CA1113188A - Text processing apparatus - Google Patents

Abstract

ABSTRACT

Text processing apparatus comprises a keyboard, a video display and a message buffer containing text to be displayed. When a word is too long to be contained on a display line, it automatically overspills and will form the first word on the next line. The mechanism for doing this includes a word boundary counter which keeps track of the starts of words as they appear in the message buffer.
This also allows such features as word underscore and word delete to be performed.

Description

`8 IMPROVEMENTS RELATING TO TEXT PROCESSING APPARATUS

This invention relates to text processing apparatus in which text is displayed on a video display.
Modern word processing apparatus use video displays tc present textual data to an operator as it is entered or for editing purposes. In the former case, as the operator keys characters into the apparatus, in much the same way as with a typewriter, the characters are presented on the video display:
when keying is complete, the operator can check what has been entered before the text is printed or, alternatively, trans-mitted to a remote screen for display or a central file for storage. When text is to be edited, the text is displayea on the screen and by using the keyboard to enter commands and text information, the operator can insert, delete or transpose text.
To improve operator productivity, it is convenient if text can be handled on a word-by-word basis rather than on a character-by-character basis. It is also helpful if the use of operator-entered carriage return commands can be minimized.
In the embodiment of the invention which will be des-cribed below~ characters can be deleted and underscored on a character-by-character basis. However provision is also madQ to allow the operator to delete and underscore whole words. Furthermore, in the apparatus to be described, carriage return codes are not normally entered by the operator. As will be seen, the operator only has to enter textual data and the apparatus will automatically take care of word over-spill conditions. In other words, if a word at the end of a line of text extends beyond the right hand margin, the apparatus will automatically transfer this word to the beginning of the next line of text.

Various attempts haye heen made in the past to ease the load on operators by giving assistance at the end of the line, for example by automatic hyphenation techniques, but generally these require relatively large and expensive equipment.
United States of America Patent No. 3,631,957 describes a system for producing output copy from an input tape. When word overspill is detected, a choice is given to the operator as to where to hyphenate. A variable-width control zone gives varying degrees of "raggedness" and need for hyphenation at the right hand margin.
United States of America Patent No. 3,688,257 discloses a formatted text display system in which end-of-line codes are inserted before words which are detected as causing Overspill. A register containing the address of the last space on the line is used to determine where the end-of-line code is to be inserted.
United States of America Patent No. 3,550,091 uses a counter to keep track of the last space on a line. Just before the right-hand-margin, words are entered on the next line as well as the current line. If a space is subsequently encountered before the margin, the word on the next line is deleted: if no space is encountered before the margin, the word entered on the current line is deleted.
None of this prior art apparatus discloses or susgests the use of a word boundary counter which contains the address of the next word with the provision of being able to "freeze"
the contents of the counter to allow text to be entered and/or edited as a complete word rather than on a character - -by character basis.

According to the present invention, a text processing ~ ~.

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apparatus comprises a keyboard for entering text and command information, a video display for displaying text, a message buffer for containing text to be~displayed, means for detecting the presence of a word delimiting character during cyclic scanning of said buffer to determine the start of a word in said buffer, a word boundary counter adapted to be loaded in succession with the address on the display of each word of text as said buffer is scanned, and means for preventing loading of said counter with the address of subsequent words when a processing operation is to be performed on a word and for allowing loading of said counter with the address of subsequent words when said processing operation is completed.
In order that the invention may be readily carried into effect, a preferred embodiment thereof will now be described, by way of example, with reference to the accomp-anying drawings, in which:-Figure 1 is a diagrammatic representation of a text processing apparatus, -Figure 2 is a block diagram illustrating a preferred embodi~,ent of the invention, Figure 3 shows the format of a command word, Figure 4 shows the format of text code, Figure 5 illustrates the use of temporary left margins with the apparatus of Figure 2, and Figure 6 illustrates how word overspill is accomplished in the apparatus of Figure 2.
Referring now to Figure 1, a text processing apparatus comprises a keyboard 1 by means of which text or commands can be entered, and a video display 2 on which text can be displayed during text entry or for editing. The text processing apparatus is connected to a controller 3 by a cable 4. Other displays and keyboards, not shown, can be .~
~ ~.

