US3750135A

US3750135A - Low resolution graphics for crt displays

Info

Publication number: US3750135A
Application number: US00189496A
Authority: US
Inventors: P Carey; O Holmwood
Original assignee: LEKTROMEDIA Ltd
Current assignee: LEKTROMEDIA Ltd
Priority date: 1971-10-15
Filing date: 1971-10-15
Publication date: 1973-07-31
Anticipated expiration: 1990-07-31

Abstract

A system for generating and displaying graphical information for interactive computer display terminals using graphic display mediums employing a raster pattern, such as a cathode ray tube. The system uses programmable character elements for constructing graphic characters in such manner that they are highly adaptable for display by conventional television monitors. Each graphic character is constructed by the character elements in an individual cell pattern and a plurality of these adjacently located cell patterns render a continuous graphic diagram. All of the cells which make up the graphic diagram are of the same size and typically eight dots by twelve dots and a plurality of graphic element or font types may be used in these cells to generate the various graphic characters. One form of traphic element cell pattern generates the graphic characters in individual cells by means of a plural-point pattern and preferably a six-point pattern and in another form the graphic elements generates the graphic character by means of a plural-bar pattern and preferably a four-bar pattern. The system includes a mimic style keyboard along with cursor controls which are used to create the continuous graphic diagram. An eight bit word representing each character is loaded into a buffer or scanned storage and after a complete diagram has been composed a page representing this diagram may then be loaded into a permanent storage. The system is operable in an origination mode, a storage mode, a presentation mode and a modification mode. A unique programmable read-only memory and associated logic including a unique gating structure permits the display of alpha-numeric data generated at an alpha-numeric keyboard, along with the display of the above mentioned graphic character patterns.

Description

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Quebec, Canada 22 Filed: Oct. 15, 197i 211 Appl. No.: 189,496

[52] US. Cl. 340/324 AD, l78/DIG. 22, l78/DllG. 35

Primary ExaminerDavid L. Trafton AttorneyRobert J. Schaap [57] ABSTRACT A system for generating and displaying graphical information for interactive computer display terminals using graphic display mediums employing a raster pattern, such as a cathode ray tube. The system uses programmable character elements for constructing graphic characters in such manner that they are highly adaptable for display by conventional television monitors. Each graphic character is constructed by the character elements in an individual cell pattern and a plurality of these adjacently located cell patterns render a continuous graphic diagram. All of the cells which make up the graphic diagram are of the same size and typically eight dots by twelve dots and a plurality of graphic element or font types may be used in these cells to generate the various graphic characters. ()ne form of traphic element cell pattern generates the graphic characters in individual cells by means of a plural-point pattern and preferably a six-point pattern and in another form the graphic elements generates the graphic character by means of a plural-bar pattern and preferably a four-bar pattern. The system includes a mimic style keyboard along with cursor controls which are used to create the continuous graphic diagram. An eight bit word representing each character is loaded into a buffer or scanned storage and after a complete diagram has been composed a page representing this diagram may then be loaded into a permanent storage. The system is operable in an origination mode, a storage mode, a presentation mode and a modification mode. A unique programmable read-only memory and associated logic including a unique gating structure permits the display of alpha-numeric data generated at an alpha-numeric keyboard, along with the display of the above mentioned graphic character patterns.

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LOW RESOLUTION GRAPHICS FOR CRT DISPLAYS BACKGROUND OF THE INVENTION This invention relates in general to certain new and useful improvements in the generation and display of information for interactive computer display terminals, and more particularly, to the generation and display of such information on graphic display mediums which employ a raster pattern.

In recent years various systems relating to the generation and displaying of graphical information for interactive computer display terminals has been receiving increased prominence. There have been a number of techniques developed for the display of information stored in computer memory and information which is introduced externally through an operator, such as by means of a keyboard entry device. This data which may include alpha-numeric information and/or other graphical information is then generated and depicted on a display screen through an electron beam under computer control.

Increased prominence in the use of computer interactive terminal displays has resulted in large part from the high degree of effectiveness achieved by pictorially displaying objects, oftentimes along with alphanumeric data, for a wide variety of purposes. In many cases, pictorial displays are used for the shaping or designing of computer control machine parts, the production of intricate high resolution photographic masks or the like. Computer interactive terminal displays are also used in the solving of pictorial problems such as highway planning, topographical mapping and other problems which are readily solved through visual examination of a physical phenomena.

Computer interactive terminal displays are also used in gaining insight into complex natural or mathematical phenomena through a simulation of various types of physical situations in a computer with attendant display devices to present the results of the simulation. For example, an organic chemist desiring to synthesize a particular molecule creates a picture of the molecule on the display screen and then initiates a program by which the computer presents a selection of simpler molecules from which the desired substance can be synthesized. In like manner, these graphic displays are also used in the study of blood flow, the study of elementary particle interaction in electric fields and determination of polls and zeros on a complex plane, etc.

In more recent times, computer displays employing cathode ray tube display mechanisms have been used for educational purposes such as in the training of pilots through simulating pilot practice take-offs and landings and in other operations where an individual may learn to control a manually operable mechanism through simulation training. Widespread use has also been made of closed-circuit television systems for the displaying of lectures, along with pictorial illustrations of information written on blackboards and the like.

Twobroad classes of computer display systems are now in common use, namely the calligraphic display and the raster pattern displays. These systems are designed to reproduce and display graphical symbology and pictures or parts thereof along with alpha-numeric data through computer interactive display terminals in any sequence transmitted by a computer. In the calligraphic display an electron beam moves from place to place in a pattern that traces out the individual lines and characters which make up the picture. The calligraphic display system is advantageous in that the information to be displayed can be stored in the computer memory in essentially any order. The raster pattern display generates a pictorial image in essentially the same manner as the conventional television monitor, but the information for raster display must be sorted from top to bottom and left to right so that it can be placed on the screen in correct sequence. Notwithstanding, the electronic sophistication of the calligraphic display requires rather complex deflection amplifiers, deflection yokes and other complex related components which render the system materially more complex and accordingly this type of system carries a considerably higher purchase or lease cost.

One of the common graphic display systems which uses a calligraphic pattern involves the presentation of a diagram or character by means of a series of interconnecting lines, or strokes with coordinate positions supplied by stored information in the computer. The computer memory associated with the presentation of displays of this type only stores the coordinates of each end of the line in order to describe the full length of the line. Such a display system, however, requires a cathode ray tube unit that can be randomly scanned and hence this type of display is not compatible with standard television signals.

One of the primary methods employed for displaying graphic diagrams or characters when using conventional television monitors involves the construction of a diagram on a point-by-point basis using a matrix of dot elements which may be individually controlled. In this method, a sequential scanning action compatible with standard television techniques is employed thereby permitting the use of standard television monitors. However, in order to describe a character such as a line with this technique, it is necessary to store every individual point along the line in order to reconstruct the line on the screen. Therefore, this system requires an extremely large memory unit.

