rutland et al.
4213124July 1980Barda et al.
4290062September 1981Marti et al.
4512011April 1985Turner
Other References
1981 International Conference on Communications, Denver, Colo., USA; Jun. 14-18, 1981; "The International Packet Switching Services", in France; pp. 50.2.1-50.2.5..~
Primary Examiner: Olms; Douglas W.
Attorney, Agent or Firm:Stiefel, Gross, Kurland & Pavane
Claims

What is claimed is:
1. In a video communication network capable of providing textual data messages to a plurality of subscriber terminals throughout said network, at least a portion of said plurality of subscriber terminals comprising subscriber keystations, each of said subscriber keystations comprising a keyboard means for operator input of textual data messages and associated data control signals to said network via said keyboard means and a video display means for providing a textual video display of at least keyboard generated data input to said network; the improvement comprising at least one message switching interface means for routing video conversational textual data message calls throughout said network, said data messages being transmitted through said network in a plurality of data packets, a plurality of said keystations being operatively connected to said one message switching interface means, said one message switching interface means comprising message routing logic means and storage means operatively connected to said message routing logic means for providing message routing logic control signals and further comprising display control logic means and local video display storage means for locally storing video conversational textual data for providing a video display thereof to at least a pair of said keystations which are operatively connected together through said one interface means in a completed call in said network, said keyboard means comprising means for providing unique calling signals to said interface means for initiating calls to a designated keystation portion of said plurality of keystations in said network, said one interface means further comprising means for receiving said calling signals provided thereto for completing a call to said designated connected keystation, said message routing logic means comprising means for controlling the routing of said calling signals and said data packets to said designated keystations to control the completion and conducting of said initiated calls, said display control logic means comprising means for providing on said pair of connected keystation video display means a video display of video conversational textual data transmitted in said data packets between said connected keystations in said network with which said call has been completed via said separate keyboard means associated with said pair of connected keystations, said keyboard means calling signal providing means further comprising means for providing said data packets to said interface means for providing said video conversational textual data messages between said connected keystations during a call therebetween, said one message switching interface means storage means comprising means for retrievably storing a packet routing control program for controlling the routing of said data packets between said connected keystations during said call therebetween, said switching interface means message routing logic means comprising means capable of accessing said packet routing control program in response to said calling signals and said data packet provision for connecting and routing said provided data packets between said connected keystations, said one message switching interface means comprising at least one node computer message routing means, at least one pair of switching concentrator computer message routing means operatively connected to said one node computer message routing means and to each other via a message communications link and at least one keystation terminal controller interface means operatively connected between each of said keystations between which said call is completed and each of said pair of switching concentrator computer message routing means, said node computer message routing means comprising said message routing logic means and said storage means operatively connected thereto, each of said switching concentrator computer message routing means comprising a local message routing logic means and a local storage means operatively connected thereto, each of said local storage means comprising means for locally retrievably storing a copy of said packet routing control program, each of said local message routing logic means comprising means capable of accessing said locally retrievably stored packet routing control program in response to said calling signals and said data packet provision between said keystations connected to said switching concentrator computer message routing means for enabling direct routing of calls between said keystations connected to said switching concentrator computer message routing means.

2. A video conversational communication network in accordance with claim 1 wherein said one pair of switching concentrator computer message routing means are directly connected to each other via said message communications link for enabling said direct routing of said data packets between said keystations connected thereto without routing said data packets through said one node computer message routing means, whereby said data packets may be transmitted between said connected keystations without having to transit said node.

3. A video conversational communication network in accordance with claim 2 wherein said one message switching interface means further comprises at least another of said node computer message routing means, one of said one pair of switching concentrator computer message routing means being directly connected to said one node computer message routing means and the other of said one pair of switching concentrator computer message routing means being directly connected to said other of said node computer message routing means, with said one pair of switching concentrator computer message routing means further being directly connected to each other via said message communications link.

4. A video conversational communication network in accordance with claim 3 wherein said one and said other of said node computer message routing means are further directly connected to each other via said message communications link.

5. A video conversational communication network in accordance with claim 2 wherein said one message switching interface means further comprises a third one of said switching concentrator computer message routing means directly connected to said one pair of said switching concentrator computer message routing means via said message communications link for directly routing calls between said one pair of said switching concentrator computer message routing means and said third one of said switching concentrator computer message routing means, another of said keystation terminal controller interface means being operatively connected between another keystation in said plurality of keystations and said third one of said switching concentrator computer message routing means.

6. A video conversational communication network in accordance with claim 5 wherein said one pair and said third one of said switching concentrator computer message routing means are connected together via said message communications link in a daisy chain configuration with said one node computer message routing means.

7. A video conversational communication network in accordance with claim 5 wherein said third one of said switching concentrator computer message routing means is directly connected to each one of said one pair of switching concentrator computer message routing means via said message communications link.

8. A video conversational communication network in accordance with claim 5 wherein each one of said one pair of said switching concentrator computer message routing means are directly connected to said one node computer message routing means.

9. A video conversational communication network in accordance with claim 8 wherein said third one of said switching concentrator computer message routing means is only connected via said message communications link to said one node computer message routing means via said connections through said one pair of said switching concentrator computer message routing means.

10. A video conversational communication network in accordance with claim 7 wherein said third one of said switching concentrator computer message routing means is only connected via said message communications link to said one node computer message routing means via said connections through said one pair of said switching concentrator computer message routing means.

11. A video conversational communication network in accordance with claim 1 wherein each one of said one pair of said switching concentrator computer message routing means are directly connected to said one node computer message routing means.

12. A video conversational communication network in accordance with claim 1 wherein said one message switching interface means further comprises at least another of said node computer message routing means, each of said one pair of said switching concentrator computer message routing means being directly connected to each of said node computer message routing means via said message communications link.

13. A video conversational communication network in accordance with claim 12 wherein said one and said other of said node computer message routing means are further directly connected to each other via said message communications link.

14. A video conversational communication network in accordance with claim 1 wherein said display control logic means comprises means for initiating transmission of said keyboard generated video conversational textual data packets between said connected keystations in multicharacter data packets comprising less than the total video displayable data content of one video displayable line of one of said video textual data conversational messages.

15. A video conversational communication network in accordance with claim 2 wherein said display control logic means comprises means for initiating transmission of said keyboard generated video conversational textual data packets between said connected keystations in multicharacter data packets comprising less than the total video displayable data content of one video displayable line of one of said video textual data conversational messages.

16. A video conversational communication network in accordance with claim 6 wherein said display control logic means comprises means for initiating transmission of said keyboard generated video conversational textual data packets between said connected keystations in multicharacter data packets comprising less than the total video displayable data content of one video displayable line of one of said video textual data conversational messages.

17. A video conversational communication network in accordance with claim 8 wherein said display control logic means comprises means for initiating transmission of said keyboard generated video conversational textual data packets between said connected keystations in multicharacter data packets comprising less than the total video displayable data content of one video displayable line of one of said video textual data conversational messages.

18. A video conversational communication network in accordance with claim 9 wherein said display control logic means comprises means for initiating transmission of said keyboard generated video conversational textual data packets between said connected keystations in multicharacter data packets comprising less than the total video displayable data content of one video displayable line of one of said video textual data conversational messages.

19. A video conversational communication network in accordance with claim 13 wherein said display control logic means comprises means for initiating transmission of said keyboard generated video conversational textual data packets between said connected keystations in multicharacter data packets comprising less than the total video displayable data content of one video displayable line of one of said video textual data conversational messages.

20. A video conversational communication network in accordance with claim 1 wherein said display control logic means comprises means for providing on said one connected keystation video display means a substantially simultaneous video display of video conversational textual data received from two different designated keystations in said network connected to different ones of said switching concentrator computer message routing means through which calls are completed via said separate keyboard means associated with said two different designated keystations and transmitted to said two different designated keystations via said keyboard means associated with said one connected keystation, whereby different video conversations may be substantially simultaneously carried out with different keystations on a common video display.

21. A video conversational communication network in accordance with claim 2 wherein said display control logic means comprises means for providing on said one connected keystation video display means a substantially simultaneous video display of video conversational textual data received from two different designated keystations in said network connected to different ones of said switching concentrator computer message routing means through which calls are completed via said separate keyboard means associated with said two different designated keystations and transmitted to said two different designated keystations via said keyboard means associated with said one connected keystation, whereby different video conversations may be substantially simultaneously carried out with different keystations on a common video display.

22. A video conversational communication network in accordance with claim 6 wherein said display control logic means comprises means for providing on said one connected keystation video display means a substantially simultaneous video display of video conversational textual data received from two different designated keystations in said network connected to different ones of said switching concentrator computer message routing means through which calls are completed via said separate keyboard means associated with said two different designated keystations and transmitted to said two different designated keystations via said keyboard means associated with said one connected keystation, whereby different video conversations may be substantially simultaneously carried out with different keystations on a common video display.

23. A video conversational communication network in accordance with claim 8 wherein said display control logic means comprises means for providing on said one connected keystation video display means a substantially simultaneous video display of video conversational textual data received from two different designated keystations in said network connected to different ones of said switching concentrator computer message routing means through which calls are completed via said separate keyboard means associated with said two different designated keystations and transmitted to said two different designated keystations via said keyboard means associated with said one connected keystation, whereby different video conversations may be substantially simultaneously carried out with different keystations on a common video display.

24. A video conversational communication network in accordance with claim 9 wherein said display control logic means comprises means for providing on said one connected keystation video display means a substantially simultaneous video display of video conversational textual data received from two different designated keystations in said network connected to different ones of said switching concentrator computer message routing means through which calls are completed via said separate keyboard means associated with said two different designated keystations and transmitted to said two different designated keystations via said keyboard means associated with said one connected keystation, whereby different video conversations may be substantially simultaneously carried out with different keystations on a common video display.

25. A video conversational communication network in accordance with claim 13 wherein said display control logic means comprises means for providing on said one connected keystation video display means a substantially simultaneous video display of video conversational textual data received from two different designated keystations in said network connected to different ones of said switching concentrator computer message routing means through which calls are completed via said separate keyboard means associated with said two different designated keystations and transmitted to said two different designated keystations via said keyboard means associated with said one connected keystation, whereby different video conversations may be substantially simultaneously carried out with different keystations on a common video display.

