Information handling system and terminal apparatus therefor

Informaton for display at a terminal apparatus of a computer is stored in blocks the first part of which contains the information which is actually displayed at the terminal and the second part of which contains information relating to the display and which may be used to influence the display at the time or in response to a keyboard entry signal. For example, the second part of the block could include information for providing the complete address of an another block which would be selected by the operation of a selected key of the keyboard. The second part of the block could alternatively influence the format and/or color of the display at the terminal. When a block is read from the store of the computer the second part is retained in another store which may be located in the terminal or in the computer itself or perhaps both. The invention is particularly useful in reducing the complexity of the operating protocol of the computer.

BRIEF SUMMARY OF THE INVENTION 
This invention relates to an information handling system in which 
information is derived from a computer at a remote point and transmitted 
via the public telephone network to terminal apparatus. The invention also 
includes the terminal apparatus itself. 
It has been proposed to provide for domestic and/or business consumers a 
simplified form of computer terminal by means of which information stored 
in a computer can be obtained from it via the public telephone network. 
The form of the terminal is different from a conventional computer 
terminal, both in the simplicity of its operation and in the form of its 
display. The display is of the form of a page of data and is reproduced on 
a cathode-ray tube screen which may be part of a domestic television 
receiver or may be a special purpose apparatus for this function. Instead 
of a cathode-ray tube screen, a special purpose alphanumeric display may 
be used. Initially the data is displayed on the screen in the form of a 
sequence of progressively more detailed indices by means of which an 
operator is enabled to key-in to a key pad provided for the terminal 
numbers identifying a particular page of information which he requires. 
Since the system is to be operated by unskilled operators it is important 
that the key required be of self-evident nature and inevitably this will 
restrict the nature of facilities which the computer can provide. One such 
system is known by the name VIEWDATA, and in which the information 
provided by the computer is identified by a page number and when this page 
is keyed the whole of the data contained in that page is transmitted in 
coded form to the terminal where it is stored and displayed continnously, 
until the next page is received or the terminal switched off. 
Difficulties arise in such a system, however, because of the need to ensure 
the simplicity of operation of the terminal, bearing in mind the 
likelihood that the significance of particular keying inputs may need to 
be varied in dependence on the data being displayed. 
It is an object of the present invention to alleviate the above difficulty. 
According to one aspect of the present invention there is provided an 
information handling system in which information is transmitted to a 
terminal apparatus from a computer via a telephone line, the information 
being transmitted to the terminal apparatus in packets, each of which is 
displayed by the terminal apparatus as a page consisting of a plurality of 
parallel lines of alphanumeric characters and/or graphical data, the 
terminal apparatus including means for transmitting signals to the 
computer via the telephone line indicating which packet or packets of 
information are to be transmitted by the computer, wherein information is 
stored by the computer in blocks each of which contains a first part 
consisting of the packet of information in the form of coded groups of 
digits representing the characters or graphical data forming the page to 
be displayed and a second part containing in coded form details relating 
to the page of information which are not displayed, means being provided 
for storing the second part of a block when the first part is transmitted 
to the terminal apparatus. 
The details relating to the page of information may be retained in the 
computer, for example, in a special register provided for the purpose, so 
that inputs from the terminal apparatus can be used to select items from 
among the details as information or instruction data for the computer. If 
the system forms part of a public telephone network, it is necessary to 
provide a way of charging a subscriber's account for the block or blocks 
of information transmitted to his terminal equipment. It is envisaged that 
certain information may be provided at very low cost or possibly free, 
whereas other information such as, for example, latest stock market prices 
may be relatively expensive. In such a system the second part of a block 
may include an indication of the charging rate for information supplied in 
the first part, so that the computer and/or the terminal can be arranged 
to record the cost of the information extracted to be charged against the 
subscriber's account. 