connected to the controller 3~ Attached to the controller is a printer 5, for example a so-called daisy-wheel printer or a line printer, by means of which text displayed on the display

2 can be printed. Also attached to the controller 3 is a text store 6, for example a magnetic disc store, in which text can be stored electronically for later recall. The stored text may include standard paragraphs etc. which can be incorporated into individual letters. Optionally, the controller 3 can be connected to a host central processing unit 7: such an arrange-ment would be useful, for example, for electronic mail purposes.
Typically, the video display 2 and keyboard 1 can beconstituted by an IBM (Registered Trade Mark) 3277 Model 2 Video display unit suitably modified as described below.
The controller 3 can be constituted by an IBM (~egistered Trade Mark) 3791 controller. Since the controller 3, printer 5, store 6 and host processor 7 are not directly relevant to an understanding of the present invention, they will not be --further described.
The keyboard 1 has a number of keybuttons 8 by means of which alphanumeric characters and other symbols can be keyed in by the operator. Keybuttons 8 can typically be arranged as in a normal typewriter. Also provided on keyboard 1 are keybuttons 9 which are used for entering command information into the apparatus. Typically the keys 9 can be used to initiate word delete, word underscore, character deletion, to move a cursor on the display, to set up tabs, temporary l~ft and right margins, etc.
As indicated above, text is displayed on the video display 2. Also displayed to assist the operator are a temporary left margin (TLM) symbol 10, a right hand margin (RHM) symbol 11, a scale 12 showing the various character positions across the display and on which tab settings B

would normally be indicated, and a cursor 13 showing the current point of interest. Shown on the display 2 is a message in which the words `'underscored" and "or" which were being entered on the third and fourth lines respectively (thereby causing overspill) have been deleted and displayed on the fourth and fifth lines respectively: this operation of word overspill will be described in detail below.
Those familiar with the IBM (Registered Trade Mark) 3277 video display unit will recall that up to 1,920 characters can be displayed in 24 rows each containing up to 80 character positions. Each row of characters on the screen is constituted by g raster scan lines, with each character being formed using, effectively a 7 x 9 dot matrix. It will be appreciated that although the preferred e~odiment is described in terms of such an arrangement, other arrangements are also possible.
All that i6 necessary is that some message buffer containing the characters to be displayed is cyclically scanned.
Referring now to Figure 2, data to be displayed are received on line 4 together with command information. The data are deserialized in interface unit 15 before being passed along line 17 to decoders 16 whose functions will be described in more detail later. Characters to be displayed are sent on line 18 to a message buffer 19 formed from cyclic shift reg- -isters and which has 1,920 character positions. The message buffer is cyclically scanned and a line (row) of characters constituting a line of text is assembled in line buffer 20 containing 80 character positions. Thus line buffer 20 will contain successive llnes of data to be displayed on the video display. Before this data can be displayed however, they must be decoded into video information and to this end line buffer 20 accesses a character generator 21 in the form of %

a read only store. Video information from the Read Only Store 21 is passed to the video display along line 22. A
buffer address register 23 contains the address on the screen of the current character of interest. Register 23 is divided into two parts, a first part 23A containing the character count identifying the position of the character within a row on the screen and a second part 23~ containing the row count indicating the row on the screen. In the example under discussion, part 23A is a 7 stage register and part 23B is a 5 stage register. A parking register 24 is used, as will be described in more detail below, during insert and delete operations. The data stream from the message buffer 19 on line 25 is rewritten into the buffer 19 through an OR gate 26, being delayed in parking register 24 under the control of control logic 27 as necessary when editing operations are being performed.
Interface unit 15 also allows the keyboard 1 to commun-icate with the decoders 16 or with the controller along line 4. The apparatus so far described with reference to Figure 2 will be recognized by those familiar with the IBM (Registered Trade Mark) 3277 video display unit as standard. The dif-ferences and modifications necessary to practice the present invention will now be described.
Characters in the data stream can be divided into three categories, text characters which are to be displayed, formatting characters which delimit a word, for example "spaces" and "required carrier returns", and other formatting characters which are not classed in this e~odiment as wGrd delimiters" formatting characters may or may not be displayed.
A "space" is a formatting character which normally separates words. "Required carrier returnH is a formatting character which is used to force the end of a line of text even though .%