26. A video conversational communication network in accordance with claim 1 wherein said one message switching interface means further comprises at least one host computer network control means with said one node computer message routing means being operatively connected thereto, said host computer network control means comprising remote message routing logic means and remote storage means operatively connected thereto, said remote storage means comprising means for remotely retrievably storing a copy of said packet routing control program, said remote message routing logic means comprising means capable of accessing said remotely retrievably stored packet routing control program in response to said unique calling signals provided thereto for completing said call to said designated connected keystation, said data packets being transmitted between said connected keystation after said call has been completed therebetween without intervention of said one host computer network control means.

27. A video conversational communication network in accordance with claim 26 wherein said one pair of switching concentrator computer message routing means are directly connected to each other via said message communications link for enabling said direct routing of said data packets between said keystations connected thereto without routing said data packets through said one node computer message routing means, whereby said data packets may be transmitted between said connected keystations without having to transit said node.

28. A video conversational communication network in accordance with claim 27 wherein said message routing logic means selects the shortest route for said data packets in accordance with said retrievably stored packet routing control program.

29. A video conversational communication network in accordance with claim 27 wherein said one message switching interface means further comprises at least another of said node computer message routing means, one of said one pair of switching concentrator computer message routing means being directly connected to said one node computer message routing means and the other of said one pair of switching concentrator computer message routing means being directly connected to said other of said node computer message routing means, with said one pair of switching concentrator computer message routing means further being directly connected to each other via said message communications link, said other of said node computer message routing means being operatively connected to said one host computer network control means.

30. A video conversational communication network in accordance with claim 29 wherein said one and said other of said node computer message routing means are further directly connected to each other via said message communications link.

31. A video conversational communication network in accordance with claim 27 wherein said one message switching interface means further comprises a third one of said switching concentrator computer message routing means directly connected to said one pair of said switching concentrator computer message routing means via said message communications link for directly routing calls between said one pair of said switching concentrator computer message routing means and said third one of said switching concentrator computer message routing means, another of said keystation terminal controller interface means being operatively connected between another keystation in said plurality of keystations and said third one of said switching concentrator computer message routing means.

32. A video conversational communication network in accordance with claim 31 wherein said one pair and said third one of said switching concentrator computer message routing means are connected together via said message communications link in a daisy chain configuration with said one node computer message routine means.

33. A video conversational communication network in accordance with claim 31 wherein said third one of said switching concentrator computer message routing means is directly connected to each one of said one pair of switching concentrator computer message routing means via said message communications link.

34. A video conversational communication network in accordance with claim 31 wherein each one of said one pair of said switching concentrator computer message routine means are directly connected to said one node computer message routing means.

35. A video conversational communication network in accordance with claim 34 wherein said third one of said switching concentrator computer message routing means is only connected via said message communications link to said one node computer message routing means via said connections through said one pair of said switching concentrator computer message routing means.

36. A video conversational communication network in accordance with claim 33 wherein said third one of said switching concentrator computer message routing means is only connected via said message communications link to said one node computer message routing means via said connections through said one pair of said switching concentrator computer message routing means.

37. A video conversational communication network in accordance with claim 26 wherein each one of said one pair of said switching concentrator computer message routing means are directly connected to said one node computer message routing means.

38. A video conversational communication network in accordance with claim 26 wherein said one message switching interface means further comprises at least another of said node computer message routing means, each of said one pair of said switching concentrator computer message routing means being directly connected to each of said node computer message routing means via said message communication link, said other of said node computer message routing means being operatively connected to said one host computer network control means.

39. A video conversational communication network in accordance with claim 38 wherein said one and said other of said node computer message routing means are further directly connected to each other via said message communications link.

40. A video conversational communication network in accordance with claim 26 wherein said display control logic means comprises means for initiating transmission of said keyboard generated video conversational textual data packets between said connected keystations in multicharacter data packets comprising less than the total video displayable data content of one video displayable line of one of said video textual data conversational messages.

41. A video conversational communication network in accordance with claim 26 wherein said display control logic means comprises means for providing on said one connected keystation video display means a substantially simultaneous video display of video conversational textual data received from two different designated keystations in said network connected to different ones of said switching concentrator computer message routing means through which calls are completed via said separate keyboard means associated with said two different designated keystations and transmitted to said two different designated keystations via said keyboard means associated with said one connected keystation, whereby different video conversations may be substantially simultaneously carried out with different keystations on a common video display.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS

This application is related to the following commonly owned copending United States patent applications, the contents of which are all specifically incorporated by reference herein in their entirety: copending U.S. patent application Ser. No.
230,341, filed Jan. 30, 1981, now U.S. Pat. No. 4,388,489 and entitled "Conversational Video System", naming Jack Wigan, John Richards and David Ure as joint inventors thereof; and the contemporaneously filed copending U.S. patent application Ser. No. 480,331, entitled "Conversational Video System Having Contact Selection Control", which is a continuation-in-part of said U.S. patent application Ser. No. 230,341 and names the same inventors as in said patent application as joint inventors thereof, and is an improvement thereon, and is related to U.S. patent application Ser. No. 480,301, entitled "Improved Conversational Video System", naming Martin Davids, Peter Blackman and Lilly Teo as joint inventors thereof.

TECHNICAL FIELD

The present invention relates to two-way video communication systems and particularly to such systems capable of providing subscriber to subscriber video data communication in a conversational mode.

BACKGROUND ART

Communication systems for transmitting data point to point are well known, such as conventional telex systems and data base access systems. In addition, of course, telephone systems are well known two-way conversational communication media with the disadvantage being that a telephone system does not provide any hard copy nor does it allow you to, on the same device, obtain supplementary data while carrying on the conversation. Such supplementary data may be particularly important if the purpose of the conversation is commodity dealing such as in the money market. With respect to the telex communication, apart from its associated rate of speed, it does not enable you to readily carry on two different two-way telex communications alternatively so that you can carry on "telex conversations" with two different subscribers at substantially the same time. Moreover, neither the telex communication systems nor telephone communication systems provide a listing of incoming callers prior to acceptance of the message by the recipient. With respect to two-way data-base access systems, such prior art systems do not in reality provide a real time conversational communication in that they merely provide for remote storage of information which may subsequently be retrieved upon request by a subscriber or, in certain instances, can be provided to the subscriber if he is accessing the particular storage location to which the data is being provided. However, this is still not a real-time conversational type of video communication system in which a pair of subscribers or users can interact in real time in a conversational mode. With respect to prior art telephone and data-base access systems, a prior art system merging these two technologies is known as the Delphi system which is a telephone message management system in which speech messages may be pre-recorded and stored in a data base for subsequent automatic transmission to incoming callers and in which incoming messages may be stored for subsequent later transmission to prescribed recipients. However, this system is not a true conversational video communication system nor does it enable a particular user to carry on multiple conversations substantially simultaneously. Thus, there are no satisfactory prior art systems known to applicants which are capable of providing interactive conversational type of video data communications between pairs of users or subscribers nor such systems which enable multiple conversations to be carried out by a given user or subscriber in real-time and in association with data-base retrieval of supplementary data. These disadvantages of the prior art are overcome by the systems disclosed in the aforementioned copending United States patent applications. However, in the systems disclosed therein all calls which are routed between concentrators to carry out a conversation must be routed through a node, which limits the flexibility of the communication network and, in the instance where the node must be contacted via transatlantic cable or other long distance communication link, the possibility of lost or interrupted transmissions is increased. This problem is particularly acute where the two concentrator computers or concentrators are in the same local network but must, nevertheless, route the conversation through the mode. In the system of the present invention these disadvantages have been overcome.

DISCLOSURE OF THE INVENTION

A video conversational data communication network in which subscribers may conduct conversational video textual data communications with one or more keystations in the network. Each keystation is associated with a keystation terminal controller interface which is in turn connected to a message switching node for routing calls throughout the network, although, as will be described herein, calls between switching concentrators on the same local network are switched or routed directly between the switching concentrators without going through the node. The keystation controller interface locally stores video conversational textual data for its associated keystations and enables two different designated keystations to conduct two different video conversations with a common keystation in a split screen display. The split screen display may also be used to display retrievable data from a data base for simultaneous display along with a video conversation. The video conversational textual data is transmitted between connected keystation controller interfaces in packets which contain less than the total displayable data content of the conversational video textual data message input via the keyboard. The keystation controller interface also enables preparation of responses prior to transmission to the other party and while receiving a transmission from that party. Prior to completion of a call, the keystation controller interface provides an incoming calls queue video display at the connected keystations. This video display may contain a unique identifier for each keystation initiating a call as well as an interest message. The receiving keystation may then randomly select any of the displayed incoming calls irrespective of position in the queue and the video conversation may then take place using the associated keyboards and video displays. A hard copy print out of the video conversation may then be obtained on a printer. Each subscriber in the network may dynamically list in advance those subscribers from whom he is not prepared to accept calls via a facility termed CALL INHIBIT in which instance the network will not establish a converstion with an inhibited subscriber while permitting a conversation to be established with a subscriber who is not contained in the stored INHIBIT LIST. In addition, through a facility termed CALL LIST, a subscriber may dynamically specify in advance, either through a stored CALL LIST, or via a command message, that the network is to establish a conversation either with the first free subscriber or the first two free subscribers (DUAL CALL LIST) in the CALL LIST, or with the first free subscriber in the CALL LIST while selectively skipping contact with predesignated ones of possible free subscribers for a given call, so that with one call the network has a plurality of chances of establishing a desired conversation with one or more of a plurality of preselected subscribers in a variable contact pattern preselected by the originating subscriber. This CALL LIST facility can also be used by the originating subscriber to simultaneously send a preestablished page to various subscribers in the CALL LIST, any of which may then select it for display. Thus, the CALL LIST and CALL INHIBIT facilities enhance the use time of the terminals in a dynamic conversational environment. Copies of the CALL LIST and INHIBIT LIST records are kept at the keystation terminal controller interfaces to enable these functions to be performed, where applicable, without the necessity of access to the host computer. In addition, through the use of a DEAL KEY at the sending keystation keyboard a dialogue confirmation and acknowledgement is rapidly received without requiring a loss of control of the conversation by the sender. The concentrators are all preferably switching concentrators which provide local network control so as to switch or route conversational messages between callers sharing the same node directly between the switching concentrators without the necessity of having to go through the common node. In addition, whereas in the prior systems the concentrators could only be attached to the node that supported them and thus two lines were needed between each concentrator and node for reliability, the local network switching concentrators may be connected to each other as well as to the common node and obtain reliability with only a single line, since if one line fails, traffic may be delivered via the other switching concentrator and line.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is an overall system functional block diagram of a conversational video system in accordance with the present invention.