The second part of a block may include software, that is programming 
information, for simplifying entries to be made by an operator on the 
basis of the information displayed to him by the terminal apparatus. For 
example, the page of information displayed may be an index or part of an 
index, and to simplify keying each item of the index displayed may be 
indicated by a single digit. When the digit against a desired item is 
keyed it may be used to select full addressing information from the second 
part of the block, which full information is transmitted to the computer 
to enable the selection of the desired item. The second parts of the 
blocks of information may alternatively be transmitted to the terminal 
apparatus and stored in a special register there. 
According to a second aspect of the invention there is provided a terminal 
apparatus for an information handling system in which information is 
transmitted from a computer to the terminal apparatus via a telephone 
line, the information being transmitted to the terminal apparatus in 
blocks each of which is displayable by the terminal apparatus as a page 
consisting of a plurality of lines of alphanumeric characters and/or 
graphical data, the apparatus including means for receiving blocks of 
information signals from a telephone line, storage means for storing a 
block of information signals, means for repeatedly reading at least part 
of the storage means, means for converting signals repeatedly read from 
the storage means into video signals, means for producing a prolonged 
visible display in response to the video signals, and means for 
transmitting signals to a telephone line indicating to a computer which 
block or blocks of information are to be transmitted, wherein the storage 
means has a first part for storing coded groups of digits representing 
alphanumeric characters or graphical data forming the page of information 
to be displayed, and a second part for storing the remainder of the block 
of information representing details relating to the page of information to 
be displayed. 
The terminal apparatus may include data entry means, such as a manual 
keyboard, and means responsive to information stored in the second part of 
the storage means for modifying signals from the data entry means before 
they are applied to the transmitting means. Alternatively or additionally 
signals read from the second part of the storage means may be selectively, 
in response to the data entry means, transmitted to the telephone line for 
addressing other blocks of information stored in the computer.

DETAILED DESCRIPTION 
The system shown in FIG. 1 has a computer 1 connected by a telephone line 2 
to terminal apparatus which forms the remainder of the figure. The line 2 
would of course include the telephone exchange equipment normally in a 
public telephone system, but this is not shown to avoid complicating the 
figure. The terminal apparatus has a changeover switch 3 connected to the 
telephone line 2 which enables a telephone apparatus 4 to be connected to 
the line 2 when the terminal is not in use. Isolation and protection 
circuits 5 connect a modem 6 to the switch 3. Alternatively, the switch 3 
and the circuits 5 may be replaced by an acoustic coupler for connecting 
the modem 6 to the telephone apparatus 4. The demodulated signals from 
modem 6 are applied to a memory A, reference 7, which is controlled by a 
memory control unit 8 repeatedly to produce coded output signals which are 
applied to a read only memory 9 which operates as a character generator to 
provide video signals for a display device 10 shown as including a 
cathode-ray tube. The memory control unit 8, the ROM 9 and the display 
device 10 are synchronised in their operation by a display control unit 
11. 
Inputs from an operator to the terminal apparatus are entered by means of a 
key pad 12 which is connected to a signal generator 13 producing signals 
which after modulation in the modem 6 are transmitted via the isolation 
and protection circuits 5 and the switch 3 to the line 2, and through that 
line to the computer 1. 
FIG. 2 is a diagram illustrating a block or "page" of information such as 
would be transmitted from the computer 1 to the terminal. The page 
consists of two parts, the first part being displayed information in 
response to which the display device 10 is operated, and the second part 
is hidden information which is related to the displayed information and 
may be used in various ways as described below. The displayed information 
consists of 960 bytes, each of eight bits, and may, for example, represent 
24 lines each of 40 characters forming an alphanumeric display. The hidden 
information consists of 64 bytes, each of eight bits. 
In the operation of the system shown, when a block of which is to be 
displayed is transmitted by the computer 1 to the terminal and routed to 
the memory A. The second part of the selected block is transferred to 
special memory B included in the computer 1 and associated with the input 
channel of the computer to which the terminal is connected. The memory 
control unit 8 repeatedly reads memory A which produces an eight-bit 
parallel output which is applied to the ROM 9. Each eight-bit parallel 
output from the memory A represents either an alphanumeric character or an 
element of a graphical display, using, for example, an ASCII code. The 
timing of the reading of information from the memory A is controlled by 
the memory control unit 8 and is synchronised with the scanning of the 
display device 10 and the operation of the ROM 9 by signals applied to the 
unit 8 from the display control unit 11, which times the operation of the 
ROM 9 and the scanning of the device 10, so that the information is 
displayed by the device 10 in the appropriate page format. 