there may be enough room for more words on that line: it may be displayed to provide operator assistance during editing functions. A "null" is a formatting character which is distinguishable from a l'space" in that it represents a charac-ter position on the screen which can be over-written with another character without causing shifting of subsequent characters to the right. A "temporary left margin" (TLM) character is used to specify the temporary left margin: it is displayed during text editing to provide operator assistance.
Other formatting characters, not described in this specific-ation since they are not required for an understanding thereof, include "new paragraph space" (NPS), "tab", "new paragraph tab" (NPT) and attribute characters for protect/non-protect and display/non-display. A word is normally defined as a string of text characters having one or more delimiters preceding and following it. However non-delimiting formatting characters are treated as a one-character word without the need for a delimiter to preceed or succeed it.
Within the interface 15 and decoders 16, characters are coded as 13-bit bytes as shcwn in Figure 3. This is true of characters to be displayed, formatting characters and other commands from the controller. Characters within the message buffer 19, on the other hand, are coded as 8-bit bytes as shown in Figure 4. The eighth bit of each byte is used to indicate ~hether the character is underscored. If this eighth bit is set, the character is caused to address a different section of the character generator 21 to obtain the underscored version of the character to be displayed. As an alternative, circuits, not shown, could be caused to generate an underscore and to feed this to the screen with the bit stream forming the character. This is represented by line 42 in Figure 2~
An essential feature of the invention is a word boundary counter (WBC~ 31 which keeps track of words in the data stream.
When a delimiter (space or RCR~ is decoded, a latch 32 is set to prime WBC 31. On the next text character, the row and character counts in register 23 are loaded in parallel on lines 33 and 34 into sections 31A and 31B respectively of WBC 31 so that the contents of WBC 31 always point to the start of words in the data stream. (It will be appreciated that it is a matter of choice whether the WBC 31 points to the first character of a word or the character positisn immediately preceding the first character). When a non-delimiting formatting character is decoded (defined above as a one character word), the WBC 31 is loaded with the values Of the row and character counters 23A and 23B. During each scan of the message buffer 19, the word boundary counter 31 will normally point in turn to the start of each word in the data stream appearing on line 25. As will be explained in more detail below, when a word operation such as word overspill, word delete or word underscore is executed, the normal loading of the WBC 31 is inhibited and its contents are frozen: section 35A of the WBC 31 may then be stepped as a normal counter by means of line 32 from control logic 27 until processing of that word is complete.
A hold control 41 is used to inhibit setting of latch 32 by line 43 thereby freezing WBC 31 during a word overflow operation, word dele~e operation or word underscore operation:
a signal appears on line 43 whenever decoder 28 detects a delimiting character.
A character decoder 28 examines the data stream on line 25 from message buffer 19. If a temporary left margin (TLM) character is recognized, the address of the temporary left margin is set in TLM register 22, Decoded signals from decoder 28 are also passed on line 30 to control logic 27, The TLM register 29 is set when a TLM character is entered by the operator into the position where the TLM is to start or when a TLM character is detected during the buffer scan. The TLM is terminated by a RCR character.
Right Hand Margin (RHM) register 36 contains the address of the right hand margin. In this embodiment, in the absence of any specific command, it will be the right hand edge of the display area. The value in the register 36 can be set either by a command from the controller or under operator control from the keyboard 1. Characters - entered to the right of the right hand margin must be nulls, otherwise they will be shifted to the next line.
Compaxators 37, 38 and 39 allow the comparison of the contents of the word boundary counter 31 with the buffer address register 23, the column or character count in the buffer address register 23 with the RHM register 36, and the column or-character count in the WBC 31 with the RHM register 36 respectively. The buffer address register 23 ccntains the address of each character of interest in turn within buffer 19 so that comparator 37 indicates to the control logic 23 whenever scan of the buffer 19 has reached the start of ~5 a word. Comparator 38 indicates to the control logic 23 when the buffer scan is at the right hand margin and com-parator 39 indicates when the first character of the word is at the right hand margin. Comparator 40 compares the value contained within the TLM register 29 with the character count in register 23: in other words comparator 40 indicates when the character count is at the left hand margin.