FIG. 2 is a functional block diagram of a typical central system network portion of the conversational video system of FIG. 1;

FIG. 3 is a block diagram of a typical host computer portion of the central system network of FIG. 2;

FIG. 4 is a block diagram of a typical computer node portion of the packet switching network of FIG. 2;

FIG. 5 is a block diagram of a typical switching concentrator computer portion of the central system network of FIG. 2 capable of providing local network control;

FIG. 6 is a functional block diagram of a typical terminal controller for use in the conversational video system of FIG. 1;

FIG. 7 is a functional block diagram of a typical display driver portion of the terminal controller of FIG. 6;

FIG. 8 is a more detailed functional block diagram of the VK8-A display driver of FIG. 7;

FIG. 9 is a diagrammatic illustration of a typical keyboard layout for the keyboard portion of a typical keystation for use in the system of FIG. 1;

FIGS. 10A-10F are diagrammatic illustrations of typical sample conversational video displays which may appear on the display portion of a typical keystation used in the system of FIG. 1;

FIG. 11 is a diagrammatic illustration of a typical display area layout for the display portion of a typical keystation used in the system of FIG. 1;

FIG. 2 is a diagrammatic illustration of the splitting of an input message to the concentrator computer into multiple packets;

FIGS. 13A-13P are diagrammatic illustrations of a typical conversational signal path in the system of FIG. 1 utilizing local network control for switching concentrators sharing a common node, with FIGS. 13A-13F relating to setting up a call, FIGS. 13G-13I relating to ending a call, and with FIGS. 13J-13P relating to leaving a message;

FIGS. 14A-14C are diagrammatic illustrations of the exchange of data records in the system of FIG. 1 during a typical conversation;

FIGS. 15A-15B are diagrammatic illustrations of the exchange of data records in the system of FIG. 1 during the provision of a subscriber page to subscribers on the CALL LIST;

FIG. 16 is a diagrammatic illustration of the structure of the Subscriber File in the system of FIG. 1;

FIG. 17 is a diagrammatic illustration of the main data structure in the host computer portion of the system of FIG. 1;

FIG. 18 is a logic flow diagram of the condition responsive message routing logic portion of the system of FIG. 1 in connection with the establishment of a conversation in response to a CONTACT REQUEST from a maker utilizing the CALL LIST facility of the aforementioned copending U.S. patent applications in which access to the SUBSCRIBER FILE in the host computer is required;

FIG. 19 is a logic flow diagram of the condition responsive message routing logic portion of the system of FIG. 1 in connection with the establishment of a conversation in response to a CONTACT REQUEST received for a taker utilizing the INHIBIT LIST facility of the aforementined copending U.S. patent applications in which access to the SUBSCRIBER FILE in the host computer is required;

FIG. 20 is a diagrammatic illustration of a typical sample CALL or CONTACT LIST video display which may appear on the display portion of a typical subscriber keystation used in the system of FIG. 1;

FIG. 21 is a diagrammatic illustration of a typical sample INHIBIT LIST video display which may appear on the display portion of a typical subscriber keystation used in the system of FIG. 1;

FIG. 22 is a logic flow diagram of the condition responsive message routing logic portion of a typical keystation terminal controller portion of the improved system of the present invention in connection with the processing of a CONTACT or CALL LIST within the terminal controller in connection with the establishment of a conversation in response to a CONTACT REQUEST from a maker utilizing the improved CALL LIST facility of the present invention;

FIG. 23 is a diagrammatic illustration of a typical sample improved CALL LIST video display which may appear on the display portion of a typical originating subscriber keystation upon viewing of the CONTACT or CALL LIST when the CALL LIST table is empty;

FIG. 24 is a diagrammatic illustration of a typical sample improved CALL LIST video display which may appear on the display portion of a typical originating subscriber keystation in response to the user insertion of an entry to the subscriber's CALL LIST;

FIG. 25 is a diagrammatic illustration of a typical sample improved CALL LIST video display which may appear on the display portion of a typical originating subscriber keystation in response to the user insertion of an interest message to the subscriber's CALL LIST;

FIG. 26 is a diagrammatic illustration of a typical sample improved CALL LIST video display which may appear on the display portion of a typical originating subscriber keystation in response to the CALL LIST call being accepted by a called subscriber on the CALL LIST;

FIG. 27 is a logic flow diagram of the condition responsive message routing logic portion of a typical keystation terminal controller portion of the improved system of the present invention in connection with the setting up of local tables within the terminal controller in response to a VIEW RESPONSE request in connection with the improved CALL LIST facility of the present invention with respect to the set-up of subscriber-created CALL LIST tables, with the same diagram also being applicable as a logic flow diagram of the condition responsive message routing logic portion of the terminal controller in connection with the setting up of local tables within the terminal controller in response to a VIEW RESPONSE request in connection with the improved INHIBIT LIST facility of the present invention with respect to the set-up of subscriber created INHIBIT LIST tables;

FIG. 28 is a diagrammatic illustration of the logical flow of messages in the improved system of the present invention with respect to the set-up of local CONTACT LIST tables in a typical keystation terminal controller;

FIGS. 29-32, taken together, comprise a logic flow diagram of the condition responsive message routing logic portion of a typical keystation terminal controller portion of the improved system of the present invention in connection with: the processing of a CONTACT REQUEST in the terminal controller of the present invention in connection with the checking for a CONTACT LIST request; the processing of a SKIP SUBSCRIBER CONTACT LIST request within the terminal controller in connection with the establishment of a conversation in response to a CONTACT REQUEST from a maker utilizing the improved CONTACT or CALL LIST facility of the present invention; and the processing of a DUAL CONTACT LIST request within the terminal controller in connection with the establishment of a conversation in response to a CONTACT REQUEST from a maker utilizing the improved DUAL CONTACT or CALL LIST facility of the present invention;

FIG. 33 is a diagrammatic illustration of a typical sample improved CALL LIST video display which may appear on the display portion of a typical originating subscriber keystation in response to the acceptance of a DUAL CONTACT LIST call;

FIG. 34 is a diagrammatic illustration of a typical sample improved INHIBIT LIST video display which may appear on the display portion of a typical originating subscriber keystation upon viewing of the INHIBIT LIST when the INHIBIT LIST table is empty;

FIG. 35 is a diagrammatic illustration of a typical sample improved INHIBIT LIST video display which may appear on the display portion of a typical originating subscriber keystation in response to the user insertion of an entry to the subscriber's INHIBIT LIST;

FIG. 36 is a diagrammatic illustration of a typical sample improved INHIBIT LIST video display which may appear on the display portion of a typical originating subscriber keystation in response to the recall of the INHIBIT LIST page by the originating subscriber;

FIGS. 37-40 are diagrammatic illustrations of typical sample video displays which may appear on the display portion of a typical subscriber keystation utilizing the improved INHIBIT LIST facility of the present invention;

FIGS. 41-43 are diagrammatic illustrations of the exchange of messages in the system of the present invention utilizing the improved INHIBIT LIST facility of the present invention, with FIG. 41 relating to INHIBIT message flow, FIG. 43 relating to a PSEUDO-ACCEPT, and with FIG. 43 relating to END CONTACT on an inhibited call;

FIGS. 44-45 are logic flow diagrams of the condition responsive message routing logic portion of a typical keystation terminal controller portion of the improved system of the present invention in connection with the improved DEAL KEY facility of the present invention;

FIG. 46 is a diagrammatic illustration of the order of events relating to a typical DEAL KEY transmission between two subscribers in the improved system of the present invention including the type of typical video display produced thereby the present invention;

FIG. 47 is a diagrammatic illustration of a typical DEAL KEY text statement description in the improved system of the present invention.

FIG. 48 is a diagrammatic illustration of the message flow between concentrators showing a common switching node in the prior systems of the aforementioned copending patent applications incorporated by reference herein in their entirety;

FIG. 49 is a diagrammatic illustration, similar to FIG. 48, of the message flow between the switching concentrators of the present invention showing a common switching node utilizing the local network control of the present invention;

FIGS. 50-54 are diagrammatic illustrations of various potential network configurations for nodes and the switching concentrators of the present invention utilizing the local network control of the present invention;

FIG. 55 is a diagrammatic illustration of the basic software structure for a typical switching concentrator of the present invention capable of providing the local network control of the present invention with the hardware structure of this switching concentrator being shown in FIG. 5;

FIG. 56 is a logic flow diagram of the condition responsive message routing logic portion of a typical switching concentrator of the present invention having the software structure of FIG. 55 for providing the local network control of the present invention, with the same diagram also being applicable as a logic flow diagram of the condition responsive message routing logic portion of a typical node in connection with the local network control of the present invention;

FIG. 57 is a diagrammatic illustration of a typical exemplary message flow in connection with the completion of a call and transmission of data packets between connected keystations in the improved system of the present invention employing the switching concentrators and local network control of the present invention; and

FIGS. 58-79 are diagrammatic illustrations of a data flow analysis of the PSP or packet switching processing control program which is retrievably stored in a typical switching concentrator computer of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

