The present invention relates to a device of the type described in the preamble to claim 1.

Presently, a great problem is the inability to prevent unauthorized persons, from a terminal connected to a data communication network, from connecting into a terminal connected to the network. Even if the coupling numbers to the various terminals- are only given to those authorized to connect to them and even if a whole series of so-called passwords, i.e. series of numbers and letter combinations entered from a terminal seeking to be connected, the numbers and passwords can easily go astray quite simply because the user writes them down because they are difficult to remember.

Another disadvantage of transmission via a σompu- ter network is that the connection between terminals coupled to each other via the net is maintained during practically the entire time during which there is a dialogue between the terminals. This in turn places heavy requirements on the capacity of the network to be able to transmit all the desired traffic without excessive waiting times.

With the increasing number of terminals being hooked-up to the network there is an increasing risk that the expansion of capacity of the net will not be able to keep pace if the traffic is processed in the present manner.

There is thus a need for a method and a device for computer communication via a computer network, whereby the use of the computer network takes a much shorter time than at present, when the network is used continuously between the communicating stations as long as the communication is taking place. It is true that this use often takes place on a time-sharing basis, but the line is kept open between the communicating stations

throughout the entire communication. A very large pro¬ portion of the time for the communication is occupied by questions and responses concerning passwords.

Many computer communications taking place between different terminals connected to the network, are of a relatively simple nature, e.g. making changes in certain specific data in one terminal from another terminal and monitoring the state of certain data, or performing certain simple transfer operations which are of the same type each time. For example, one might desire, from a home computer terminal, to enter a terminal in a bank to check, ones account and/or transfer funds from one account to another.

The invention achieves significant simplification of the data transfer via the computer network or stan¬ dard computer communications with predetermined terminals with a device which has the characterizing features dis¬ closed in claim 1. Further features of the invention are disclosed in the subclaims. The invention will be described in more detail below with reference to the accompanying drawings, of which

Fig 1 shows schematically a block diagram of the ^" terminals provided with the device according to the invention connected to a computer network;

Fig 2 shows schematically a block diagram of the command processor, which is a part of the device accord¬ ing to the invention, and the units which are controlled by the processor; Fig 3 shows schematically a block diagram in more detail than that shown in Fig 1 of a terminal with the device according to the invention connected to a computer network and another terminal;

Fig 4 shows schematically a time diagram of a computer communication between a terminal provided with the device according to the invention and two counter- terminals;

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Fig 5 shows a schematic time diagram for work stations connected to a terminal provided with the device according to the invention in a hypothetical case of simultaneous request for entry into the network; and Figs 6 and 7 show in the form of block diagrams examples of units included in the device according to the invention for adaption to transfer to various types of computer networks connected to the network which the terminal is connected to. The invention is primarily intended for terminals connected to public computer networks, e.g. Datex in Sweden. The connection to the computer network should preferably be done with a DCE unit (Data Circuit- terminating Equipment) of DCΞ-X type and particularly with interface X.21 or X.25.

As shown in Fig 1, a number of terminals 1,2,3, called House-1 , House-2, House-n, are connected to a public computer network (PDN) 4 via individual DCE units 5, 6 or 7. To each terminal 1 , 2, 3, a number of work stations 1.1, 1.2, 1. ; 2,2, 2.m and'n.1, n.2, n.m, called Home-1 , Home-2, etc. are coupled. The number of work stations at each terminal does not need to be the same. Furthermore, a number of terminals 8-10 function¬ ing as data banks, called DB-1 , DB-2, DB-n, are coupled to the computer network 4 via individual DCE units 11 , 12 and 13 respectively. The terminals 8-10 are in this case counterstations to which the terminals 1-3 can connect in to extract the data stored therein. Each terminal 8-10 can have a number of work stations 8.1, 8.2, 8.p; 9.1, 9.2, 9.p and 10.1, 10.2, 10.p.

The home-work stations can be microcomputer units in the homes of private persons, said units being con¬ nected in one manner or another to one of the house terminals, which functions as a local station and is coupled to the public computer network 4 via a DCE unit. The house-work stations can also be industrial depart¬ ments.

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Each house terminal 1 , 2, 3, is according to the invention provided with a special command processor CP and special circuits and memories which it controls and extracts information from. Each home-work station can also be provided with an extra processor portion HCP, which is coupled to the command processor CP. The command processor CP controls the process execution of all modules in HCP.