~, The operation of the apparatus ~ill now b.e descrihed in more detail. Assume that the rideo screen is completely blank and that the operator wishes to "type" a document.
The right margin can be set either from the controller or from the keyboard. When the right margin command is received in the decoder 16, the RHM register 36 will be loaded with an 8 bit byte defining the column position of the right hand ' ~.

UK9-77-004 -9a-X

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-' 1 margin.
The left hand margin will either be set by the con-troller or by the operator. Assume that a temporary left margin is to be set by the operator and to this end a left hand margin key is operated with the cursor in the required position on the screen. This causes the TLM character to enter the message buffer 19: when it is scanned and decoded by decoder 28, its position will be entered into TLM
register 29.
All other character positions will be filled with "nulls".
- The cursor will be located at the top line to the immediate right of the left margin. Using appropriate keys on the keyboard 1, the operator can enter desired text and format-ting information into the apparatus.
Figure 5 illustrates the use of the temporary left margin. Text characters and spaces 47, shown circled to indicate that they are not visible on the screen, have been entered on to the first line. It is desired to indent the second to fourth lines and to this end the operator moves the cursor into column "05'~ and then uses a "temporary left margin" key on keyboard 1. The TLM address will be entered into register 29 from character counter 23A and a TLM
symbol 46 is displayed on the screen. It will be appreci-ated that during key-stroking, the message buffer 19 is being continually scanned. Character positions before the TLM 46 are filled with nulls 48 shown circled because they are not displayed on the screen. Text is entered on the second line of the displayed text. When text is entered on the third line, the value in TLM register 29 ensures that the first text character is placed in column "05", that is the temporary left margin. A similar process happens on the fourth line of displayed text except that the 1 operator decides to terminate the temporary left margin. To this end a required carrier return (RCR) key is operated when the cursor is positioned in column "12". As a result the 4 RCR character UK9-77-004 lOa B

\

44 is displayed and the contents of TLM register 29 are erased. Thus on the fifth line of text, the first text character will be displayed in column "01".
The temporary left margin can also be used for indent-ing paragraphs. Thus the first eight characters entered in the sixth line of displayed text can represent the heading of a paragraph. The TLM key is operated with the cursor in column "09" and then text is entered. As will be seen, text entered on the seventh and eighth lines of displayed text 10 will be indented with columns "01" to "08" being filled with nulls 48. To terminate the TLM, the RCR key is operated with the cursor in column "15". Text entered on the ninth line begins at column "01". In Figure 5, the cursor 45 is shown in column "04" indicating the position of the next character (whether text or formatting) to be entered.
When the text shown in Figure 5 is printed out, the characters on the second and sixth lines to the right of the TLM character 46 will all be shifted one position to -~
the left. This compensates for the TLM character which is ; 20 displayed but not printed.
Each time that a TLM character is encountered during a message buffer scan, its address will be entered into the TLM register 29 via character decoder 28. Comparator 40 compares the TLM register 29 with the character count in buffer address register 23 to control the time that an overflow character from the hold register 24 should be inserted into the new line.
The operation of word overspill will now be described with reference to Figure 6. In Figure 6, the words "WORD
30 SPILL" are being entered at the end of a line. The - operator enters the characters W,O,R,D, space (symbol 47 circled to show it is invisible) S,P,I,L and L in that order .~

1 but makes no attempt to enter a "carriage return". As shown 2 in Figure ; .

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UK9-77-004 lla . . .

