GB2035017A - Electronic apparatus for the display of information - Google Patents

Abstract

Apparatus for a user terminal station of a viewdata system has a short-code signalling arrangement. This enables the user to cause the apparatus to transmit signals to line characterising the telephone number of a data bank to which connection is required through the public telephone network or the identity of a "page" required for display by operation of a lesser number of keys than would otherwise be the case. A RAM 17 is loaded under control of microprocessor 5, over address/control bus 7 and data bus 6, by signals from keyboard 10 and/or the remote data bank. On further command by a selected short key sequence the RAM 17 is read, generating required signals which are passed via parallel to series converter 11 to line 6. <IMAGE>

Description

SPECIFICATION Electronic apparatus for the display of information This invention relates to electronic apparatus for the display of information and is more particularly concerned with apparatus of the kind in which the information to be displayed is signalled from a remote location in response to a request for such information signalled by the apparatus to the remote location.

Apparatus for a user terminal station of a viewdata system, for example the PRESTEL system operated by the British Post Office, is apparatus of the kind specified and the invention is more particularly, but not exclusively, concerned with apparatus for a user terminal of such a system.

In the PRESTEL system, for example, the apparatus at a user terminal is connected to a pair of telephone lines which extend to an exchange of the public telephone network. When the user wishes to call up information from a remote data bank for display, it is first necessary for a connection between the user apparatus and the data bank to be set up through the public network. Forthat purpose, the apparatus is caused to transmit to line signals (e.g.

"dial" impulses or tone signals) characterising the telephone number of the required data bank. When such a connection has been established and the user's identity checked (for the purpose of charging), the apparatus is caused to transmit information, preferably a sequence of decimal numbers, in digital form to signify to the data bank the identity (e.g. a "page" number) of information required for display.

The requested information for display is then transmitted by the data bank in digital-coded form and upon being received by the user apparatus is written into a data store thereof. The received data is held in the data store for as long as the required information is to be displayed and the apparatus has provision for deriving from the stored data a video signal for supply to the display unit (e.g. a cathode ray tube) of the apparatus.

The apparatus also includes a keyboard having a plurality of manually-operable numeric keys and the telephone number of a required data bank and the identity of information required for display may be signalled to line by operation of the keyboard. That does however involve the operation of a considerable number of keys and one object of the present invention is to provide apparatus in which the telephone number of a data bank and/or the identity of information which is frequently required for display may be signalled to line more easily.

One example of apparatus in accordance with the present invention for a user terminal station of the PRESTEL system will now be described with reference to the two figures of the accompanying drawings in which Figure 1 shows the complete terminal apparatus diagrammatically, and Figure 2 shows a typical arrangement of information stored by the memory of the terminal apparatus of Figure 1.

Referring to Figure 1 of the accompanying drawings, the terminal apparatus comprises a display unit 1 having a cathode ray tube (not shown) on the screen of which appears the "page" of information to be displayed at any time utilising conventional line and frame scanning. The items of information making up a page to be displayed are stored in binary coded form in a page store 2 and items are read from this memory in synchronism with the line and frame scanning of the cathode ray tube under the control of a store address and control unit 3. A page display system 4 has a character generator read-only memory (not shown) which converts information read from the page store 2 into the required monochrome video signal (or individual colour signals if the apparatus gives a colour display) for controlling the cathode ray tube.The page store 2, the store address and control unit 3 and the page display system 4 together with other items as will hereinafter be described) are connected to a microprocessor 5 by way of a common data highway or bus 6 (consisting of seven separate conductors) and a common address and control highway or bus 7 (consisting of eleven address conductors and five control conductors). The microprocessor 5, which may conveniently be an INTEL 8085, is programmed to control the operation of the remainder of the terminal apparatus and, for example, controls the writing of information to be displayed into the page store 2 and the reading of information from the store. As so far described, the terminal apparatus under consideration is already known and operates generally in the manner described in the complete specification of our U.K. Patent Application No.

36842/76.

The page store 2, the store and address control circuit 3 and the page display system 4 may respectively be formed by integrated circuits type MA414(two off), MA401 and MA400 all supplied by GEC Semiconductors Ltd.

Bidirectional data signalling between the terminal apparatus and a remote location (at which there is a data bank capable of supplying binary data in respect of pages of information to be displayed in response to a request identifying the required page in binary form) is by means of a telephone line (not shown) connected to a pair of terminals 6. Signalling in both directions utilises the frequency shift keying (FSK) form of modulation, information from the remote location being signalled at a data rate of 1200 bits per second while information sent in the opposite direction for requesting a page is signalled at a lower data rate of 75 bits per second.