Fig 2 shows a command processor 14 and its peri- pheral equipmen . In a permanent memory 15 there is a monitor routine for the processor 14. Below all of the permanent memories will be called ROM memories even if, in addition to pure ROM type memories, they can also be of PROM and EPROM type. The monitor routine continually senses whether a command from one of the home-work stations is present or not. As soon as a command occurs, the monitor routine tells the command processor KP to execute automatic connection to a specific work station in a counter-terminal such as one of the data banks DB-i, where the i stands for an undetermined "integer. In accordance with the invention there are a number of ROM memories 16-19 called ROM-TF-1 , ROM-TF-2 ROM-TF-n. According to the concept of the inven¬ tion, an operator at a home-work station should be able to subscribe to a completely predetermined service in a completely predetermined data bank. This service can, for example, consist of, when coupled to the data bank, of being able to look at the balance in a completely determined account in a bank and possibly also at the same time be able to transfer a sum entered at the home-work station to another account, which can also be determined already at the time of subscription. An example of such a transaction carried out with the device according to the invention will be described below in connection with the descriptio'n of Fig 3.

The command processor unit has thus in practice a number of free sockets for insertion of ROM memories.

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When an operator has decided to subscribe to a certain service, he/she receives a preprogrammed ROM memory, which can be plugged into one of the free sockets. The data which have been programmed into these ROM-TF units include on one hand all of the necessary data for con¬ nection to a specific data bank, such as couplingnumber, link coupling dialog, such as block heading and block ending in each transmitted data block and questioning routines, high-level dialogs, such as command words and several different types of passwords to both enter the data bank and then be forwarded to a work station con¬ nected thereto, and, on the other hand, which completely determined transactions which may be carried out, such as the accounts from which the balance may be given and transfers made, and those accounts to which transfers may be made. Each selected ROM-TF unit opens an indepen¬ dent command process in CP which awaits positive or negative process execution. This means that errors in an ROM-TF unit do not disturb the executions of other commands, such as when an operation according to one of the other ROM-TF units has been requested by a home¬ work station.

Disruptions in one data bank do not disturb the data transmission with other data banks. Erroneous operation in a system register which has been coupled into, immediately shuts off the command process and informs the operator. Nor is the operation carried out ^" when there is an error in the computer network or a DCE-unit. Each home-work station has a home-command proces¬ sor KCP, which can either be a special processor unit connected to a microcomputer or include the microcompu¬ ter itself at the station provided with a special pro¬ gram read into the computer. Furthermore, the home-work station is provided with some other equipment, such as a keyboard, visual display unit, and printer. These HCP-modules 20 cooperate with the command processor 14

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in the terminal.

The command processor 14 also controls a number of other modules, which are necessary to carry out a desired transaction, such as connecting module 21, dis- connecting module 22, character-sending module 23, character-receiving module 24, RAM-memory 25 for storing received characters and secrecy protection modules 26. A number of the modules listed here can be included in a single unit even if they are shown here individually for the sake of illustration.

The monitor routine 15 decides whether the com¬ mand from an HCP is present or not and initiates the command process (.CPR) , which is specified in the command specification (3C) of the selected ROM-TF-unit. The actual execution then follows, which will be described in more detail in connection with Figs 3 and 4.

More specifically, a transaction performed by a person at a home-work station can proceed as follows (see Fig 3) . The person connects to the house-terminal by for example pressing a special key to start the home- computer command processor HCP or by feeding in a speci¬ al program in his computer. The HCP 27 is then in commu¬ nication with CP 28, the monitor routine 15 of which jumps from an idle loop to the actual program execution. It is then sensed which ROM-TF-units are plugged into the command processor unit and which the home-work station in question has subscribed to, and a so-called menu is shown on the operator's visual display unit 31. ROM-TF 29 can for example be the subscribed service of upon request showing the balance in certain specific bank accounts at a specific bank and ROM-TF 29 can for example be the subscribed service of showing the balance for one or more credit cards.

The operator selects for example the service which is programmed into the ROM-TF 29 by pressing a key. Then the entire connection takes place to the counter- station 32, which can for example be US Bank of America,

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with the request sent entirely automatically via the computer network 33, which can for example be Datex with transfer to US Tymnet, in accordance with the pro¬ cedure which will be described below in connection with Fig 4. The response is stored in the RAM-character receiving unit 25, and the information stored there is shown on the visual display unit 31 and is possibly printed on a printer 36. By virtue of the fact that the entire procedure of connection and disconnection takes place entirely automatically, the period of connection and consequently the use of the net can be made quite short. The connection in this case was for the purpose of obtaining information programmed into a specific memory space in another station connected to the σompu- ter network.

Fig 4 shows an example of a transaction accord¬ ing to the invention where an operator at a home-work station wants to both make a purchase order at a first data bank DB-1 and thereafter be coupled directly to another data bank DB-2 to give an order for payment of the purchase articles. In this case it is assumed that such a transaction is to be done relatively often and therefore, the operator has subscribed to a type of co¬ ordinated transaction which can be stored in a single ROM-TF-i, where the i stands for the i-th ROM-TF-unit. This transaction includes both information which is to be transferred to the different data banks stating for example type of article, number, and the sum to be transferred from a specific account to another specific account, and the information obtained in registers in the receiving station such as estimated delivery date, account balance and the like.