Referring now to the drawings in details and initially to FIGS. 1 and 2 thereof, an overall system functional block diagram of a conversational video system, generally referred to by the reference numeral 30, in accordance with the present invention is shown. As will be described in greater detail hereinafter, the presently preferred system 30 of the present invention is preferably similar to the system previously described in the aforementioned copending patent applications, and particularly with the system described in the application entitled "Improved Conversation Video System", with the exception that the concentrator computers described therein are preferably replaced by the presently preferred switching concentrator computers or switching concentrators which provide local network control so as to switch or route conversational messages between callers sharing the same node facility directly between the switching concentrators without the necessity of having to go through the common node. Thus as shown and preferred in FIG. 1, the conversational video system 30 of the present invention preferably includes a central system network 32, to be described in greater detail hereinafter with reference to FIG. 2, and a plurality of subscriber locations with two such subscriber locations 34 and 36 being shown by way of example in FIG. 1 although, of course, any plurality of subscriber stations can be utilized in the conversational video system 30 of the present invention. As illustrated in FIG. 1, the central system network 32 preferably includes a host computer 38 which, as will be described in greater detail hereinafter, serves as the traffic control manager for the central system network 32 and is preferably a conventional computer such as a Digital Equipment Corporation PDP11/70. The host computer 38 is preferably connected to a packet switching network 40, which, as illustrated in FIG. 2, preferably comprises a plurality of computer nodes with two such nodes 42 and 44 being shown by way of example in FIG. 2. The packet switching network is preferably connected to the presently preferred switching concentrator computers located at the various geographic locations close to the various subscribers with two such switching concentrator computers 46 and 48 being illustrated in FIG. 1 as being associated with subscribers 34 and 36, respectively. As will be described with respect to FIG. 2, and FIGS. 48-79, these switching concentrator computers 46, 48, if located at the same site as the associated computer node may be directly connected thereto as well as to each other; however, if located at a remote site from the computer node, then they will be connected to each other at the same site and to the particular computer nodes in the packet switching network 40 and to any remote switching concentrators sharing this computer node via conventional modems. The switching concentrator computers 46 and 48 also preferably receive retrievable data from a retrievable data-base such as data-bases 50 and 52, respectively, which provide supplementary data for retrieval and display at the various subscriber locations 34, 36 by way of example. The associated switching concentrator computers are preferably connected to the various subscriber stations, such as 34, 36 via conventional modems, such as modems 58 and 60 for switching concentrator computer 46 and modem 62 for switching concentrator computer 48, to the subscriber locations 34, 36, respectively, with modem 58 being connected via telephone land line 64 to another conventional modem 66 and therefrom to a terminal controller 68, to be described in greater detail hereinafter with reference to FIGS. 6 and 7, as well as with references to FIGS. 22-47 in connection with the improved CALL or CONTACT LIST, INHIBIT LIST, and DEAL KEY features of the improved system 30 of the present invention. As will be described in greater detail hereinafter with reference to FIGS. 22-47, the terminal controller, 68 by way of example, in the improved system 30, plays an important role in controlling the routing of messages to and from the subscribers for which it is responsible without having to rely each time on the SUBSCRIBER FILE stored in the host computer 38. The terminal controller 68 is in turn connected to a plurality of subscriber keystations with each terminal controller preferably being capable of servicing, by way of example, up to 6 such subscriber keystations. Each keystation, such as keystation 70 illustrated in FIG. 1, preferably includes a keyboard 72, associated keyboard logic 74 and a cathode ray tube display screen 76 for display of supplementary data and conversational data. As will be described in greater detail hereinafter, the keyboard 72, together with the keyboard logic 74 provides the conversational data to the terminal controller 68 which acts as the interface between the keystation and the central system network 32 to enable conversational video messages to be transmitted and received in a real-time interactive environment. As further shown and preferred in FIG. 1, each terminal controller, such as terminal controller 68, also includes an associated printer 78 for providing a hard copy of the video conversation which has been displayed at the particular keystation through which the conversation has been conducted, such as keystation 70 by way of example. By way of example, subscriber station 34 is shown as having two terminal controllers, terminal controller 68 and terminal controller 80, each of which preferably has 6 associated keystations, with only 3 such keystations being illustrated in FIG. 1 by way of example for terminal controller 68, namely keystations 70, 82 and 84 and with only 2 such keystations 86 and 88 being illustrated by way of example for terminal controller 80 which is also associated with a separate printer 90. Terminal controller 80, like terminal controller 68 is preferably connected to switching concentrator computer 46
via a conventional modem 92 and a telephone land line 94. Similarly, at subscriber station 36, at least one other separate terminal controller 96 is provided for controlling up to 6 keystations with, again, for purposes of illustration, only 2 such keystations 98 and 100 being shown in FIG. 1. In addition, a separate printer 102 is also associated with terminal controller 96 which is, in turn, connected to switching concentrator computer 48 via another conventional modem 104 and a telephone land line 106. Assuming switching concentrator computers 46 and 48 are of the same site, they are in turn, directly connected together as shown in FIGS. 1 and 2. If they were located remote from each other, but still shared a common computer node 44, they would then preferably be connected to each other via a conventional modem. FIG. 2 illustrates such a situation in which switching concentrator computer 110 is located at a site remote from switching concentrator computers 46 and 48 but, nevertheless, shares common node 44. Thus, switching concentrator computers 46 and 48 but, nevertheless, shares common node 44. Thus, switching concentrator 110 is connected to switching concentrator 46 via modems 105-107 and telephone land line 109, and to switching concentrator 48 via modems 111-113 and telephone land line 115. As will be described in greater detail hereinafter, the switching concentrator computers 46, 48 for example, are preferably special purpose conventional computers such as Digital Equipment Corporation PDP11/34 operating under a packet switching procesing program, or PSP, such as illustrated in FIGS. 58-79, and the respective terminal controllers, such as 68, 80 and 96 are preferably special purpose computers such as Digital Equipment Corporation PDP8/420A which preferably contain a special purpose conversational video control program to be described in greater detail hereinafter.

Referring now to FIG. 2, a more detailed block diagram of the central network 32 of FIG. 1 is shown. It should be noted that the central system network 32 illustrated in FIG. 2 is merely exemplary of one possible network configuration although many other possible network configurations for providing conversational video may be accomplished without departing from the spirit and scope of the present invention, with FIGS. 50-54 illustrating various other network configurations, by way of example, which are possible with the presently preferred switching concentrators of the present invention for providing local network control. Thus, as shown by way of example in FIG. 2, the packet switching network 40, as previously mentioned, preferably contains two computer nodes 42 and 44, such as conventional Digital Equipment Corporation PDP11/34 computers which are illustrated as being geographically situated at the same location although, of course, these nodes could be at different geographic locations and, moreover, any desired plurality of nodes at different locations could be provided in accordance with the conversational video system of the present invention. However, for the purposes of explanation, it shall be assumed that the central system network 32 has the configuration illustrated in FIG. 2. Moreover, it shall be assumed, for purposes of explanation, that the conversational video system 30 of the present invention is capable of providing world-wide conversational video to subscribers located at four different geographical country sites, such as London, New York, Paris, and Zurich, by way of example. In this regard, it shall be further assumed that the computer nodes 42 and 44 are located at one of these geographical country sites, such as London, as illustrated in FIG. 2. Each of these geographical sites preferably has its own associated switching concentrator computer, with Zurich, by way of example, having two separate switching concentrator computers at the same site to service two separate groups of subscribers in connection with two separate local data-bases. It shall be assumed that switching concentrator computers 46 and 48 are both located at Zurich in the example of FIG. 2 and that additional switching concentrator computers 110, 112 and 114 are located, respectively, at London, Paris, and New York in the example of FIG. 2. In addition, preferably each switching concentrator computer 46, 48, 110, 112 and 114 has its own associated data-base for providing retrievable supplementary data for display at the keystations associated with that particular switching concentrator computer. Thus, the London data-base is designated by reference numeral 120 and the New York data-base is designated by reference numeral 122. It should be noted that as illustrated in FIG. 2, the retrievable data-base may also be remotely located or shared such as in the instance where one of the Zurich data-bases 52 is also accessed by the Paris switching concentrator computer 112 via conventional modems 124 and 126. The switching concentrator computers 46, 48, 112 and 114 are shown as being remotely located from the computer nodes 42 and 44 and thus, are preferably connected thereto via conventional modems and telephone land lines, with switching concentrator computer 114 being connected to computer node 42 via modems 130 and 132 and telephone land line 134, with switching concentrator computer 112 being connected to computer node 42 via conventional modems
136 and 138 and telephone land line 40, with switching concentrator computer 48 being connected to computer node 44 via conventional modems 142 and 144 and telephone land line 146, and with switching concentrator computer 46 being connected to computer node 44 via conventional modems 148 and 150 and telephone land line 152. With respect to switching concentrator computer 110, assuming it is located at the same physical location as the computer node 44, then it may be connected thereto by direct connection. However, if the switching concentrator computer 110 is remotely located from computer node 44, then it would preferably be connected thereto via another pair of conventional modems 154 and 156, shown in dotted form, and a telephone land line
158 which, of course, would be replaced by a conventional wire connection in the instance where the switching concentrator computer 110 is located at the same physical location as the computer node 44. The various modems associated with the connection of the respective switching concentrator computers 110, 46, 48, 112 and 114 are illustrated in FIG. 2 in one block corresponding to a plurality of such modems with these blocks being labelled, respectively, with reference numerals 170, 172, 174, 176 and
178. In addition, as was previously mentioned, the presently preferred switching concentrator computers which share a common node are also preferably connected to each other, although as illustrated in FIG. 54, such switching concentrator computers may be connected together even if they share different nodes. In this regard, as was previously mentioned, switching concentrator computers 46 and 48 are directly connected together via line 123 while being connected to switching concentrator computer 110
via modems 105-107 and 111-113 and telephone land lines 109 and 115, respectively. Similiarly, switching concentrator computers 112 and 114 which share node 42 are connected together via modems 117 and 119 and telephone land line 121. Modems 58, 60 and
62 in FIG. 1 are just an example of such modems and it should be noted that preferably one modem is provided for each telephone line connection such as preferably one per terminal controller, not taking into account a stand-by or back-up situation in which an additional modem would be provided.