There have been several attempts to obviate the problem of displaying both alpha-numeric characters and graphic characters on a cathode ray tube screen with a raster pattern, but these attempts have not been particularly effective when a standard television monitor was employed. Usually that equipment which is commercially available involves a substantial purchase or lease cost and generally requires skilled operators. In addition, many of these systems do not have write capabilities which materially limits the effectiveness of the display system.

GENERAL DESCRIPTION The present invention, therefore, provides a system which is capable of originating, storing, presenting and modifying graphical information and presenting this graphical information in combination with alphanumeric information for interactive computer display terminals. This system is uniquely designed so that the same transmission and processing equipment used for simple alpha-numeric information displays can be utilized. Furthermore, the system of the present invention is highly effective in that it can be used for the display of this alpha-numeric and graphical information on a conventional television monitor raster screen, without the necessity of expensive and highly complicated attendant or auxiliary equipment in order to accomplish this purpose. The system of the present invention is also highly effective in that it can be operated by relatively unskilled personnel requiring only a minimum degree of training and further, the original purchase or lease cost, operating cost and maintenance cost of this subject system is considerably lower when compared to other commercially available systems.

The present invention includes both a system and a method for generating graphic displays; and more particularly, the invention is described as a system and a method for generating graphic displays on the screen of a monitor operable with a raster pattern. In general terms, the system comprises first pattern forming means for generating a first type of character elements combinable to form a graphic character, first switch means operatively associated with the first pattern forming means to select certain of the first type of character elements in a desired arrangement and combined to form a first graphic character in a raster location. The system also comprises second pattern forming means for generating a second type of character elements combinable to form a graphic character, second switch means operatively associated with the second pattern forming means to select certain of the second type of character elements in a desired arrangement and combined to form a second graphic character in another raster location. Finally, the system comprises cursor means to position the various graphic characters formed from said types of character elements in a desired arrangement to form a graphic display.

The method of the present invention could be described in general terms as a method for generating graphic-type displays on the screen of a monitor operable with a raster as aforesaid, and where the method comprises establishing a plurality of raster locations of predetermined font size on a screen associated with the monitor, generating a first type of character elements combinable to form graphic characters of predetermined font size in certain of said raster locations, generating a second type of graphic character elements which are distinct from said first type of character elements and combinable to form graphic characters of said predetermined font size in certain other of said raster locations. Finally, the method includes positioning the graphic characters formed in said raster locations in a desired arrangement to form a graphic display.

The system for generating the graphic displays more specifically can be characterized in that the first pattern forming means generates bar-type character elements and preferably, four-bar character elements, and further, that the second pattern forming means generates point-like character elements and preferably sixpoint character elements. In this manner, a maximum of four of such bar-type elements constitutes a graphic character in any one raster location and that a maximum of six of the point-type elements constitutes a graphic character in any other raster location. In a preferred embodiment, the system of the present invention includes means for adding alpha-numeric characters to the graphic displays in order to generate a composite informational display of graphic characters and alphanumeric characters.

The present invention can also be described in general terms as a display system for interactive computer display terminals and where the system comprises a first input means capable of generating a multi-bit binary graphic word, and second input means capable of generating a multi-bit binary alpha-numeric data word. The system also further comprises first storage means operatively associated with the first input means to receive certain bits of the multi-bit graphic word, and second storage means operatively associated with the second input means to receive certain bits of said multibit alpha-numeric word. The display system also comprises selector means operatively connected to said first and second storage means to select between alphanumeric data words and graphic words. Finally, the system includes clocking means for clocking either the graphic word or the alpha-numeric data word to the monitor to display the characters defined by the words.

The display system for the interactive computer display terminals of the type mentioned above, can be further characterized in that a main register is connected to the selector means to receive either the graphic or the alpha-numeric data word which is selected by the selector means. In addition, the system includes a clocking means which is operable with the main register to generate a video-signal from the word received in the main register. Further, a mixer may be provided for receiving the video-signal and a television type input signal to form a signal complex therefrom for display through the interactive computer display terminals. The display system for these interactive computer display terminals is a monitor having a screen operable by a raster pattern and more specifically a television monitor.

In a preferred embodiment, the clocking means is a column counter for determining a particular column in any raster location and that row counter means is provided and operatively associated with the first and second storage means for determining the row location in any of the columns in this raster location. The first storage means and the second storage means are read-only memories and preferably, programmable read-only memories. In addition, a first gating circuit may be interposed between the first and second storage means and the selector means and a second gating circuit may be interposed between the second storage means and the selector means. The first input means is a graphictype keyboard comprising first switch-type means for generating plural-bar character elements and second switch-type means for generating plural-point character elements. The second input means is an alphanumeric-type keyboard capable of generating both arabic and numeric and other forms of characters.

The present invention can also be described in general terms as a circuit active means for determining coordinate positions of character elements in a raster location on a display screen and where the character elements are combinable in a desired arrangement to form the desired characters. This circuit active means comprises a first storage member receiving a multi-bit word defining the character elements and representing a character comprised of these character elements, a gating matrix for receiving certain of the bits of said multibit word defining the character elements, a second storage member receiving another bit from the multi-bit word characterizing the type of character elements. The circuit active means further comprises first location counter means operatively connected to the second storage member and generating signals representing a first coordinate axis location for these elements. These signals are introducable into the gating matrix for gating certain of the bits representing certain of the character elements from the gating matrix. Finally, the circuit active means includes second location counter means operable with the certain gated bits to determine a second coordinate axis location, to thereby define the coordinate positions of the character elements in the raster location.

In more specific terms, the circuit active means can be characterized in that the first storage member is a buffer memory, the second storage member is a gating matrix and the third storage member is a read-only memory unit, and preferably a programmable readonly memory. In addition, the circuit active means can be further characterized in that a plurality of different types of character elements can be used to generate the graphic characters and that the bit introduced into the second storage member represents the type of character elements introduced into the gating matrix. The different types of character elements which are used to generate the different characters include in one form a series of bar-like elements and in another form, a series of point-like elements, and that the bit of a multi-bit word which is introduced into the second storage member characterizes between the point-like elements and the bar-like elements.

In other general terms, the present invention can also be described as a data output circuit for gating certain bits of a multi-bit word in response to a plurality of input signals and where certain of the bits in the multibit word represent a first type of elements and certain of the bits in the muIti-bit word represent a second type of elements. Further, the multi-bit word includes a characterization bit which distinguishes between the said two types of elements. The data output circuit comprises a plurality of gating members for receiving certain of the bits of the multi-bit word, signal generating means receiving the characterization bit and first clocking means for generating first clocking signals and introducing these clock signals into the signal generating means. The data output circuit further includes the fact that signal generating means generates a plurality of input signals in response to these clock signals and introduces the input signals into the gating members to thereby gate certain of the bits in response to certain of the input signals. The circuit further includes register means for receiving the gated bits and clocking means for introducing clocking signals into the register means to thereby transmit these gated bits on a serial basis.