If the information displayed is an index, then it is anticipated that the 
operator will operate one of the keys of pad 12 to indicate which item of 
the displayed index he wishes to receive. The complete reference (i.e. 
address) of the index items could be displayed on the screen and the 
operator could be required to press a number of keys on the pad 12 to 
select a particular item. However, it would be simpler for the operator if 
the items of the index displayed were simply numbered, say, from 1 to 9 so 
that all the operator had to do was to press a single key on the pad 12 to 
select a particular item. This could be achieved by applying a signal from 
the pad 12 to the computer 1 for selecting an address in the memory B, for 
transfer of the full address of the particular item selected to circuit 21 
of the computer. Any calculation or logical operations required could 
either be performed by the computer itself or in a special logic unit 
provided for the purpose. 
It will be appreciated that the second part of each block could have other 
uses, both for influencing the nature of the display produced and to 
reduce the complexity of keying required to communicate with the computer 
1. For example, the display could be of a game to be played by the 
operator and the reaction of the computer 1 to any particular key input 
would depend on the data displayed to the operator which represents the 
current state of the game. Information could be stored in the memory B to 
interpret the keying on the basis of the displayed information to feed a 
corresponding signal to the computer to enable it to respond to the 
operator's "move". 
An alternative to the embodiment described above is shown in FIG. 3 in 
which the memory B together with associated address and input and output 
circuitry is located in the terminal instead of in the computer. This 
means that the second parts of the blocks of information must be 
transmitted to the terminals when selected, and that the terminal must 
have means for selecting signals from the memory B for transmission to the 
computer when information stored in the memory B is to be employed. This 
alternative embodiment would have an advantage if the displayed 
information were in the form of questions, for example, of an educational 
programme, because the answers could be stored in the memory B and they 
could be compared with answers provided by the user and entered through 
the keyboard without the need for further communication with the computer 
1. 
In FIG. 3 components corresponding to those of FIG. 1 have the same 
reference numerals as in that figure. In FIG. 3, the terminal includes 
memory B 14 which is connected to receive memory control signals from the 
memory control unit 8 through a line 15, and produces output signals which 
are applied to memory B LOGIC unit 16 to which signals from the key pad 12 
are also applied. Lines 17 and 18 convey output signals from the logic 
unit 16 to the memory A 7 and the signal generator 13 respectively. 
Information to be stored in the memory B 14 is applied to it from the 
modem 6 via a line 19. Output signals from the key pad 12 are also applied 
to the memory control unit 8 along a line 20. 
Insofar as the operation of FIG. 3 is the same as that of FIG. 1 it will 
not be further described. When a block of information is received from the 
computer 1, the first part is stored in memory A 7 and the second part in 
memory B 14 under the control of memory control unit 8. If the information 
stored in the memory B is used to augment or modify address data from the 
key pad 12, the pressing of a key of the pad 12 at this time causes the 
unit 8 to select the appropriate information from the memory B 8 and apply 
it to the logic unit 16 where it is combined with the data from the key 
pad and the full address transmitted via line 18, the signal generator 13, 
and the modem 6 to the computer 1. 
Where an entry on the key pad 12 is in answer to a question, the entry is 
compared with the correct answer from the memory B in the logic unit 16 
and the appropriate response applied via the line 17 to the memory A for 
display. 
Although the invention has been described with reference to a specific 
embodiment it will be appreciated that modifications can be made to the 
system described without departing from the invention. In particular, the 
numbers of digits making up each part of a block of information may differ 
from those described. The memory B may be duplicated, with one memory B 
located in the computer 1 and the other in the terminal.