Referring now to FIG. 3, a typical hardware configuration for the host computer 38 is shown. Thus, as previously mentioned, the host computer may be a conventional PDP11/70 CPU having desired core, such as 256K or 512K words of core which, via a conventional Digital Equipment Corporation Unibus 200 is connected to associated direct access storage 202 and 204, such as an RX11 dual floppy disc and an RMO3 disc via a conventional interface therefor, such as an RWMO3 interface 206, for disc 204. In addition, a plurality of serial interfaces 208, 210, 212 and 214, such as a Digital Equipment Corporation DL11, are provided for interfacing the CPU 38 with various associated control consoles, such as interface 208 being utilized with the control console associated with start-up of the system, interface 210 being associated with the control console for the conversational video communication of the system, interface 212 being associated with the control of the packet switching network 40 and with interface 214 being associated with the control which enables identification of new subscribers to be put into the system so that they may be incorporated into the conversational video system 30. In addition, a conventional asynchronous serial line interface 216, such as a conventional Digital Equipment Corporation DMC11, is provided to connect the CPU 38 to the packet switching network 40 for transferring data and control information between the host computer 38 and the packet switching network 40
at a rate of preferably 56 kilobits per second. As shown in FIGS. 14-21, and as specifically described in greater detail in the aforementioned copending U.S. patent applications, the host computer 38 in conjunction with the associated terminal controllers 68, 80, 96, by way of example, is structured to provide the subscriber with the ability to specify in advance those other subscribers in the system 30 from whom the particular subscribers will not accept calls, termed INHIBIT LIST, as well as to specify in advance a plurality of subscribers to which a contact message is simultaneously sent with the first subscriber in the group which is free having contact established therewith, termed CALL LIST or CONTACT LIST. CONTACT LIST may also be employed by a subscriber to simultaneously transmit a subscriber prepared page to all of the subscribers on the CALL LIST. As will be described in greater detail hereinafter with reference to FIGS. 22-43, in the improved system 30 of the present invention, the various terminal controllers 68, 80, 96 preferably directly control the CONTACT LIST and INHIBIT LIST functions associated with their associated various subscriber keystations without having to access the SUBSCRIBER FILE stored in the host computer 38 each time as was required in the aforementioned patent applications employing the prior system of FIGS. 14-21. In addition, the terminal controllers provide a DEAL KEY function which, as will be described in greater detail hereinafter with reference to FIGS. 44-47, enables rapid confirmation of transmitted messges by the sending subscriber. For completeness, however, the prior system of FIGS. 14-21 will be described herein so as to facilitate a better understanding of the improvements obtained by the system of the present invention. Of course, if desired, the presently preferred switching concentrator computers of the present invention may be utilized with the prior system described in the aforementioned copending U.S. patent application Ser. No. 230,341, or the continuation-in-part thereof, although a more flexible overall system is provided when utilizing the ability of the terminal controllers to directly control the various CALL LIST and INHIBIT LIST functions.

Referring now to FIG. 4, a typical hardware configuration for a typical computer node, such as node 42, for example, is shown. Thus, as previously mentioned, the CPU is preferably a conventional computer, such as PDP11/34 having 124K words of store. The CPU 42 is preferably connected to associated storage and interface devices via a conventional bus 230, such as a Digital Equipment Corporation Unibus. As with the aforementioned host computer 38, the node computer 42 preferably includes additional storage 232 such as an RX11B dual floppy disc which is preferably used to boot the CPU42. In addition, a plurality of serial interfaces 234, 236 and 238, such as conventional Digital Equipment Corporation DL11 interfaces, are provided to interface with control peripherals such as the operator's console to start up the system, the printer primarily used for failure monitoring, and the operating control for the system, respectively. In addition, a multiple serial interface 240, such as a conventional Digital Equipment Corporation DV11 is provided for interfacing with other node computers such as node computer 44. Interface 240 is capable of servicing up to 8 lines and may be connected to remotely located computer nodes via modems, 242
and 244 for example, and telephone land lines. The transmission rate is 9600 bits per second to the other nodes. In addition, in the example of FIGS. 2 and 4, computer node 42 includes 3 asynchronous serial line interfaces 246, 250 and 252, such as a conventional Digital Equipment Corporation DMC11, for interfacing the CPU42 with the host computer 38, and switching concentrators 112 and 114, respectively, to enable communication between the CPU42 and the interconnected computers. With respect to switching concentrators 112 and 114, as was previously mentioned, they are interconnected to the computer node 42 via modems 138 and 132, respectively, and to each other via modems 117 and 119. With respect to computer node 44, since the concentrator computer 110 is, by way of example, located at the same site as computer node 44, no modem would be required between the corresponding asynchronous serial line interface and the switching concentrator computer 110. In addition, with respect to the interface 246 to the host computer 38, the data rate is preferably 56 kilobits per second. Lastly, the node configuration illustrated in FIG. 4 also preferably includes a cyclic redundancy check calculation unit 254, such as a conventional Digital Equipment Corporation KG11, connected to the computer bus 230 for conventionally checking the integrity of the transmitted packets. It should be noted that with respect to the interface to the switching concentrators at interfaces 250 and 252, this is perferably at a data rate of 9600 bits per second.

Referring now to FIG. 5, a typical hardware configuration for a typical presently preferred switching concentrator computer, such as switching concentrator computer 46 is shown by way of example. Thus, as previously mentioned, the switching concentrator computer 46 CPU is preferably a conventional special purpose computer such as a Digital Equipment Corporation PDP11/34 having 124K words of store and which is preferably connected to various associated interfaces and storage via a conventional bus 270 such as a Digital Equipment Corporation Unibus as was previously discussed with reference to the configurations of FIGS. 3 and 4. Again, as was true with respect to the configuration of FIG. 4 for a typical node computer 42, 3
serial line interfaces, 272, 274 and 276, such as conventional Digital Equipment Corporation DL11 interfaces are provided for essentially the same purposes as interfaces 234, 236 and 238 previously described with reference to FIG. 4. Similarly, a cyclic redundancy check calculation unit 278 is also provided for essentially the same purpose as cyclic redundancy check calculation unit 254 in FIG. 4, such as a Digital Equipment Corporation KG11, and dual floppy disc storage 280, such as an RX11B, is provided for essentially the same purpose as the storage 232 in FIG. 4. An asynchronous serial line interface 282 is connected to the bus 270 for interfacing the switching concentrator computer 46 with its associated computer node 44 through modem 148
and telephone line 152 with the data being provided at a data rate of 9600 bits per second. Another asynchronous serial line interface 283 is connected to the bus 270 for interfacing the switching concentrator computer 46 with switching concentrator computer 48 via direct line 123 while still another asynchronous serial line interface 285 is connected to the bus 270 for interfacing the switching concentrator computer 46 with switching concentrator computer 110 through modem 107 and telephone land line 109 with the data, in each instance, being provided at a data rate of 9600 bits per second. In addition, the switching concentrator configuration also preferably includes a plurality of multiple asynchronous serial line interfaces 284, 286, 288, such as conventional Digital Equipment Corporation DH11 interfaces, each capable of supporting 16 lines which, via conventional modems, such as the modem configurations represented by reference numerals 172, 290 and 292, connect the switching concentrator CPU46 to the various subscriber terminal controllers, such as terminal controllers 68 and 80 for example. It should be noted that preferably one modem is provided for each of the 16 telephone lines associated with the respective interface
284, 286 or 288 and, in the example of FIGS. 1 and 5, modem configuration 172 includes modems 58 and 60 illustrated in FIG. 1. The data rate on each of the lines connected to the subscriber terminal controllers, such as controllers 68 and 80, is preferably 1200 bits per second. As was previously mentioned, and as will be discussed in greater detail hereinafter with reference to FIGS. 58-79, a packet switching process control program (PSP) is preferably permanently stored in ROM at the switching concentrator computer 46 although, if desired, it could be downstream loaded into core.

Referring now to FIG. 6, a functional block diagram of a typical preferred terminal controller configuration, such as a terminal controller 68 which acts as the conversational video communications interface between its associated keystations 70,
82 and 84, by way of example, and the switching concentrator computer 46 which interfaces the terminal controller 68 with the balance of the conversational video communication system 30 is shown. As shown and preferred in FIG. 6, the terminal controller
68 preferably includes a central processing unit 300, such as a Digital Equipment Corporation KK8A CPU and associated memory 302, 304 and 306. Memory 304 and 306 are preferably core, each comprising 16K words, such as provided by a conventional Digital Equipment Corporation MM8AB Core. Memory 302 preferably includes memory extension logic, power fail logic, and ROM, with this logic circuitry being conventional, such as Digital Equipment Corporation KM8A. As will be described in greater detail hereinafter, the control program for the terminal controller 68 which controls the conversational video communication between the associated keystations 70, 82, 84 and keystations located throughout the conversational video communications network 30 is preferably downstream loaded into core storage 304, 306, although, if desired, this control program could be permanently stored in ROM, assuming the ROM was of the appropriate capacity to store the control program. An example of a typical conversational video communications control program which is downstream loaded into core 304, 306 or which, as previously mentioned, could be permanently stored in appropriate ROM at the terminal controller 68 is provided below in Table A, written in PAL8 assembler language. This control program is an improvement on the control program contained in TABLE A of the aforementioned copending U.S. patent application Ser. No. 230,341, and the aforementioned application entitled "Conversational Video System Having Contact Selection Control", the contents of which, including said prior TABLE A are specifically incorporated by reference herein in their entirety. As noted below, and as will be described in greater detail hereinafter with reference to FIGS. 22-47, the improved terminal controller control program enables the preferred improved CONTACT LIST, DUAL CONTACT LIST and INHIBIT LIST functions to be performed by the terminal controller, as well as the aforementioned preferred DEAL KEY function, without having to access the SUBSCRIBER FILE 1000 of the host computer 38 each time as was true with respect to the prior CONTACT LIST and INHIBIT LIST functions referred to in the aforementioned patent application entitled "Conversational Video System Having Contact Selection Control."

TABLE A (See Attached Listing)

In the present example, where the above improved control program of Table A is downstream loaded from the switching concentrator computer 46, a terminal bootstrap program is stored in ROM 302. As was previously mentioned, this ROM 302 is contained in a conventional KM8A module. The bootstrap program is preferably responsible for loading the improved conversational control program of Table A into core 304, 306 as well as for loading other conventional executive programs into core 304,
306 which enable the proper operation of the CPU 300. An example of a typical preferred terminal controller bootstrap program stored in ROM 302 is provided below in Table B with this program also being written in PAL8 assembler language and being a duplicate of the listing contained in Table B of the aforementioned copending U.S. patent application Ser. No. 230,341.