In more detail, the signal generating means of the data output circuit described above is a read-only memory unit and this read-only memory unit comprises a decoding matrix and a word select matrix. The gating members are preferably a series of NAND gates present in a number at least equivalent to the number of bits in the multi-bit word representing the second type of elements. The input signals to the gating members are signals which designate a first coordinate location position and the clocking signals which are generated by the second clocking means are signals which designate another coordinate location position.

In a preferred embodiment, the present invention provides a unique means of generating a plurality of font patterns on the screen of a monitor to produce graphic characters and these graphic characters are formed from different types of character forming elements. The monitor is preferably of the type which uses an electron beam raster to control a series of dots on the screen surface, such as a television display screen. The screen is made up of a plurality of columns and rows or lines which form a plurality of raster locations and each raster location is formed of a plurality of the dots and preferably with an aspect ratio of 3:2. Typically, each raster location will contain an eight by twelve dot structure.

The first of these font patterns is made up of pluralbar character elements and preferably a four-bar font pattern where a maximum of four bars can exist in a desired orientation in any font or raster location. The second of these font patterns is made up of plural-point character elements and preferably a six-point font pattern where a maximum of six points can exist in a desired orientation in a font or raster location. The graphic characters are made up of these graphic elements, and a group of raster locations in combination, each having a graphic character displayed therein form a graphic display.

The graphic characters are generated by means of a first input means in the form of a graphic keyboard which contains a first set of keys capable of generating the plural-bar pattern and a second set of keys generating the plural-point pattern. Other forms of input means which employ different types of input switches or the like could be used as well. Furthermore, it is also possible to use signal inputs in place of manually actuated inputs such as keys or switches in order to generate the desired graphic characters.

In order to provide a total informational display, alpha-numeric or other forms of characters can be visually depicted on the screen of the monitor along with the graphic characters. For this purpose an alpha numeric keyboard or other input mechanism is employed. The alpha-numeric keyboard preferably contains a first set of input switches such as numeric keys and a second set of input switches such as arabic keys and possibly other non-descript input switches or keys. Again, it is possible to use other input forms which are not manually operable as described in connection with the graphic keyboard mentioned above. One entire graphic display constitutes one page which can be permanently stored in a computer memory or the like. In the display of any page, the characters which are introduced from the input means and the data words in the computer memory are introduced into a scanning memory. Thereafter, these data words and the other character information introduced into the scanning memory are processed for visual display on the screen of the monitor.

A system is provided for generating the graphic and alpha-numeric display from the information introduced into the scanned storage. These characters are introduced into a first memory or buffer memory in the form of a plural bit word and preferably an eight bit word. The graphic characters are preferably formed from eight bit digital codes and the alpha-numeric characters may also be formed of this eight bit digital code, or other codes as desired.

The first four least significant bits in this eight bit data word are used to represent the plural-bar characters and these first four least significant bits plus the next two least significant additional bits of this eight bit data word are used to represent the six-point characters. The seventh bit distinguishes between the pluralpoint character elements and the plural-bar character elements and the eighth bit distinguishes between the graphic characters and the alpha-numeric characters.

A second storage member such as a read-only memory and preferably a programmable read-only memory receives the seventh bit from the buffer memory. In addition, the read-only memory receives multiple row count inputs and preferably four row count inputs from a row counter and is capable of generating output location coordinate signals. The read-only memory is desirably formed ofa decoding matrix and a word select matrix, the latter of which receives the row count signals from the row counter. The output of the decoding matrix is passed through a series of buffers to generate the output signals which are introduced into a gating circuit. The combination of the gating circuit and readonly memory form a graphic character generator. This gating circuit receives the first six bits of any word introduced into the buffer memory and also receives the location signals from the read-only memory as aforesaid. The gating circuit is preferably formed of a series of NAND gates which are operable by the six bits and the location coordinate signals from the read-only memory. The alpha-numeric character generator is also comprised ofa read-only memory and a gating matrix and operates in a similar manner.

The eight bits of the multi-bit word contained in the buffer memory is introduced into a selector mechanism and this selector mechanism receives the output of the gating circuit, as well as the alpha-numeric input. When the eight bit is true, the word which is gated from the gating circuit represents a graphic character and when the eighth bit is not true, the word which is introduced into the selector is an alpha-numeric data word. The output of the selector which contains eight bits is introduced in parallel arrangement into a main register which also receives eight clock signals from a column counter and these eight clock signals essentially represent a second set oflocation coordinates for each of the bits in the eight bit word introduced into the main register. The output of the main register is introduced into a mixer and combined with a television input to provide a video-television signal complex. This signal complex is then introduced into the monitor for display.

Having thus generally described the invention, reference will now be made to the accompanying drawings which illustrate a preferred embodiment of the present invention and in which:

FIG. I is a schematic view showing the geometric construction of both graphical characters and alphanumeric Characters on a display scre FIG. 2a is a diagramatic view showing the dot structure in one raster location on a screen and the generation of a graphical character using a six-point pattern;

FIG. 2b is a schematic view showing the data bit positions for each point in the raster location in order to achieve the graphic character pattern illustrated in FIG. 2a;

FIG. 3a is a diagramatic view showing the dot structure in one raster location on a screen and the generation of a graphical character using a four-line pattern;

FIG. 3b is a schematic view showing the data bit positions for each line in the raster location in order to achieve the graphic character pattern illustrated in FIG. 3a;

FIG. 4 is a schematic view of a system for displaying and storing graphical characters 7 along with alphanumeric characters on a television raster monitor (appearing on sheet 2);

FIG. 5 is a schematic view of the circuitry of a programmable read only memory included in the system illustrated in FIG. 4 (appearing on sheet 1);

FIG. 6 is a gating structure used in the generation of a plural-bar pattern and forming part of a gating circuit included in the system of FIG. 4;

FIG. 7 is a schematic view of a gating structure used in the generation of a plural-point pattern and forming part of the gating circuit included in the system of FIG. 4; and

FIG. 8 is a schematic view of a combination of the gating structures of FIGS. 6 and 7 to form the gating circuit.

DETAILED DESCRIPTION Referring now in more detail and by reference characters to the drawings which illustrate a preferred embodiment of the present invention, FIG. 1 illustrates a display screen operable with a raster pattern, such as a standard television display screen. The screen used for the purpose of describing the present invention will contain 32 vertically extending columns which represents a total of 32 raster locations or cells per line and 16 horizontally extending rows which represents a total of 16 lines. Accordingly, a screen of this size would contain 512 raster locations or cells and hence could display a maximum of 512 graphic characters and/0r alpha-numeric characters at any point in time. One complete graphic display may or may not use all of the possible 512 raster or character locations or cells and the complete graphic display at any point in time is referred to in the art as one page.