6A, the right margin is set at column "8Q"~ When the "space"
character 47 in column "73'` is decoded by character decoder 28 during the scan of the message buffer 19 next following its entry, the word boundary counter 31 will be primed by 5 means of latch 32 and when the character "W" is decoded, the contents of register 23 will be entered into counter 31 ie column 74. When the next space character 47 in column "78"
is decoded, the counter 31 is again primed and the start of the next word, character S in column "79", is entered. Normally 10 the counter is set whenever a delimiting character is scanned from the message buffer. However when comparator 38 indicates -~
to the control logic 27 that the right hand margin, column 80, is occupied by the character "P", the contents of the word ~oundary counter 31 are frozen by a signal from the control 15 logic 27 to the hold control 41 and will not be set to the address of the next word until the word overspill operation is complete. During the next scan of the message buffer 19, a "null" character 48, Figure 63, will be entered into column 79 by the control logic 27. The contents of counter 31 are 20 incremented by 1 on line 35 to give the new start of the word.
Thus the character "S" which previously occupied column "79"
will now occupy column "80". This condition is shown in Figure 6B which also shows the start of the next line. In this next line, "null" characters 48 (shown circled to indicate 25 that they are invisible) are shown in columns "01" and "02".
(The TLM character 46 is shown in column "02" of the previous line). During the next scan of message buffer 19, a null will be inserted before the start of the word, the counter -31 will be incremented by 1, and the remainder of the line 30 shifted by one position to the right. This process will be repeated until comparator 39 detects that the right hand X

.
:,. - - .. , - . .

margin, column "80" is occupied by the start of the word:
this allows the process of overspill to be completed at the next scan when normal operation of the word boundary counter 31 will continue. As characters are shifted from the end of the line, they will appear in the first vacant position on the next line. This is ensured by placing the shifted character in parking register 24 and placing it in the data stream after the temporary left margin character has been decoded. The completed operation is shown in Figure 6C. What has been described is the operation of word overspill when a document is being created. An essentially similar operation will occur when displayed text is being edited.
If a word or character is inserted, this can cause word overspill on the same line of text and possibly subsequent lines. In this event, the word overspill condition, ie the presence of a character other than a null at the right hand margin (set to column 80 in this case), would be detected by the comparator 38 during scanning of the message buffer l9, the current contents of the word boundary counter would be frozen by hold control 41, and nulls would be inserted into the data stream.
It will be appreciated that scanning of the buffer 19 occurs at a much higher rate than the operator keying rate.
Therefore there is normally no need to buffer the keyboard~
however if certain of the keys are typamatic in operation, ie continued depression causes multiple entry of the corresponding characters, a buffer may be provided in the interface 15 to avoid any possibility of lost characters due to the time taken to execute word overflows. (Typamatic operations are typically approximately 10 characters per second and the normal scan speed of the message buffer is approximately 2Q milliseconds]. When a word operation is in progress with the contents of the word boundary counter 31 frozen, fast scanning of the buffer 19 can be initiated with each scan taking approximately 2 milliseconds. During fast scanning, it may be desirable to blank the screen by means of a signal on line 49 to prevent degradation of the picture or changes from distracting the operator. When the word operation is complete, normal scanning of the buffer 19 can `-; be resumed.
Another word operation which can be performed on the apparatus of Figure 2 is word delete. The operator can key in a request for word delete by using the appropriate key on keyboard 1. The cursor can be at any position within the word. When the word delete request is decoded, the word lS boundary counter 31 is frozen at the start of the word when the cursor is decoded during the next scan of the buffer 19.
Each character in the word so specified will be deleted from the message buffer and screen, one character being deleted - ~ for each scan. The word counter 31 is incremented by 1 for each character deleted. As each character is deleted, the row of characters shifts to the left, the cursor remaining stationary. The word delete mode is reset and the counter 31 released to operate normally when the start of the next ~ word is detected. Continued (typamatic) operation of the - 25 word delete key will cause deletion of the next word or words to the e~d of the line. As an alternative, deletion can be commenced from the cursor position to the end of the word: those skilled in the art will appreciate that only a minor modification to the apparatus descxibed will be required.
~; As mentioned above, underscore is achieved by adding a bit to each character code in the message buffer 19. The .