TABLE B (See attached listing)

TABLE B __________________________________________________________________________ DEALING BOOTSTRAP PROIGRAM LISTING __________________________________________________________________________ 0000 FIELD 0 5400 *5400 SERVE 05400 5336 JMP NEXTCH Will only branch for transmit complete 05401 0536 JMP NEXTCH on correct line so no need to test 05402 0377 KASK 377 Can use last two transmit jumps for 05403 7774 KMFOUR -4 data as these flags never become set 05404 7000 SERVR0 NOP Timeout constant 05405 5350 SERVR1 JMP GETRID Check for correct line . . . 05406 7640 SERVR2 SZA CLA (Assume ACC 0-9 clear) 05407 5350 SERVR3 JMP GETRID This instruction is used to overlay SERFVR1 Fall thru when we are awaiting input & input occurs on line 0 or 1 05410 6705 YMSRD Read CHAR 05411 0202 AND MASK 05412 7421 MOL Hold CHAR in MO 05413 7701 ACL Restore and check 05414 1371 TAD KMSOH For SOH 05415 7650 SNA CLA 05416 5226 JMP SOHGOT Yes-Start data reception
05417 2017 ISZ ZAUTO7 No-Update count of CHARS 05420 5232 JMP STORE This section of code collects a packet and goes to load it if the CRC is valid 05421 7327 GETPKT WP0006 Set up dummy packet 05422 3377 DCA LENGTH Length . . . (Will be overlaid when packet is stored) 05423 1276 TAD OVRLAY 05424 3205 DCA SERVR1 Await input 05425 7340 WM0001 Ignore all but SOH (CT = -1) 05426 3017 SOHGOT DCA ZAUT07 Save data (CT = 0) 05427 6116 YRCCB Clear cyclic check register 05430 1366
TAD RCVPKT Set PTR - 1 05431 3011 DCA ZAUTO1 05432 7701 SOTRE ACL Get CHAR from MO and 05433 6114 YRCGB accumulate CRC 05434 7701 ACL 05435 3411 DCA I ZAUTO7 Save data 05436 1017 TAD ZAUTO7 See of all CHARS received . . . 05437 7040 CMA (Length = total number of packets CHARS; 05440 1377 TAD LENGTH Count = number of input CHARS -1) 05441 7740 SMA SZA CLA 05442 5262 JMP WAIT Packet not fully in so get more CHARS 05443 6112 YRCRL Check that CRC 05444 7640 SZA CLA is correct
05445 5221 JMP GETPKT Not O.K. 05446 6111 YRCRH 05447 7640 SZA CLA 05450 5221 JMP GETPKT Not O.K. 05451 1207 TAD SERVR3 Ignore input now 05452 3205 DCA SERVR1 Assume packet if a load packet 05453 1367 TAD SDATA Origin pair follows field byte 05454 3013 DCA ZAUTO3 Use ZAUTO3, not ZAUTO1; we use the latter for packing pkts as it is already set to safe default value. 05455 1203 TAD KMFOUR Set auto-index to number of 05456 1017 TAD ZAUTO7 pairs of six bit CHARS to 05457 7171 STD CIA RAR be processed. 05460 3017 DCA ZAUTO7 05461 5332 JMP LD2 Go test for no RIM data in packet Wait always entered with clear AC 05462 1204 WAIT TDA SERVR0 Set timeout for 10 sec (don't bother clearing ZA as will make little difference to timeout) 05463 3012 DCA ZAUTO2 05464 6701 BACK YMSAB Wait for flag set 05465 2010 TIMEIT ISZ ZAUTO0 and increment timeout 05466 5264 JMP BACK if data not yet received 05467 2012 ISZ ZAUTO2 05470 5264 JMP BACK If timeout error fall thru to retry (Will never get timeout error if entered wait from outpkt) This is bootstrap start address RETRY 05471 7300 TAP111 WKLEAR 05472 6710 YMSCD Initialise KL8-A 05473 7203 WP0100 and set up KG8 05474 6115 YRCLC control register 05475
7300 WKLEAR 05476 1365 OVRLAY TAD NEGLIN 05477 7040 CMA Swap lines (Alternates 05500 3365 DCA NEGLIN 0, -1) 05501 7332 WP2000 05502 1365 TAD NEGLIN Assert request to send on new line and clear 05503 6711 YMSLC request to send on last line used 05504 7300 WKLEAR 05505 1364 TAD XLOCN Set up branch address . . . Only bits 0-8 used 05506 6712 YMSLB 05507 7300 WKLEAR 05510 1207 TAD SERVR3 Ignore input by overlaying SERVR1 05511 3205 DCA SERVR1 with a JMP GETRID instruction 05512
2016 ISZ ZAUTO6 05513 5307 JMP .-4 Wait 50 ms for the clear to send Send boot request 05514 1352 TAD HELLO Send HELLO message . . . 05515 5335 SENDPK JMP OUTPKT (MSG includes CRC & terminating word) Pack RIM 05516 1413 LDNEXT TAD1 ZAUTO3
05517 7106 CLL RTL 05520 7006 RTL 05521 7006 RTL 05522 1413 TAD1 ZAUTO3 05523 1370 -1 KM0201 Assume 8th bit always set (also COMPS link) 05524 7430 SZL 05525 5331 JMP LD1 05526 1371 TAD KMSOH 05527 3011 DCA ZAUTO1 05530 5332 JMP LD2
05531 3411 LD1 DCA 1 ZAUTO1 05532 2017 LD2 ISZ ZAUTO7 05533 5316 LOAD JMP LDNEXT Send RIM ACK On entry ACC = MSG PTR -1 05535 3011

OUTPKT DCA ZAUTO1 MSG includes CRC & IS terminated by a constant in range 3000-6377 05536 7300 NEXTCH WKLEAR 05537 1365 TAD NEGLIN -or 0 05540 7043 CIA BSW 05541 7106 CLL RTL Form 0 or 400 for lines 0, 1 respectively 05542 1411 TAD
1 ZAUTO1 05543 7510 SPA 05544 5221 ENDPKT JMP GETPKT End of xmission - NB ACC not = 0 05545 6704 YMSXD Xmit 05546 7300 WKLEAR 05547 5262 JMP WAIT Wait for xmission gone (Returns to NEXTCH & ignores input, if any) 05550 5265 GETRID YMSRD
05551 5265 JMP TIMEIT 05552 5552 HELLO HELLO 05553 0001 SOH 05554 0012 HIYPE 12 05555 0201 HCRC1 05556 0227 HCRC2 05557 5557 RIMACK RIMACK PTR & terminator of HELLO MSG 05560 0001 SOH 05561 0014 14 05562 0001 RCRC1 05563 0225
RCRC2 05564 5400 XLUCN SERVE PTR & terminator of RIMACK MSG 05565 0000 NEGLIN 0 05566 5574 RCVPKT PSTART 05567 5601 SDATA LENGTH +2 05570 7577 KM0201 -201 05571 7777 KMSOH --SOH 05572 0000 ZBLOCK .+200 & 7600-. *Zero Fill page __________________________________________________________________________

As further shown and preferred in FIG. 6, the terminal controller 68 also preferably includes conventional cyclic redundancy check logic 308, such as a Digital Equipment Corporation KG8 and a conventional multiple serial line interface 310, such as a Digital Equipment Corporation KL8A, for interfacing the terminal controller CPU 300 with the switching concentrator computer 46 via modem 66 at a rate of 1200 bits per second asynchronous, and for interfacing the terminal controller CPU 300 with the printer 78. In addition, the terminal controller 68 also preferably includes a display driver for each of the keystations, such as keystations 70, 82 and 84, associated with the terminal controller. Thus, since as previously mentioned each terminal controller is preferably capable of servicing up to 6 keystations, 6 identical display drivers 312, 314, 316, 318, 320 and 322 are provided with, for example, display driver 312 being connected to keystation 70, display driver 314 being connected to keystation 82 and display driver 322 being connected to keystation 84. Each of these display drivers 312 through 322 may preferably be of the type commercially available from Digital Equipment Corporation under the designation VK8A. Each display driver preferably provides video signals to the CRT associated with the keystation, such as CRT 76 for keystation 70, and receives input signals from the keyboard logic associated with the keystation, such as keyboard logic 74 for keystation 70, with the display driver 312 through 322, inclusive, being the interface between the CPU 300 and the individual keystations.

Referring now to FIG. 7, a typical video display driver 312 is illustrated in block form. Thus, the display driver 312 preferably includes a plurality of input gates 350 for receiving the eight data lines from the keyboard encoding logic 74, as well as for receiving a KEYBOARD PRESENT signal line also provided from the keyboard logic 74 to indicate to the terminal controller 68 that the keyboard has been switched on. In addition, the display driver 312 also includes conventional strobe logic
352, which receives a keyboard strobe signal from the keyboard logic 74, and control, address, and data registers 354, 356 and 358, respectively. Control register 354 preferably provides an alarm control signal to the keyboard for providing an alarm indication to the user. The address register 356 and the data register 358 are preferably associated with a display memory 360, such as a display RAM having 2048 bytes of memory. In reality, the display screen is preferably 80-by-24 and, accordingly, only the first 1920 bytes of the display RAM 360 are utilized to map 1-to-1 on to the display screen. The output of the display RAM 360 is provided to a conventional video signal generator circuit 362 which includes a character generator for providing a video display signal to the CRT 76 from the contents of the display RAM 360. As shown and preferred in FIG. 7, the input gates 350, strobe logic 352, control register 354 and address and data registers 356 and 358, respectively, are all connected to the CPU bus 370, such as a conventional PDP8 Omnibus. As was previously mentioned, the display driver 312 is preferably a conventional display driver such as VK8A commercially available from Digital Equipment Corporation and a more detailed block diagram of such a VK8A display driver is illustrated in FIG. 8 and corresponds to FIGS. 3-1 in the VK8A Maintenance Manual of January 1977 which may be referred to for further details on the operation of the VK8A display driver.