Accordingly, a screen of the size mentioned above having five hundred twelve raster locations would permit generation of a page with a maximum number of 512 character locations. It should be recognized that the screen and, therefore, the page could be composed of any desired number of characters by altering the number of character columns and character rows or lines. Each raster location on the screen which defines one character location has been assigned a size of twelve horizontal dot rows by eight vertical dot columns or a total raster location size of 96 dots with an aspect ratio of 3:2, inasmuch as many graphic display systems using interactive computer display terminals employ this raster location size. Nevertheless, it should be understood that essentially any size raster location could be employed for the purposes of the present invention. One such raster location has been illustrated in FIG. 1 and designated with reference numeral 2. This raster location or cell 2 is materially enlarged with respect to the remainder of the figure for purposes of clarity.

While the cell size in many of the prior art graphic display systems were also assigned an eight dot by l2 dot pattern only approximately five dots by seven dots were used in the entire cell for the display of any character. Generally, the character was graphically displayed in the upper left-hand corner of the cell so that three dot columns and five dot rows were not used in these prior art cell patterns. In this manner, various alpha-numeric characters were displayed with spaces automatically existing between the lines of characters.

Referring again to FIG. 1, it can be observed that a graphic diagram may be composed of all graphic characters or alpha-numeric characters including both arabic and numeric characters. As used herein, the term graphic character represents a character other than an alpha-numeric character, and particularly a character which alone or in combination with other characters presents an illustration for visual review, rather than for reading as in the case of alpha-numeric text. Accordingly, the term graphic or graphical" could represent any type of geometric construction such as a line, whether it be curved, curvilinear or straight, lines segments, points, or the like. Generally, a graphic character would represent only a segment of a final display so that if a circle were to be portrayed, a group of graphic characters, each representing an arc, would be combined in such manner to form the circle. The term graphic display represents the presentation of graphical characters combined to form a geometric or like pattern as opposed to alpha-numeric text. The term informational display as used herein represents the presentation of either graphical characters and/or alpha-numeric characters alone, or in combination with other forms of information.

With further reference to FIG. 1, it can be observed that graphical diagrams are composed by constructing a series of adjoining graphical characters and these graphic characters are each formed by various character elements in each of the raster locations. By illuminating various of the character elements in each raster location a portion of a graphic character and hence a font pattern is generated. In a preferred embodiment of the present invention one form of font pattern is generated by a plural-point pattern and preferably a six-point pattern and, another form of font pattern is generated by a plural-bar pattern and preferably a four-bar pattern, and any of the eight dot by twelve dot raster locations may be used for the displaying of the six-point or the four-bar graphic characters. Furthermore, any of these raster locations may also be used to display the conventional numeric characters or arabic characters also in a manner to be hereinafter described.

Each graphic character is stored, processed and transmitted as an eight-bit data word and may be displayed in any of a number of discreet character or raster locations on the screen arranged in the character rows and character columns as aforesaid. The positioning of such characters, the number of characters per line and the number of character lines present is determined by the graphical display to be presented. Furthermore alpha-numeric characters may be displayed along with the graphic characters as indicated above, and the coordinates of these characters would be determined by coordinate information in the computer storage.

An eight-bit data word is used to represent the numeric characters and the arabic characters included in the alpha-numeric code, as well as the graphical characters as aforesaid. in both the graphical and the alphanumeric characters only seven of the bits of each eightbit word are used to describe the character, thereby providing 128 possible combinations. The eighth and most significant bit in each character word is a characterization bit for determining whether the accompanying seven bits represent an alpha-numeric character or a graphical character. Each eight bits which represent one word and hence one character. constitute one byte in the digital code system employed herein. However, it should be understood that other digital codes could be employed such as a four bit BCD code to represent numeric characters, a five bit code to represent any arabic or numeric character, and that the present invention is not limited to the eight bit code employed herein. Further, a byte could contain less than eight bits and a character word could be comprised of a plurality of bytes so that if a four bit code were employed, one character word could be represented by two bytes of bit information.

The font patterns or font" for the graphic characters in each raster location are more fully illustrated in F IGS. 2a and 3a; FiG. 2a showing a raster location with the plural-point pattern such as the six-point pattern and FIG. 3a showing a raster location with the pluralbar pattern such as the four-bar pattern. Each point in the six-point pattern may be controlled independently and each point comprises four dots in the raster location so that all six points in the font are represented by a total of 24 dots in the raster location. The term dot" is used in its conventional sense in that each dot represents an area of the size which is electron beam scanned at any point in time and is generally individually controllable with respect to all dots in the screen structure. The points in the plural-point pattern are substantially larger than the dots in the dot structure of the raster location so that one point essentially covers four dots in the dot structure and furthermore the points are somewhat rectangular in shape. Furthermore, each of the six points are separated by two dot spaces and are located in rectangular arrangement in the manner as illustrated in FIG. 2a. The status of each point is defined by the six least significant bits in the eight bit data word, namely bits B-l through B-6 and the seventh bit 3-7 is provided to distinguish between a six-point character and a four-bar character. Finally, the eighth bit B-8 in the character word is used to identify the graphic character word as aforesaid, the eighth bit being a logical zero for alpha-numeric characters and a logical one for graphic characters.

The four-bar pattern is more fully illustrated in FIG. 3a,- each of the bars in the four-bar pattern being represented by one binary bit in the seven-bit word and each of the four bars may be controlled independently. Each bar in the four-bar pattern is approximately two dots wide and are located in the raster location so that they assume the appearance of a cross when all bars are illuminated in the manner as illustrated in FIG. 3a. Thus, if any one of the four bars in the four-bar font pattern is illuminated, the central position of the font will be illuminated. The status of each of the bars in the fourbar pattern is defined by the four least significant bits in the eight-bit word. Again, bits B-7 and B-8 are used in the same manner as in the case of the six-point pattern, except that bits B-5 and B-6 are not used in the four-bar pattern.

The graphic patterns are produced by actuation of the keys on a keyboard (to be hereinafter described) in any desired pattern in order to achieve a desired graphic display. For example, the operator of the system could generate a linear graph having an abscissa axis designated as X-AXIS" and an ordinate axis, designated as "Y-AXIS through generation of successive straight lines by using the four-bar character fonts. in like manner, by actuating proper keys on the keyboard, the operator can generate a series of points which form a cruve 3 coordinated by the ordinate and abscissa axises mentioned above. The term X-AXIS and the term Y-AXXS could be conveniently generated through actuation of the keys on an alpha-numeric keyboard (to be hereinafter described) and suitably placed on the screen with respect to the display of the linear graph. Each font raster location is used to generate a plurality of points which only form a portion of the curve 3, and therefore it can be observed that a plurality of adjacent and continuous raster locations together will generate the entire curve 3 in the form of a low resolution dot structure. in this manner, the illustrations of the various preselected plural-points in each of the adjacent continuous raster locations will appear as one complete continuous curve due to the low resolution of the display achieved by this system.