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operator can call for word underscore by using the appropriate key on the keyboard 1, The word to be underscored is defined by the position of the cursor on the screen which may be at any position in the word or at a delimiter of the word or a null following the word. When the cursor is detected in the data stream from message buffer 19 by decoder 28, the contents of the word boundary counter 31 are frozen. If the cursor is at the start of the word, a condition recognized by comparator 37, then underscore begins immediately with the control logic 27 causing the underscore bit to be added to each data character in the word. Underscore will be completed in one scan of the message buffer 19. If the cursor is not at the start of the word, the contents of the counter 31 are frozen when the cursor is detected by decoder 28 and is held for the next cycle of the data stream. One under-score bit is added to each character as it is scanned from the message buffer 19: the contents of the counter 31 are incremented by 1 for each character and underscoring is com-plete when the first delimiter or non-data character is detected by the character decoder 28. When the value in counter 31 is equal to the character and row counts in register 23, the start of the word has been reached and insertion of the underscore bit commences and continues as ~ -described previously. In this manner, the operator can key in a word of text and then underscore it without having to reposition the cursor to the start of the word and then move it on to key in the next word. If word underscore is called and the cursor is at a formatting character, only that one formatting character (defined above as a one character word) will be underscored.
Those skilled in the art will appreciate that many . .
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modifications to the apparatus described can be made. Thus although mention has been made of the use of particular keys for use during the word delete and underscore operations~
the decoders 16 are easily able to be designed to recognize particular combinations of keys operated at the keyboard to signify a re~uest for those operations. The apparatus has also been described in relation to the entry and display of text read from left to right. It will be apparent that the invention also has application to those scripts, for example Hebrew and Arabic, which are read from right to left. In these cases word overflow would occur at the left hand margin. Similarly the invention can be used in text processing apparatus in which text is read from top - to bottom.

Claims (9)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. Text processing apparatus comprising a keyboard for entering text and command information, a video display for displaying text, a message buffer for containing text to be displayed, means for detecting the presence of a word delimiting character during cyclic scanning of said buffer to determine the start of a word in said buffer, a word boundary counter adapted to be loaded in succession with the address on the display of each word of text as said buffer is scanned, and means for preventing loading of said counter with the address of subsequent words when a processing operation is to be performed on a word and for allowing loading of said counter with the address of a subsequent word when said processing operation is completed.

2. Apparatus as claimed in claim 1, further com-prising a buffer address register adapted to contain in succession the address of each character within said buffer, and means for loading the contents of said register into said counter when a delimiting character defining a word is detected by said detection means.

3. Apparatus as claimed in claim 2 comprising word overspill detection logic for detecting when a text charac-ter is entered beyond a margin on the display and for causing operation of said loading prevention means, means for deleting text characters from the word currently in-dicated by said word boundary counter and for inserting said deleted characters on the next line of text.

4. Apparatus as claimed in claim 3, in which said word overspill logic includes comparison means for comparing the address of a character entered for display with the contents of a terminal margin register containing the address of the current terminal margin.

5. Apparatus as claimed in claim 4, comprising means operable during each scan of said buffer to increment said counter by 1 and to insert a null character before said word causing overspill, and means for detecting when the con-tent of said counter is equal to the content of said terminal margin register.

6. Apparatus as claimed in claim 5 comprising means responsive to a word delete command entered on the keyboard for causing operation of said loading prevention means and for deleting characters in the word indicated by the con-tents of said counter until the start of the next word is detected.

7. Apparatus as claimed in claim 6 comprising means responsive to a word underscore command entered on said keyboard for causing operation of said loading prevention means and for underscoring characters in the word indicated by the contents of said counter until the start of the next word is detected.

8. Apparatus as claimed in claim 7, comprising means for detecting when the buffer scan reaches the beginning of the word whose address is held in said counter, means for initiating said delete or underscore operation on the first character of the word, means for incrementing the counter by 1 for each character deleted or underscored during scanning of the buffer, and means for terminating said delete or underscore operation when the count in the counter is equal to the address of a delimiting character indicating the start of the next word.

9. Apparatus as claimed in claim 8 comprising means for inhibiting display of text on said display whilst load-ing of said counter is prevented.