As shown in Fig 4, this transaction is carried out in the following manner. An HCP-station is activat- ed. The command processor CP 14 scans the ROM-TF-unit. The operator at the HCP-unit selects the appropriate subscription and enters all the data which is to be

forwarded. These can for example be the number of articles of a certain type etc. These data are stored in a special memory space either- in the HCP- unit or in the CP-unit. - A connection is made to the appropriate ROM- TF-i by the monitor routine 15.

- Then the actual connection to the first counter-station DB-1 ' takes place with the aid of the connecting module 21 with data continually taken from the ROM-RF-i module in question via the DCE- unit of the house-terminal. The counter-station DB-1' DCE-station is called up using its subscrip¬ tion number. The connection module 21 waits for the READY signal and starts the dialog with the public computer network via the DCE-unit until the READY for DATA signal or CALL PROGRESS signal comes, latter which can be signals or non-positive disconnection.

- Upon response and connection between the DCE- units and the home-terminal and the counter-terminal, a number of distributed data dialogs DDD-1 take place, which can consist of a dialog between the two terminals, comprising both link coupling dialog, i.e. handshaking with the counter-terminal DB-i' when transferring the blocks of data, and high-level dialog such as command words and passwords in a usual manner per se in agreement with the control steps determined for the counter-terminal in question before one is given access to the terminal, i.e. the data package text, which consists of out-messages in the RAM-character receiving unit or in- essages in the command specification for the high-level dialog in question specified in the ROM-TF-i in question, the monitor routine initates high-level dialog HND or link level dialog LKD, and the HND can interrupt the command process if the counter- station DB high-level out-message is erroneous.

- The number of HLD-interactions is determinative for when a distributed data dialog is to be concluded with disconnection in the command processor K 14 and transferred to link coupling dialog LCD-i. The difference in relation to the usual process is that the passwords are only stored in the ROM-TF-unit in question and are not known to the operator, nor can they be echoed up on the visual display unit thereof. After connecting to the terminal DB-1 * , connec- tion to the correct work station connected thereto is effected by further distributed data dialogs, whereafter the data previously stored in HCP or CP is transferred from the character-sending module 24 and is read into a specific memory space and data is read out into another specific memory space. The data obtained is stored in the RAM-character.-receiving unit 25. This means that the distributed data dialogs DDD-i sequentially perform con¬ nection, link coupling dialogs, high-level dialogs and disconnection, and the counter-terminal DB-i in question performs the corresponding dialogs.

The disconnecting module 23 (see Fig 2) then dis¬ connects the connection. In order to speed this up, this can be effected in a manner known per se by giving ^" a special disconnecting word, such as DISCON or the like. The connecting module 21 then makes the next connection to DB-2 ' in order to give the payment order. The physic¬ al connection to the DCE-unit at DB-2 ' via the network is made by the link coupling dialog LCD-2. Then the high-level dialog .HLD-2' takes over, consisting of com- mand words and passwords to enter the terminal DB-2' , additional link coupling dialog to be able to be connec¬ ted physically to the correct work station connected to DB-2 ^• and additional high-level dialog to be allowed access to the work station and carry out the order. Disconnection then takes place by giving the special disconnection word. An indication is made that

the disconnection- has been completed and the information _f retrieved is displayed on the operator's play unit and/ or is printed by the printer.

The operation is concluded by a presentation level in HCP. The command process is always immediately interrupted if there should be any impermissibly long pauses, which are specified in the monitor routine 15 of the command processor 14 or in the ROM-TF-units T6-T9 in use. As can be seen along the ordinate access inFig 4, the entire procedure only takes a few seconds versus in the normal case several minutes, in which a transaction is carried out with the line connected from the time when the-operator has decided to carry out the transac- tion, i.e. during the entire giving of information and where the high-level dialogs are carried out by the operator himself.

It is obvious that for each house-terminal only one of the home-work stations connected thereto can be connected at one time to the network via the terminal and its DCE-unit. Since each connection to a counter- station only takes a few seconds, this does not present any problems; if a number of work stations request connection at the same time they are given priority according to a predetermined priority relationship and are placed in a queue as is shown in Fig 5 which shows a possible working procedure for a special house-terminal DCE-unit, using the device according to the invention for less than one minute. This assumes that each contact from connection to disconnection lasts approximately

10 seconds. During a first 10 second period the DCE-unit is kept ready for connection from the terminal and for receiving a request for connection from outside. Then the m-th home-work station Home-m" is connected. This takes place for approximately 10 seconds, whereafter the DCE-unit stands ready once again. Then the third and the second work stations request connection simultaneously.

The third work station Home-3" is given priority and is connected first for 10 seconds while the second work station Home-2" waits. Then the connection for the second work station Home-2" is established. During this period the first work station Home-1 " has requested connection and has been placed in the queue until the connection requested and established for Home-2" has been disconnected.