A system S for generating the informational displays which includes the display of the graphic characters and the alphanumeric characters, as aforesaid, is more fully illustrated in FlG. 4. As indicated above, this system is operable with almost any type of computer interactive terminal display monitor employing a raster pattern; but is particularly designed for use with cathode ray tube systems, such as a conventional television monitor. One of the most preferred forms of cathode ray tube systems employs a screen with a phosphorus coating which is scanned by an electron beam. Generally a cathode in the tube will emit an electron stream through a grid and this electron stream will be focused on an accelerating anode. A pair of oppositely disposed deflection plates will enable the electron beam to in effect scan or sweep the screen.

The screen which essentially constitutes one frame is typically scanned in about one-thirtieth of a second, and preferably contains a pair of interlaced fields which form the frame and where each field is scanned in about one-sixtieth of a second. The beams in the two fields will generally scan from left to right, probably with overscanning, and will retrace in a substantially shorter period of time than the scan or sweep period. The beam will be modulated by the grid and the intensity of the light will be a function of the voltage applied to the grid. Furthermore, the beam will be deflected either electromagnetically or electrostatically, though electrostatic deflection is the preferred form.

This system S is capable of being used in essentially four basic modes of operation, namely origination, storage, presentation and modification. The origination mode is used to generate new informational displays which include graphic characters and/or alpha-numeric characters, and is generally achieved by actuation of the keyboards to be hereinafter described. After an informational display has been created on the screen of a monitor (and which display constitutes one page) this informational display or page can then be stored in a computer memory by operation of the system in the storage mode. in the presentation mode of operation, the information in the storage, such as this above mentioned page, for example, could be presented on the screen of the monitor in the manner as it was originally stored. In the modification mode of operation, the stored page would also be presented for display on the screen of the monitor, but certain modifications to the page would be performed. These modifications can be achieved by adding information to the page on display, such as alpha-numeric characters or graphic characters, or by altering or deleting some of the characters included in the page on display.

The system S for generating the informational display generally comprises a graphic keyboard and an alpha-numeric keyboard 11 in the manner as illustrated in FIG. 4, and which keyboards would normally be mounted in a suitable operators console (not shown). The alpha-numeric keyboard 11 generally includes a keyboard block 12 containing numerically labeled keys for introducing numeric characters. The keyboard 12 would normally include nine keys labeled with successive digits "1 through 9" and a tenth key labeled 0. The keyboard 11 would also contain a keyboard block 13 with 26 keys having the letters of the alphabet imprinted on the surface of these keys. As indicated above, the keyboard would contain 26 keys for the generation of arabic characters, though it should be understood that the exact number of keys would be dependent upon the particular type of alpha-numeric characters to be generated. For example, characters can conveniently be generated in the Russian Language which requires an additional number of keys and the keyboard block 13 would thus be provided with the proper number of keys. The keyboard 11 is also provided with a space bar 14 for the generation of spaces between any of the alpha-numeric characters. It should also be recognized that this keyboard 11 could be provided with additional keys having punctuation marks, such as periods, commas, asterisks, or the like, as desired.

The alpha-numeric keyboard 11 is further provided with a clear switch 15 and a load switch 16 for purposes which will be more fully defined hereinafter. All of the aforesaid switches on the keyboard 11 are preferably push button type switches which enable an energized state upon actuation and are biased to return to the deactivated position. Furthermore, these switches may all be provided with internally located lights, such as small conventional neon tubes (not shown) so that the face of the switch will be illuminated upon actuation thereof. The alpha-numeric keyboard could also be provided with display tubes such as multi-segment cold cathode display tubes (Nixi tubes) which wuld be energized upon actuation of any of the keys on the keyboard 11. Typically, a thirteen segment cold cathode tube could be energized to indicate the actuation of any particular key on the keyboard. In this manner, the operator could visually inspect the alpha-numeric information he plans to introduce into the system, prior to the actual introduction of this information into the system. Suitable anode and cathode shift registers along with a display shift register and the attendant circuitry can be provided for this purpose.

The graphic keyboard 10 is preferably a mimic style keyboard which is used to compose the graphic diagram and generally includes a plural-bar keyboard block 17 and a plural-point keyboard block 18. The plural-bar keyboard block 17 will normally contain a number of bar-keys which are equivalent to the number of bars present in any font. Since any font can be generated with any or all of the four bars in a four-bar pattern, the keyboard block 17 will contain two horizontally located keys l9 and 20 and two vertically located keys 21 and 22 in the manner as illustrated in FIG. 4. The keys 19 through 22 are all located in positions on the keyboard block 17 so that they generate a graphic display in any particular raster location in the same pattern as they appear on the keyboard block 17. Thus, acmation of the keys 19 and 20 will produce a horizontal line in the raster location. Actuation of the keys 21 and 22 will produce a vertical line in the raster location, and actuation of all four keys will produce a cross similar to that appearing on the keyboard block 17.

The keyboard block lid is also provided with a number of keys equivalent to the number of points in any font pattern or appearing in any raster location. As indicated above, each font pattern will employ a total of six points and, therefore, the keyboard block 1% is provided with six keys 23 located in the form of a rectangle, in the manner as illustrated in F l6. 4. Thus, actuation of all of the keys 23 on the keyboard block 1% will produce a font pattern which is equivalent to the an rangement of the keys 23 on the keyboard block lid.

The graphic keyboard is further provided with a load switch 23 and a clear switch 23 as well as cursor controls 26. The cursor controls 26 are of the type normally associated with cathode ray tube display systems and permits the operator of the system to properly position the graphic characters on the display screen of the monitor. When composing any of the graphic characters, the operator will normally position the cursor to locate the first graphic character. The cursor is of the type which can be moved, up, down, forward and reverse.

The output of the graphic keyboard 10 and the output of the alpha-numeric keyboard 1 .1 both serve as inputs to a scanned storage 27 which also has output and input lines to a computer storage C which is described in more detail hereinafter. The scanned storage 27 also provides an output synchronized to column counter 41. The scanned storage 27 is a storage member of conventional construction, preferably a recirculating shift register containing a series of multi-stable elements, though other forms of scanned storage members can be used in the present invention. The scanned storage 27 examines the outputs of the keyboards W and 11 for further processing in a manner to be hereinafter described. The scanned storage 27 also serves as an intermediate buffer for introducing data words into the computer storage C.