A modem 7 is connected to the terminals 6 by way of a transformer 8 and is arranged to handle signalling in both directions. When signalling a page of information to be displayed, the modem 7 supplies a binary signal carrying the required data in serial form to a serial-to-parallel converter 9 in which, under the control of the microprocessor 5, in turn supplies in parallel signals representing the eight bits characterising each item of information to be displayed (for example an alpha-numeric character) to the microprocessor 5 via the conductors of the data bus 6. The microprocessor then passes on those again via the data bus 6, to page store 2 which is arranged to store each item of information for sebsequent display.

It may be mentioned here that the microprocessor 5 periodically interogates the various other units connected to the buses 6 and 7 via the address and control bus 7 and, whenever such a unit indicates that it has data for transfer to another unit, transfer is effected underthe control of the microprocessor 5 by first passing the data from the first unit to the processor and then rerouting that information to the second unit (as identified by address signals on the bus 7), in both cases the appropriate data signals being passed in parallel over the data bus 6.

A request for a particular page of information to be displayed may be signalled to the remote data bank by operation of a numeric keyboard 10 at the termi nal under consideration. Upon each operation of a key of the keyboard 10, binary signals representing the selected decimal digit to be signalled are passed in parallel via the data bus 6 and the microprocessor 5 to a parallel-to-series converter 11 which supplies a serial binary signal characterising the character to the modem 7 for onward transmission.

When it is required to access the remote data bank for the purpose of displaying information, it is first necessary for the terminal apparatus to be con nected through the telephone network to the data bank. For this purpose the terminal apparatus must transmit to the telephone line signals (either in the form of "dial" impulses or multi-frequency tones) carrying the telephone number of the data bank. In the example of terminal apparatus being described, this is achieved by means of a calling unit 13 in response to operation of keys of the keyboard 10.

Thus, upon each operation of such a key, binary signals representing the selected key, are passed to the calling unit 13 which is then controlled bythe microprocessor 5 to cause the required succession of signals to be applied to the telephone line con nected to the terminals 6. If the telephone network responds to impulse type signals, the necessary loop dis-connect impulses are obtained by operation of a relay 14 which opens and closes contacts 15 in cir cuit between the terminals 6 as showrr.inlffiedraw- ing. Alternatively, if the telephone network responds to multi-frequency signals, the relay 14 is not needed and the calling unit 13 supplies the appropriate tone signals (via the path shown by a broken line 16) into the audio output circuit of the modern 7.

Upon the connection through thetelephone net work to the remote data bank being set up, the data bank sends back a signal to the calling terminal requesting that terminal to identify itself for chargirrs purposes. The identity of the terminal is stored by a memory 17 as a multi-decimal-digit number (or other combination of alpha-numeric characters).

When the terminal is required to identify itself, each decimal digit (or other character) is automatically read in turn from the memory 17 under the control of the micro-processor 5 and is passed via the data bus 6 and the converter 11 to the modem 7 which causes the decimal digit value (or character) to be signalled over the telephone line to the remote data bank.

The memory 17 is a volatile semi-conductor mem ory of the electrically alterable random access type.

Such a memory is sometimes known as a readmostly memory (RMM) or as an electrically alterable programmable read only memory (EAPROM). When the apparatus is first installed at the terminal in question, the identity of the terminal is written in to the memory 17. This may be achieved underthe control of the microprocessor 5 by operation of the keyboard 10.Preferably, however, at least part of the terminal identification (as stored by the memory 17) is obtained by establishing a connection from the terminal apparatusto apparatus at a remote location, transmitting signals to the location to request terminal identificaflon by the user operating a predetermined sequence of keys of the keyboard 10, and recording in the memory 17 the terminal iden tffications sent back from the remote location, all these operations at the terminal being performed under the control of the microprocessor 5.

The apparatus has provision for the memory 17 to benowered (either fromthe mains or from a rechargeable battery) when the apparatus is not actually in use so as to enable the information written into the memory to be retained. It will, of course, be appreciated that new terminal identifications information has to be written into the memory 17 if the apparatus is moved to anotherterminal of the PRESTEL system.

Theelectricallyalternblememory 17 is also used to store information other than the identity of the terminal which may be called up and signalled to a line on a "short-code dialling" basis by the user of the terminal apparatus operating one or few keys of the keyboard 10. The otherinformation stored by the memory 17 includes the telephone numbers of the PRESTEL and other remote data banks to which access required from time to time (thereby avoiding having to use the keyboard 10 in the manner previouslydescribed everytime such access is required)! and the identity af pages of information (e.g. the "Financial" page and the "Weather" page) which are frequently requested for display.To provide these facilities, the memory 17 is a 256 x 4 bit store, the storage being divided into sixteen segments in which are respectively stored the terminal identification, three telephone numbers and twelve viewdata page numbers as shown in Figure 2 of the a#companying drawings, each segment having pro vision to store up to#sixteen decimal digits in binary coded form.