The waiting times are so short that the operators at the various work stations will in practice not have time to notice that they have been placed in a queue. This makes for low costs and a complete utilisation of the house-terminal DCE-unit. The special link coupling dialog LCD (see Fig 4) for the special intended connec- tion is written into each ROM-TF-unit. There are a number of standardized line procedures for link control. Samples of these are ISO (e.g. ISO 1745), ECMA, CCITT and ANSI. Different users use different systems.

When a special subscription has been made for connection to a special data bank, the link coupling dialog LCD specific for this special data bank, is specified in the ROM-TF-i-unit in which the subscription is written into.

Fig 6 demonstrates practical implementations for LCD which can be written into the various ROM-TF-units. Within each home-terminal the HCP, CP and PP (i.e. the physical interface, e.g. X.21, which represents the rules and agreements defining how an HCP is connected to the house-terminal DCE-unit and how connection, maintaining and disconnection take place) are compatible with each other. A method of obtaining complete compatibility within the data communication field is to use existing standardized link coupling dialogs LCD and storing them in the various ROM-TF-i-units or creating ones own norms and rules. LCD creates a unique interface to lower level PP ("physical" protocol) and to higher level (high-level dialog HCP ) . When embodying the device according to the

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invention it is suitable and practical to structure the monitoring routine 15 and the various ROM-TF-units so that when executing the various levels (HCP, CP, PP., LCD, HLD) , they are isolated from each, other in such a manner that the underlying levels are "transparent" to the overlying. This concept means among other things that it must be possible to make changes in any level written into a ROM-TF-unit, without affecting the PP- level. HCP provides a "uniform terminal" which the home- work stations must be adapted to. It is instead possible to freely select different link coupling dialogs LCD which, fit the application in question. This provides at the same time interchangeability and the possibility of communicating with, counter-stations (data banks DB) in other systems than ones own terminal. Fig 6 gives a practical example of this.

Fig 7 demonstrates the high-level dialogs within the device according to the invention.

As was mentioned above, the high-level dialogs " are written into the ROM-TF-units and are included according to the invention in the distributed data dia¬ log DDD-i, which controls the data package text exchange between HCP and the counter-terminal DB-i. The high- ^: level dialog specifies an interactive method for commu- nication transaction switching with register SR-i in the counter-terminal DB-i. The high-level dialog comprises the following specifications:

1) interactions which designate the number, and -

2) interactions which consist of pairs of irc-messages and responses from the counter-terminal as confirmation of the inrmessage.

The high-level dialog is started by the link coupling dialog, which is completely responsible for selecting responses and information transfer. The in-rmessages comprise the following types: a) number characters, text, no parameters b) number characters, text with fields for command

parameters, e.g. passwords, which can either be echoed or not echoed up to the visual display unit c) blind-number characters, artificial in-messages, which means that the counter-terminal DB starts dialogs or only sends out-messages.

The control of responses from the counter-terminal DB or the out-messages comprises the following types:

A) Number characters, address and control text which checks the response from DB, concludes the high-level dialog if the response is not correct or starts the next interaction within the scope of the distributed data dialog if the response is correct

B) blind-number characters which mean no control of the response from DB C) responses which are to contain presentation level for HCP.

The ROM-TF-units comprise a control portion which controls the transaction at high-level dialog. The high- level dialog can significantly reduce data transfer costs if the communication from one terminal to another h ^' as HLD on both sides of the link.

Computer technology has developed rapidly and therefore it is impossible to judge how much hardware and/or software is required for the command processor with its peripheral equipment. The LSI and VLSI techno¬ logies provide in this respect almost unlimited possi¬ bilities. Since in the device according to the invention, 'one no longer needs to rely on the memory of the user, the distributed data dialogs, and especially the high- level dialogs, can be expanded in a manner which is not possible at present, making the system extremely secure against unauthorized entry.

The device according to the invention is the first to provide all the preconditions for so-called system- dependent access, by virtue of the fact that various types of both link coupling dialogs and high-level dia¬ logs can be freely created in the various ROM-TF-units.

OMPI

Thus ali the home-work stations can communicate with all the counter-terminals DB, and the house-terminals are not of course an exception in this respect. It is true that the communications between the terminals according to this invention take place in a standardized manner with an ROM-TF-unit for each type of operation, but this is not especially limiting, since this type of communica¬ tion via computer networks is in any case the prevailing type. It is in combination with the interface X.21 with its coupling possibilities that the advantage of compa- tible, standardized transaction switching of the type achieved by the device according to the invention is most evident. The connections in the computer network are of the type house-terminal- to data bank terminal or house-terminal- to house-terminal. Both balanced and unbalanced communication links can be used.

Many modifications are possible within the scope of the invention.

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