The output from the scanned storage 27 is connected to an eight-bit data word recirculating buffer memory 30. The recirculating buffer memory 30 is only schematically illustrated in block diagram form since memories of this type are commercially available and generally include a series of bi-stable elements, sufficient in number to accommodate each bit of a generated byte or word, along with recirculating controls.

As indicated previously, the first six least significant bits in the data word represent the form of the graphic character, the seventh bit determines whether the character is composed of plural bars or plural points and the eighth bit determines whether the character is a graphic character or an alpha-numeric character. Accordingly, the buffer memory 30 is provided with a bit-8 output line 33 connected to a selector 3d and which output line 33 will be energized when bit-@ is true. Accordingly, if bit-8 is in fact true, then the character generated will be a graphic character.

The buffer memory 30 has a bit B-7 output connected to a programmable read-only memory 35 forming part of a graphic character generator C and a bit B-7 output connected to a similar programmable readonly memory 35 forming part of an alpha-numeric character generator C The graphic character generator C includes a special gating circuit 36 which receives six outputs from the read-only memory 35 in a manner to be hereinafter described in more detail and this gating circuit 36 is more fully illustrated in FIGS. 6, 7 and 8 of the drawings. The output of the graphic character generator C is introduced into the selector 34 by means of a line 37 and the output of the alphanumeric character generator C is introduced into the mixer 3d by means of a line 37' which will be generated only when bit-d is not true or 0."

The programmable read-only memory 35 internally includes thirty-two locations which are addressable by five-bit address words. F our bits of these address words are derived directly from a row counter 38 which controls the eight by twelve dot raster location and specifies which of the twelve rows or lines in the raster location is being scanned at any point in time. The row counter 3% also has a four bit address word input to the read-only memory 35 and also specifies the raster location being scanned at any point in time. The fifth bit in the address word is the seventh bit in the seven-bit data word defining that a graphic character is contained in the buffer memory 30. Thus, it can be observed that the buffer memory 30 is sized to contain one complete character word and in this connection would probably include eight multi-stable elements, such as flip-flops and recirculating controls therefor.

The status of bit-7 in the data word contained in the buffer memory 30 essentially defines whether graphic characters are to be formed from the four-bar pattern or the six-point pattern. The first 16 locations in the read-only memory 35 are programmed to generate the four-bar pattern and locations 17-31 in the read-only memory 37 are used to generate the six-point pattern. The output of the read-only memory 37 which defines the pattern of the graphic character to be displayed is introduced into the special gating circuit 36.

The gating circuits 36 and 36' also receive the first six least significant bits of the data word in the buffer memory 30 and permits the gating of outputs to the selector 34 through the lines 37 and 37', respectively, in the manner as illustrated in FIG. 4i. The selector 34 is provided with eight outputs connected to a main data shift register 40 also receiving eight inputs from a column counter 41. The main data register 40 is essentially an eight location parallel input-serial output shift register. This column counter 41 specifies which of the eight columns in the font is being scanned at any point in time and operates in conjunction with the row counter 33 to determine the coordinate position of any dot in the font. The output of the main register 40 may be mixed with a television input signal in a mixer 42 and then displayed on the screen of a raster pattern monitor 43, such as a conventional television screen.

The scanned storage 27 has an output to and receives an input from the computer storage or so-called permanent storage" or computer memory, as aforesaid, through a suitable control circuit 32. The computer storage and the means for accessing the storage are well known in the art and are therfore neither illustrated nor described in any substantial detail herein. The computer storage C will normally assume the form of a magnetic drum or disc of the type capable of having digital data recorded thereon. The control circuit 32 which permits accessing of the computer storage C is normally provided with a control panel and may be included with the computer; it being understood that the system S of the present invention is essentially auxiliary or peripheral to the computer.

A number of commercially available read-only memories can be used in the system of the present invention. As indicated above, however, one of the read-only memories 35 will be described in detail and one of the preferred forms of programmable read-only memories is more fully illustrated in FIG. of the drawings. This programmable read-only memory 35 includes a word select matrix 44 receiving the fout bit inputs from the row counter 33 and which are designated as R R R and R The bit-7 input designated as B-7" is introduced into an enable gate 45 and the four outputs of the word select matrix 44 are anded with an enable output from the gate 45 in a series of four AND gates 46. The outputs of each of the AND gates 46 are introduced into a decoding matrix 47 which contains a serics of memory elements, such as flip-flops (not shown). The decoding matrix 47 permits the generation of six outputs, each passing through output buffers 48 which thereby produce the six line count outputs D and D through D and these six line count outputs are introduced into the gating circuit 39.

This type of programmable read-only memory can be programmed electronically after manufacturing, or during manufacturing by designing the final metalization to correspond to the desired memory configuration. Furthermore, the programmable read-only memory 35 described above can be programmed by alteration of the specific memory elements included in the decoding matrix 47 to create logical ones" and locigal zeros" in selected bit positions.

The operator of the system of the present invention can compose essentially any graphic character using either the plural-point pattern or the plural-bar pattern and in order to generate the characters which form the graphic diagram the operator will actuate the various push-button switches on the graphic keyboard 10. As the switches are actuated, the internal lights in these switches will illuminate. When the operator is satisfied that the character has been composed correctly, the load switch 24 will be actuated so that the eight-bit word representing the entered character may be transferred to the scanned memory 27 which essentially serves as a temporary storage. The push-button switches on the graphic keyboard 10 which have been actuated will still remain illuminated so that the operator may then position the cursor to the next location and enter the same graphic character again by actuating the load switch 24. In like manner, the operator may reset the switches by actuating the clear switch 25 which extinguishes all of the keyboard lights after the memory 27 has been cleared. The operator may thereafter compose a new graphic character by actuating any of the push-button switches l923. Thus, in order to draw a continuous straight line, it is only necessary to set up the first character, such as through actuation of the switches 19 and 20 or 21 and 22, repeatedly step the cursor 26, and actuate the load switch 24.

Alpha-numeric characters may be introduced along with the graphic characters in the graphic display in order to provide a total informational display and these alpha-numeric characters may be injected substantially anywhere on the screen with respect to the graphic characters. As indicated above, the one limitation regarding the generation of the alpha-numeric characters and the graphic characters is that only one character can be stored in any one raster location, whether a graphic character or an alpha-numeric character. Once the complete diagram has been composed, the page representing that diagram is located in the scanned store 27 and this page may then be introduced into the permanent storage 32 under computer control. A standard eight-bit data communication code, such as the ASCII code, may be used to transmit all of the graphic and/or the alpha-numeric data.

An informational diagram entered into a computer storage by the above means may be recalled under computer control at any time and upon recall this diagram, in the form ofa page, will be transferred from the permanent storage 32 to the scanned store 27 where the page will again be displayed through the screen of the monitor 43. Recall in this form may occur in either the modification or presentation modes of operation. In the presentation mode of operation the informational display will be reproduced in its original form upon demand and in the modification mode, the origninal display will be altered as described above.