Referring now to FIG. 9, a diagrammatic illustration of a typical keyboard layout for the keyboard portion 72 of a typical keystation 70 for use in the conversational video system 30 of the present invention is shown. Thus, as shown by way of example in FIG. 9, the various keys of keyboard 72 bear legends associated with the function of type of message which the user or keystation 70 wishes to transmit through the keyboard logic 74 to the terminal controller 68, for example, for appropriate processing. As further shown and preferred in FIG. 9 the keyboard function keys are preferably divided into several functional types; namely mode keys 700 which select between a data base display mode, such as for displaying conventional data of the type commercially available from Reuters under the service designated as Reuter Monitor, and the conversational video communication mode which enables a user to carry on a two-way conversation with other users in the system 30; function and control keys
702 which are responsible for certain functional control commands; display and cursor control keys 704 which are responsible for controlling the display 76; and character control keys 706 which include certain character control functions including insertion of character data. The depression of a mode key 700 preferably causes subsequent input to be interpreted by the terminal controller 68 as being associated with that selected mode. With respect to the function and control keys 702, the effect of each function key is to some extent preferably dependent upon the mode which has been selected. Thus, the key 703 labelled VIEW indicates to the terminal controller 68 that the characters which are subsequently being input via the character control keys 706 are to be interpreted as a request for a display. As will be described in greater detail hereinafter with respect to FIGS. 22-47, and particularly with respect to FIGS. 27 and 33, this VIEW key 703 is utilized in connection with the set-up of subscriber created CALL LISTS and INHIBIT LISTS which are locally stored in the terminal controller in the improved system 30 of the present invention. The key labelled CONTACT indicates to the terminal controller 68 that the characters which are subsequently input via the character control key 706 specify the party or subscriber or CONTACT LIST members with whom a conversation or other contact is desired. The key labelled ACCEPT indicates to the terminal controller 68 that the character which is subsequently input via the character keys 706 specifies the call that the user wishes to accept from the incoming call list. The key 705 labelled INSERT indicates to the terminal controller 68 that the characters which are subsequently input via character keys 706 are to be interpreted as an insert whose function depends on the mode selected; for example, in the data or Monitor mode the characters would be interpreted as an insert to the data base 50 and in the conversational mode the characters which were input would be interpreted as an insert to the user line of the display 76 allowing preparation of conversational text without transmission at the time of preparation of these characters to the other party to the communication; whereas in the INHIBIT LIST or CONTACT LIST made, the characters which were input would be interpreted as an insert to the subscriber's INHIBIT LIST or CONTACT LIST, such as referred to in FIG. 35 OR 29, respectively. This key 705 may also be used to prepare messages to be left or interest messages as will be described hereinafter. The key labelled CANCEL indicates to the terminal controller 68 that the characters which are subsequently input by character key 706 are describing an entity to be cancelled. The key labelled RESET resets a keystation within the current selected mode such as clearing the input characters displayed on the insert line and the associated message line. In addition, as is readily available from the Reuter Monitor system, news alerts can be provided, and, if such a data base is used to provide data to the system 30 of the present invention, the RESET key, if qualified by an earlier ALRTS key from key group 704, may be used to clear a news headline, with the display 76 reverting to the mode before the ALRTS key was depressed. The key labelled RECLL provides a control signal to the terminal controller 68 requesting the recall of the previous display. The key labelled INTPT initiates a control signal to the terminal controller 68
which, in the conversational mode, initiates an interrupt message giving control of the conversation over to the party who initiated the interrupt message. This function is to be described in greater detail hereinafter. The key labelled END CONT initiates a control signal which results in the termination of a current conversation in the conversational mode. The key labelled CHGE CNV initiates a control signal which causes transfer, in the conversational mode, between conversations if two conversations are being carried on simultaneously by a single user 70 in which instance, as will be described in greater detail hereinafter, the first conversation area 502 and the display area 504 are then utilized in the user display 76. In addition, as will be described in greater detail with reference to FIGS. 31-32, with respect to the ability to carry on two conversations simultaneously, the two conversations can be set-up with a single call using the improved DUAL CONTACT LIST function of the improved system of the present invention. The key labelled PRINT initiates a control signal to the terminal controller 68 which forces printing of the current display at printer 78.

With respect to the aforementioned key labelled ALRTS in key group 704, this key initiates a special sub-mode which allows control of the news headline area if present, the alerts area and the incoming calls area of the display 76. In this regard, when this key is initially depressed the alerts area is selected and control moved between the aforementioned three areas by pressing 1, 2 or 3 respectively. When the alerts or incoming calls area of the display 76 are selected the area may preferably be scrolled using the line and page control keys 704. With respect to these keys the LINE BACK and LINE FWD keys move the display up or down by one line and preferably affect only conversational dialogue displays, alerts and incoming calls, whereas the PAGE BACK and PAGE FWD affect the display of the next or previous page. With respect to the cursor control keys, these control the cursor, with the HOME key placing the cursor on the first position of the insert line and with the TAB key placing the cursor just after the last character on the insert line, with these keys only affecting the cursor in the insert line. The key labelled TRANSMIT, in the conversational mode, transfers control of the conversation to the other party. This key is also used to indicate the completion of entry of text into the insert line. With respect to the key labelled ABBRV, this key relates to the insertion of text on the user line, and particularly to the insertion of such text containing abbreviations. When this key has been depressed, the terminal controller 68 will examine the inserted message after it has been completed to determine if any of the character strings correspond to abbreviations contained in the look up table of the terminal controller
68. If so, these character strings are expanded into their corresponding full text prior to transmission. With respect to the key labelled END LINE, this key initiates the starting of a new line of conversational video text without transferring control to the other party to the conversation. With respect to the key 726 labelled HIGHLIGHT, in the conversational mode, depression of this key causes the previous line, or the current line if it has been started, to be highlighted by asterisks on the right of the text in the print out. With respect to the key 727 labelled DEAL, in the conversational mode, depression of this key 727 results in a double asterisk confirmation of receipt of the sent message or line transmission adjacent the message or line being confirmed and functions similarly to the END LINE key as will be described in greater detail hereinafter with reference to FIGS. 44-47. Lastly, the pressing of any of the graphic keys results in the character being displayed in the position indicated by the cursor and the cursor moves on to the next position. It should be noted that the cursor normally remains in the insert line except during conversations when characters may be input directly into the display 76 for transmission to the other party.

Referring now to FIG. 11, a diagrammatic illustration of a typical display area layout for the display portion 76 of a typical keystation 70 is shown. The display 76 preferably displays 24 lines each of 80 characters. Preferably the display 76
is divided into a plurality of pre-defined areas with certain of these areas clearly designated by providing lines 720, 722, 724 and 726. Thus, the screen or display 76 is preferably divided into a first conversation area 502 defined by lines 722, 720
and 726, with line 722 being at column 65, with line 720 being at column 14 and with line 726 being at column 22 to define a first conversation area of 8-by-64. In addition display 76 also includes a display area 504 defined by lines 722 and 720 which display area is preferably 13-by-64 and may display either the contents of a second conversation or retrieved data. Another area of the display is the incoming calls area 500 defined by lines 724, 722 and 726. The incoming calls area is preferably
11-by-15, with the last three lines of the incoming calls area 500 being special areas relating to a display of a message *MORE* if more calls cannot be shown, a display of the number of calls queued, a display of the number of left messages not cancelled, and a display of the last call received. The display 76 also includes an alerts message area 510 for display of alerts messages, with this area preferably being 6-by-15 and being defined by lines 722 and 724. Lastly, the bottom display area
506 of the display 76 includes a user insert line, a message area and a system status area with the bottom area 506 displaying the mode, the function, and the user insert line, which user insert line preferably comprises positions 11 to 80 of row 23, and with the mode of the system being displayed relating to the conversational mode including the CN1 or CN2 designation where CN1 is the conversation displayed in the first conversation area 502 and CN2 is the conversation displayed in the display or second conversation area 504. With respect to the message area, positions 1 to 48 of row 24 provides space for responses to inputs to the system from the keyboard 72 with this message area being cleared when text on the insert line is transmitted. Typical responses appearing on the message line are ACCEPTED and INVALID. Position 50 of row 24 preferably shows the transmission state of the last message in the current mode with W indicating waiting for transmission and T indicating waiting for a reply. This transmission state is preferably blank in the CN1 and CN2 modes, except when leaving a message. Positions 52 to 57 of row 24 preferably show the first 6 characters of the last page requested in the current mode, which page can be requested again by pressing the RECLL function key on the keyboard 72. Positions 59 to 60 of row 24 preferably show the status of the second conversation in the event this second conversation is not then currently being displayed in display area 504, with the first character being a single letter representation of the status, such as busy, queued, free, receive, send, transfer, ended or off system. With respect to the aforementioned alerts contained in area 510, preferably five alerts of up to 15 characters can be displayed in chronological order, with the most recent five received by the controller 68 preferably being displayed although the controller 68 is preferably capable of retaining an additional 12 alerts which may be scrolled into view by pressing the ALRTS key on the keyboard 72 and the LINE or PAGE keys. Preferably, as illustrated in FIG. 11, the most recent or last alert is not scrolled and always occupies the bottom line or area 510. With respect to the aforementioned incoming calls area 500, this area preferably contains brief details of the incoming calls and their interest messages, with the calls being shown in chronological order, with the oldest at the top of the area and with the latest call being displayed in lines 21 and 22. It should be noted, however, that the incoming calls do not have to be selected by the called party in the order in which they are displayed. Line 20 is preferably used to show the incoming call status. Preferably, if a news alert is received, it will be displayed in three lines below the display area 504, namely in rows 14 to 16 and positions 1 through 64. If a conversation is occupying this portion of area 502, then the heading of the conversation will be moved to row 17 to allow for display of the news alert. As was previously mentioned, this news alert may be reset.