The keyboard 10 also has four named keys (not shown) marked "VIEWDATA", "PROGRAM", "PAGE TRANSMIT', and "CLEAR" and two further keys (marked respectively with an asterisk and a hash symbol) in addition to the numeric keys previously mentioned. Upon each of these keys being pressed, signals representing a unique eight bit code are generated and passed in parallel to the microprocessor 5 via the bus 7. The manner in which the microproces sor 5 responds to the four named keys will now be described.

When the VIEWDATA key is pressed, the tele phone line connected to the terminal apparatus under consideration is seized (by looping the line as when a conventional telephone instrument goes "off-hook") and the microprocessor 5 commences to time a five second period. If, before the end of that period, the user presses one of the keys "0", "1", or "2", the appropriate one of the three telephone numbers stored by the memory 17 is read from that memory and passed to the calling unit 13 for use as previously described. If, however, no such key is pressed before the end of the five second time-out, it is assumed that the user wishes to be connected to the PRESTEL bank and the microprocessor 5 causes the relevant number to be passed from the memory 17 to the calling unit 13.

To write the telephone number of a remote data bank into the memory 17, the key PROGRAM is pressed and this is followed by pressing the appropriate one of the keys "0", "1" and "2" (to identify the segment within the memory 17 in which the telephone number is to be stored) and then the numeric keys in respect of the required telephone number which may have upto sixteen decimal digits. At the end of this sequence the 'hash' key is pressed to signify to the microprocessor 5 that instructions for writing a telephone number into the appropriate segment of the memory 17 has been completed whereupon the desired operation takes place.

For the purpose of writing a page number into the memory 17, the sequence is to press the key PROG RAM, the 'asterisk' key and one or more keys in respect of a number in the range "0" to "11" (to identify the segment of the memory 17 in which the page number is to be stored). This is followed by again pressing the 'asterisk' key (to signify that the segment identification has been completed) and a plurality of further numeric keys of the keyboard 10 in respect of the relevant page number. Finally the 'hash' key is pressed to signify that the entry has been completed.

Alternatively the number of a page of information which is currently displayed by the display unit 1 may be stored by the memory 17 for easy recall of that page at a later time. In this connection it will be appreciated that the PRESTEL system as presently envisaged is such that the first line of each displayed page contains the page number at twelve predetermined character positions so that, with the apparatus under consideration, the page number (of uptotwelve decimal digits) of a displayed page is stored at the appropriate storage locations within the page store 2. The microprocessor 5 may be instructed to write the number stored at those locations of the store 2 into the memory 17 by pressing the PROGRAM key followed by the 'hash' key and the numeric key (or keys) identifying the appropriate segment of the memory 17 as before. The sequence is completed by again pressing the 'hash' key.

When the user wishes to call up for display a page the full number of which is stored by the memory 17, it is merely necessary for him (after establishing connection to the remote data bank) to press the PAGE TRANSMIT key followed by the key (or keys) of the "short-code" number (in the range "0" to "11") identifying the segment of the memory in which the page number is stored and the 'hash' key.

Upon this occurring, the microprocessor 5 reads the page number from the memory 17 and causes sign alscharacterisingthe required page number to be transmitted to line via the converter 11 and the modem 7.

To clear down a call established to a remote data bank, the key CLEAR is pressed.

Claims (5)

1. Electronic apparatus for the display of information signalled from a remote location in response to a request for such information signalled by the apparatus to the remote location, said apparatus comprising a pair of terminals for connection to a two-way transmission line, a display unit, a data store for storing in digitally-coded form information to be displayed by the display unit, means to write data into the data store in response to signals applied to the pair of terminals and carrying information to be displayed by the display unit, means to derive from the data stored by the data store a video signal for supply to the display unit to control the display, and a short-code signalling arrangement to enable the user to initiate signalling to line, said short-code signalling arrangement comprising a random access memory having a plurality of storage segments, a keyboard having a plurality of manually-operable keys, means responsive to operation of a sequence of keys of the keyboard to enter into the memory at a segment identified by one or more of the operated keys information in digital form required subsequently for signalling to line, and means responsive to operation of a further sequence of keys of the keyboard to supply to the pair of terminals for transmission to line signals carrying the information stored by the segment of the memory identified by one or more of the operated keys.

2. Apparatus according to Claim 1 wherein some segments of the memory are arranged to be used to store the identity of information which may be required for display by the apparatus to enable that identity to be signalled as aforesaid.

3. Apparatus according to Claim 1 wherein the apparatus has provision to write the identity of information stored at any time by said data store for display by the apparatus into a segment of the memory to enable that identity subsequently to be signalled as aforesaid to recall the information in question for display.

4. Apparatus according to Claim 1, Claim 2 or Claim 3 wherein at least one segment of the memory is arranged to store for signalling as aforesaid the telephone number of a remote data bank to which connection may be required.

5. Apparatus according to any preceding claim wherein a further segment of the memory is arranged to be used for storing the station identity of the apparatus and the apparatus is arranged to supply signals to the pair of terminals for transmission to line characterising that identity as stored by the memory.