A six-bit address word which provides line count information to the gating circuit 36 and to the gating circuit 36' is provided in each of the thirty-two locations in each of the read-only memories 35 and 35'. As the address of the read-only memory 35 is scanned by the advancing row counter 38, the six-bit address word read out of the read-only memory 35 is mixed in the gating circuit 36 with the six remaining bits of the data word in the buffer memory 30 to generate each graphic character. The alpha-numeric character is generated in substantially the same manner using the six bits of the data word in the buffer memory 30 when these six bits are detected to represent an alpha-numeric character. The structure of this gating circuit 36 (to be hereinafter described) and the gating circuit 36', as well as the format of the pattern program in the read-only memories 35 and 35 are such that upon mixing, an output is generated and this output will create a video-signal when applied to the eight parallel inputs of the main data register 40. Furthermore, the video-signal will be cleared as the main register 40 is clocked by the column counter 41.

For purposes of clarity, the portion of the gating circuit 36 used in the generation of the plural-bar graphic output is illustrated in FIG. 6 and the portion of the gating circuit 36 which is used in the generation of the plural-point graphic output is illustrated in FIG. 7, the combination of these two gating structures forming the gating circuit 36 and being schematically illustrated in FIG. 8.

Gating circuit 36' of the type used in the generation of alpha-numeric characters are known in the art and therefore the gating circuit 36 is neither illustrated nor described in any further detail herein.

As indicated previously, only four bits in the eight-bit word are used to generate any of the bars in the plural bar font pattern and the four bits which describe the bars in any such font are the four least significant bits, B-l through 8-4, of this eight-bit word. Therefore, in the generation of a plural-bar font pattern, the bits will assume the following conditions:

8-8 l Distinguishes between graphic and alphanumeric characters.

B-7 II 0 Distinguishes between the four-bar and six-point pattern.

B-6 M M is either a "0 or 1" state.

B-S M B-J N N is assigned a or 0" state according to the combination of bars in the four-bar pattern to be displayed.

The gating circuit 36 comprises a plural-bar gating structure 49 which generally includes six input NAND gates G1 through G6. It can be observed that the NAND gates G1 through G4 receive the first four least significant bits in a data word generated by actuation of any of the keys on the plural-bar keyboard block 17. The gates G5 and G6 also receive bits B-2 and B-4, respectively. In like manner, the input NAND gates, G1 through G6 receive the respective address line counts D through D, generated in the read-only memory 37. The outputs of the NAND gates G1, G3, G5 and G6 are combined in a NAND gate G7 which produces column and 0 outputs. The output of the input gate G2 is introduced into another NAND gate G8 which provides column outputs 0 0 and 0 Finally, the output of the input NAND gate G4 is introduced into a NAND gate G9 which provides

column outputs

0,, 0 and 0 It can be observed by reference to FIG. 6 that these outputs 0 through 0 are introduced into the main shift register 40 for ultimate mixing with a television input signal.

Actuation of all of the keys 19 through 22 on the keyboard block 17 will generate a bar pattern equilvalent to that illustrated in FIG. 3a and thus, it can be seen that all twelve locations in

rows

0 and 1 through 11 will be illuminated at

output columns

0 and 0,. In like manner, rows 5 and 6 in the font will be illuminated at all columns 0, through 0 In this case, bits B-l through 84 will each assume a one" state upon actuation of all such keys 19 through 22. Further, it can be observed that bit 5-! will cause the illumination of

output columns

0 and 0 in rows 0 through 4; bit 8-2 will cause illumination of rows 5 and 6 in output columns 0 0 and 0 bit B-3 will cause illumination of

columns

0 and 0 in rows 7 through 11; and bit B-4 will cause illumination of rows 5 and 6 in columns 0 through 0 Generation of any bars in a font by means of any one or more of bits 3-] through B-4 will cause illumination of the center section of the font (shaded area in FIG. 3a), namely rows 5 and 6 in columns 0., and 0,.

Actuation of the keys on the keyboard block 17 to produce the four-bar font pattern just described will render a logic output from the read-only memory 35 in accordance with the chart illustrated in FIG. 3b. It'can be seen that the address line count D will achieve a logical one" state in rows 0 through 6, address line count D will achieve a one" state in rows 5 through 11 and further, rows 5 and 6 will achieve a "one state in each of address line count outputs D, and D ln row 0, only the bit 8-1 is relevant and if the bit 8-1 is one" then positions 4 and 5 in this row 0 will be illuminated. The row count lines from the counter 38 are used to address the read-only memory 35 in the manner as previously described and on line 0, the output word form the memory 35 is 1000000. When this output is applied to the gating structure illustrated in FIG. 6, along with bits 8-! through B-4 applied to gates G1 through G4, respectively, it can be seen that gate G1 will produce a zero" output, while each of gates G2 through G6 will each produce a one" output. Gate G7 will produce a one" output since not all of the inputs to the gating structure 49 is a one" input. Thus, outputs 0 and 0 will be generated and therefore a logical one is loaded into positions 4and 5 of the main register 40. Further, if the data for row 0 is clocked out of the main register 40, the two central positions in the line, namely positions 0, and 0 are illuminated.

The same procedure is followed in determining the status of any other dot in the four-bar pattern illustrated in FIG. 3a for purposes of illumination. Thus, for rows 0 through 4, the same procedure will follow if B-] is a logical one for these rows. in rows 5 and 6 several possibilities exist so that if bit 8-4 is a logical "one" then positions 0, through 0,, will be illuminated and if bit 3-2 is a logical one," then positions 0 through 0 of these rows 5 and 6 will be illuminated. Furthermore, if bits B-2 and B4 are both logical ones," then the word which emerges from the read-only memory 35 on rows 5 and 6 is l l 1 ll 1. Thus, it can be seen for example, that a vertical bar through the entire twelve dot by eight dot raster location would be described by the character IOXXOlOl.

As indicated previously, if any one of bits 8-] through B-4 achieve a logical one state then the center shaded area in FIG. 3a, namely positions 0 and 0, in rows 5 and 6 will be illuminated. The outputs for the logical states of bits B-l through 8-4 in a data word are as follows:

a. If bit B-l is a logical one, the output of gate G1 is zero and

outputs

0 and 0 are true;

b. If bit 8-2 is a logical two" the output of gates G2 and G5 are zero and outputs 0 0 0 0., and 0, are true;

c. If bit 3-3 is a logical one, the output of gate G3 is zero" and outputs 0 and 0, are true; and

d. If bit 84 is a logical one the output of gates G4 and G6 are zero" and outputs 0,, 0,, 0 0 and 0, are true.