Referring now to FIGS. 10A through 10F, these figures illustrate typical examples of conversational video displays which may appear on the display 76 of a typical keystation used in the conversational video system 30 of the present invention. As was previously mentioned, in order to conduct a conversational video communication, the keyboard 70 must be in the conversational mode. In this mode, each keystation is preferably capable of controlling two conversations simultaneously and, if the user decides to initiate such a second conversation, the details will be displayed on his display 76 in the display area 504 and will override and cancel any other display in this area 504. Displays, however, may be called up in any mode while a second conversation is in progress and will then temporarily suppress the display of the second conversation in area 504. These displays will themselves be overridden and cancelled when the second conversation is subsequently selected. The format of the display of the second conversation in area 504 is preferably identical to that of the first conversation and occupies lines 1 to 8 of the display area 504. If one conversation contact has been executed, a subsequent contact is assumed to be a request for a second conversation with control being passed back to the first conversation by depressing of the key labelled CHGE CNV on the keyboard 72 which key may thereafter be used to transfer at any time between the two conversations. If the first conversation is completed while a second one is still in progress, the second conversation still remains in the display area 504. Typical call headings which would be displayed under various conditions are illustrated in FIG. 10A with each of these call headings being appropriately labelled. Each subscriber is preferably assigned a unique four character short name and the user wishing to contact another subscriber merely presses the CNTCT key on his keyboard 72, then the short name of the subscriber and the TRANSMIT key. In making this contact, the calling party may use an abbreviated form of address, may add a two character reference code to the called name, which code is intended to indicate which of the called subscribers keystations the caller wishes to contact, or he may indicate a CONTACT or CALL LIST call with or without the requested skipping of selected subscribers in the CALL LIST for a given call, or he may add a 14 character interest message to his call to indicate the reason for his call. This interest message is displayed in his conversation display as his first message in the conversation and is shown in the incoming calls area 500 of the display 76 of the party being called and then in his conversation display once the incoming call is accepted. Calls which are received by a subscriber are preferably assigned a letter on receipt and are displayed in the incoming calls area 500 of all keystation screens associated with that subscriber. Calls normally occupy one line of the incoming calls area 500 and are preferably displayed, as previously mentioned, in time order with the letter assigned to the call, the four character short name of the calling subscriber and, if present, the two character reference code indicating the particular keystation that the caller wishes to contact. If an interest message is sent with the call, it preferably appears on the next line of the incoming calls area 500 indented one space. When the user accepts a call by pressing the ACCEPT function key on his keyboard 72 followed by the letter identifying the call which he wishes to accept and the key labelled TRANSMIT, the system displays, on his insert line, the message CNV ACCEPT A assuming that call A is accepted, and in the conversation area 502 for the first conversation or the display area 504 for a second conversation, the conversation heading in exactly the same format as for the contacting subscriber except for the substitution of the word "FROM" for the word "TO" to indicate that the calling party originated the call. If an interest message was included with the contact, this is preferably displayed as the first message of the conversation and the contacted party is then expected to reply with a second message. The status of the call will reflect this. The acceptance of the call is also signalled to the terminal controller of the calling party and the status of the called party's display is updated to indicate either that he should await a message, such as if he sent an interest message, or that he should start the dialogue or conversation. In addition, the accepted call is cleared from the incoming calls area 500 of all keystations associated with that subscriber. With respect to conversations dialogue, input messages are preferably displayed in the conversation area 502 for the first conversation, starting at position 4, with the user keying in the information at his own rate. The message is then transmitted in packets as it is being typed in, with the packets of the message preferably being transmitted if a space character is encountered after the input of the tenth character from the start of the line or end of the previous packet, if no space is encountered after the tenth character but the 15th character has been input, if the END LINE key has been depressed either in conversation text or to release prepared text in the insert line, if the 61st character of a line is typed, this character overflowing to the next line and automatically forcing an end of line condition, if the control is moved to the insert line by pressing the INSERT key or the ABBRV key, if the TRANSMIT key is pressed to indicate the end of the sender's message, if an interval of a predetermined period, such as 20 seconds, elapses since the last text transmission, or if the END CONT key is pressed. The completion of a message is preferably signalled by a change of status in the conversation header line of the sender's conversation from send to receive and vice versa for the recipient's conversation. While the user is awaiting receipt of a message he may prepare his next response on the insert line. He may also prepare a message for transmission when he is in control of the conversation. In either case, he enters the appropriate conversation mode CN1 or CN2 using the CNV mode and the CHNG CNV key if necessary and then presses INSERT. The system will then transmit any text up this point and move the cursor to position 11 of the insert line. The user may then enter up to 70 characters in the insert line and edit them as required, with this text only being released if the user presses TRANSMIT, END LINE or END CONT while he has control of the conversation. The text when released in this manner is transferred to the conversation area 502 or 504 if it is a second conversation, and transmitted to the other party, with the insert line being cleared. If the TRANSMIT key has been pressed, the text is regarded as forming the complete message and the conversation status changes to receive. The use of the END LINE key indicates that the user's message is not complete. The cursor is moved into the dialogue test at an appropriate point for input to continue. Further text may be added in the conversation or in the insert area if the insert key is pressed again. A correspondent who was waiting for a response from the other party may preempt control by pressing the INTERRUPT key, as previously mentioned, and any portion of text which has been received by the receiving party's terminal controller before the INTERRUPT key has been pressed is regarded as binding and is displayed on the recipient's display 76 as received message. The pressing of the key changes the status of his conversation from received to send and results in an interrupt message indicating how many characters have been received by the interrupted party. Receipt of this message changes the status from send to receive, clears any text after the interrupt point, and displays the message *INTERRUPT* on the next line. The interrupter is then in control of the conversation and can commence the transmission of his message. He may in turn be interrupted. The display of a conversation holds a heading and up to 7 lines of conversation, each of up to 60
characters, by way of example. The first character of each line indicates whether the line was transmitted or received. The text of lines sent preferably start at position 4, lines received being indented to position 5. The most recent message is preferably at the bottom of the area and the oldest at the top. When the area is full, the uppermost lines are preferably moved off the screen leaving space for newer messages. Earlier parts of the conversations may be examined by using the LINE and PAGE function keys on the keyboard 72. It should be noted that when a conversation is scrolled so that the current line is not on display, this is indicated on the display by display of the word SCROLL on the heading line. A user may print a current conversation using the PRINT function key on the keyboard 72 at any time. If he does so, the conversation up to that point is released for printing on the printer associated with the terminal controller and, effectively, a new conversation is started within the same call and with the same party, the user's screen is cleared, and portions of the conversation which took place before pressing the PRINT key cannot be recalled by use of the LINE and PAGE keys. It should be noted that preferably conversations of a normal length of 300 to 500 characters may be completed without the necessity of printing the conversation before it is completed.

By way of example, with respect to the aforementioned abbreviations function, standard abbreviations may be employed such as by using the symbol A for the word "AT" by using the symbol B for "I BUY", by using the symbol FF for "FRENCH FRANCS", and by using the symbol * for "MILLION", then the expression "AT 79 I BUY 10 MILLION FRENCH FRANCS" may be provided in the following abbreviation: "nA79B10*F". Simple conversational messages in accordance with the above principles are illustrated in FIGS. 10A through 10F and are essentially self-explanatory with the legends provided underneath. It should be noted that the above exemplary displays are assuming that the conversational video system 30 is being used in the money dealing market in which money dealing rates are proposed and accepted by the subscribers to complete transactions. Of course, the conversational video system 30 of the present invention may be employed in any type of rapid video communication between subscribers and particularly where more than one conversation is desired to be carried on at a given time or where it is desired to provide supplementary data which may be retrieved along with the conversational text, particularly where the data could be useful in connection with the transaction being carried out through the video conversation function of the system 30. As was previously mentioned, the display of retrievable data may preferably be conventionally accomplished by a conventional data retrieval system, such as the Reuter Monitor and need not be explained in any further detail. At this point, in order to provide a basis for comparison, the operation of the prior system described in the aforementioned copending patent application entitled "Conversational Video System Having Contact Selection Control" shall now be described in greater detail below, assuming for purposes of explanation that the conversational video system is being used in a money market dealing environment. Thereafter, the improved system 30 shall be described in greater detail with reference to FIGS. 22-79. As was previously described and as will be noted below one of the more apparent differences between the prior system and the improved system of the present invention, apart from addition capabilities such as DUAL CALL LIST and DEAL KEY, resides in the ability of the terminal controller of the present invention to control CALL LIST and INHIBIT LIST functions without having to access the SUBSCRIBER FILE 1000 of the host computer 38 as was required in the prior system operation.

As was previously described, the terminal controller, such as terminal controller 68, provides the interface between the users or subscribers and the central system network 32. Preferably, the terminal controller 68 interface to the network is based on a port table in the controller 68 control program enumerated above in Table A herein for the improved system of the present invention, and in Table A of the above application referring to the prior system. The various ports relate to communication with the associated switching concentrator 46 herein, separate ports corresponding to communication with the data base 50, other ports relating to communication with the host computer 38 through the packet switching network 40, such as, by way of example, with respect to the aforementioned CALL LIST and INHIBIT LIST features or facilities to be described in greater detail hereinafter with reference to FIGS. 14-21 for the prior system and with respect to FIGS. 22-43 for the improved system of the present invention, and with 12 ports being reserved for the 12 possible video conversations that can be held on the 6 keystations supported by the terminal controller 68, such as keystations 70, 82 and 84, by way of example. As was previously mentioned, the packet switching network 40 is preferably a conventional type of packet switching network such as one conforming to the standardized X25 packet switching protocol, as is also true for the packet switching process (PSP) control program stored in the various switching concentrator computers 46, 48, 110, 112, and 114 of the present invention, and is preferably used to provide logical connections, by way of example, between the various switching concentrator computers, such as 46 and 48, and between the switching concentrator computers 46, 48 and the host computer 38. The system is designed so that preferably one of the logical connections between the switching concentrator computer 46 and the most computer 38 through the packet switching network 40 or by direct connection to another switching concentrator computer, such as, for example, switching concentrator 48 or via modems 105-107 to switching concentrator 110 as will be described with reference to FIGS. 48-79, also carries all of the communication information between the terminal controller 68 and the host computer 38 as well as, in the example of FIG. 1 all of the communication information between the terminal controller 80 and the host computer 38 and any other terminal controllers which are associated with that particular switching concentrator computer 46. Thus, all of the common ports of the terminal controllers which are connected to a given switching concentrator computer 46 and which are associated with the host computer 38 use the same channel across the packet switching network 40, assuming no direct connection to another switching concentrator computer. Similarly, all of the video conversations that are directed from one switching concentrator, such as switching concentrator 46, to another switching concentrator, such as switching concentrator 48, are multiplexed across a common logical connection between the switching concentrators 46 and 48. The terminal controller, such as terminal controller 68, preferably contains answerback codes and user abbreviations which are employed in the conversational video system 30 of the present invention, as well as in the improved system of the present invention, copies of the INHIBIT tables or LISTS and CONTACT or CALL tables or LISTS. Thus, an answerback code would preferably be a 20 character text string identifying a particular subscriber, such as subscriber 34, and the user abbreviations are for abbreviated transmissions of various data so as to expedite the video communication, with a given terminal controller preferably containing up to a thousand characters relating user abbreviations to their corresponding full text expansion. The terminal controller 68 is preferably identified to the switching concentrator computer by a subscriber identifier and a unique controller number. During system 30 operation, the various multiple serial interface 284, 286 and 288, by way of example, associated with the switching concentrator computer 46 check a line whenever no traffic has been acknowledged for a predetermined period, such as five seconds. Each terminal controller acknowledgement confirms the identity of the line by preferably including a check byte in addition to the packet sequence number. If the checks fail, the connection is broken and an error condition is reported. The packets on the line to the terminal controller, such as terminal controller 68, may be at normal or high priority, to be described in greater detail hereinafter. Once a packet is being transmitted, it is preferably delivered before another is transmitted; however, the interface 284, 286 or 288 will preferably select high priority packets in preference to normal priority packets. The messages received by the switching concentrator computer 46 from the system 30 are preferably divided into 64 data byte packets for transmission to the terminal controllers, such as terminal controller 68, so that high priority packets can obtain access to the line in a reasonable time. The first byte of each packet to the terminal controller 68 preferably contains the port number of the connection and a bit indicating if this is the first packet of a message. In terms of the aforementioned priority, a video conversational message is preferably given a high priority in the system whereas data from the data base 50 is given a normal priority.

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