Illumination of rows 7 through 1 1 in the raster location are generated in substantially the same way as rows 0 through 4 and thus, it can be observed that the pattern generated through the programmable read-only memory 35 interacts with bits B-l through 3-4 to produce the four-bar pattern. It should be observed, that other plural-bar patterns, such as a five-bar and six-bar pattern could also be generated. In this case, a larger data word would probably be employed so that if a six-bar pattern is used, a ten-bit data word would be generated. In addition, the read-only memory 35 would be expanded as well as the gating structure 49 in order to accommodate the additional outputs which are generated.

As mentioned above, six bits in the eight-bit word are used to generate any of the points in the plural-point font pattern and the six bits which describe the points in the font appearing in any such raster location are the six least significant bits B-l through 84 of this eight-bit word. Therefore, in the generation of a plural-point font pattern. the bits will assume the following logical conditions:

8-8 I l Dlltingulshel between graphic and alphanumeric characters.

5-7 I 0 Dlltinguilhes between the four-bar and six-point pattern.

B-3 N N is assigned a one" or "zero state according to the combination of points to be displayed in the six-point pattern.

The gating circuit 36 also comprises a plural-point gating strucutre 50 which generally includes six input NAND gates G11 through G16. It can be observed that the NAND gates G11 through G16 receive the first six least significant bits in a data word generated by actuation of any of the keys 23 on the keyboard block 18. In like manner, the input NAND gates G11 through G16 receive the respective address line counts D through D, generated in the read-only memory 35. The outputs of the NAND gates G11, G13 and G15 are combined in a NAND gate G17 which produces a column and a column 0 output. The outputs of the NAND gates G12, G14 and G16 are combined in a NAND gate G18 which renders a column output 0 and a column output 0 It can be observed by further reference to FIG. 7 that the outputs 0 0 0 and 0 from the respective gates G17 and G18 are introduced into the main register 40 for ultimate mixing with a television input signal.

It can be observed that actuation of all of the keys 23 on the keyboard block 18 will generate a point-pattern equivalent to that illustrated in FIG. 2a. Thus, it can be seen that

row locations

1, 2, 5, 6, 9 and 10 will be illuminated at output columns 0 0 0 and 0 in the manner as illustrated in FIG. 2a. In this case, bits B-l through B-6 will assume a one state upon actuation of all of the keys 23 on the keyboard block 18. Further, it can be observed that bit B-1 will cause illumination of

output columns

0 and 0,, in rows 1 and 2; bit 13-2 will cause illumination of

output column locations

0 and 0 in rows 1 and 2; bit B-3 will cause illumination of

output column locations

0 and 0 in rows 5 and 6; bit 3-4 will cause illumination of

output columns

0 and 0 in rows 5 and 6; bit 8-5 will cause illumination of

output column locations

0 and 0 in rows 9 and 10; and bit 8-6 will cause illumination of output column locations 0 and 0-, in rows 9 and 10.

Actuation of all of the keys 23 on the keyboard block 18 to produce the six-point font pattern illumination just described will render an output from the read-only memory 35 in the manner as illustrated in FIG. 2b. It can be seen that the address line count D and the address line count D will achieve a logical one state in rows 1 and 2, address line counts D and D will achieve a logical one state in rows 5 and 6, and further, address line counts D and D will achieve a logical one state in each of rows 9 and 10.

It can be observed that none of the bits B-l through 8-6 are relevant with regard to

rows

0, 3, 4, 7, 8 and 11 and no illumination will occur in any of these rows in any raster location. Considering row 1, it can be observed that the only bits which are relevant are bits B-1 and 8-2. The row count lines from the row counter 38 are used to address the read-only memory 35 in the manner as previously described and in the case where bits B-1 and 8-2 are relevant in rows 1 and 2, the output word from the memory 35 is 110000. When this output from the memory 35 is applied to the gating structure 50 illustrated in FIG. 7, and where either bits 8-] and 8-2 are applied to gates G11 and G12, it can be seen that gates G11 and G12 will produce a logical one" output while each of gates G13 through G16 will produce a logical zero" output. Hence, the outputs at gates G17 and G18 will be logical ones to thereby render

outputs

0,, 0 0 and 0 true.

The four possible combinations of bits B-1 and 8-2 are set forth in the following table:

Gnte Outputs Outputs 8-2 3-1 011612

G17 G18

0 ,0 0 ,0 0 0 l l 0 0 0 0 O l l O l l Thus, by an examination of the above, table, it can be observed that if only bit 8-1 is relevant, gate G11 will produce a logical zero" output and gate G12 will produce a logical one" output thereby

rendering outputs

0 and 0;, true and gate G18 will produce a logical zero output thereby rendering outputs 0 and 0-, not true. Further, if bit 8-2 is the only relevant bit in rows 1 and 2, it can be observed that gate G11 will have a logical one" output and gate G12 will have a logical zero" output. Moreover, gate G27 will have a logical one output, thereby

rendering outputs

0 and 0 true.

A similar logical process occurs with regard to rows 5 and 6 where bits B-3 and B-4 are the relevant bits. In this case, it can be observed that if the switches 23 on the keyboard block 18 are actuated in proper manner, bit B-3 and bit 8-4 will be relevant thereby producing a logical zero" output at gates G13 and G14 and also at G17 and G18. Therefore, all of the outputs 0 0 0 and 0, will be rendered true. Hence, it can be observed that the pattern stored in the programmable read-only memory 35 interacts with bits B-l through 8-6 of a character word to produce the six-point pattern.

The outputs for the logical states of bits B-l through 8-6 in a data word are as follows:

a. If bit B-l is a logical one, the output of gate G11 is zero" and outputs 0 and 0 are true;

b. If bit 8-2 is a logical one," the output of gate G12 is zero and

outputs

0 and 0 are true;

c. If bit 3-3 is a logical one," the output of gate G13 is zero and outputs G2 and G3 are true;

d. If bit 8-4 is a logical one," the output of gate G14 is zero and

outputs

0 and 0 are true;

6. If bit B-5 is a logical one," the output of gate G15 is zero and

outputs

0 and 0 are true; and

f. If bit B-6 is a logical one, the output of gate G16 is zero" and outputs 0 and 0 are true. In accordance with the above, any combination of the foregoing will produce a font pattern of any selected points when the bits controlling these points are logical ones.

It should be observed that other plural-point patterns such as a ten-point or twelve-point pattern could also be generated. In this case, a larger data word would also be employed so that if a ten-point pattern is used a ten-bit data word would be generated. In addition, the read-only memory would be expanded as well as the gating structure 50 in order to accommodate the additional outputs which are generated.

FIG. 8 is a schematic view of a combination of the

gating structures

49 and 50 to produce the gating circuit 36. It can be observed that the NAND gates G11 through G16 as well as G5 and G6 in the gating structure 49 serve as the combination input gates. Gates G7, G17 and G18 are also employed in the manner as illustrated in FIG. 8. By examining the logic of the

gating structures

49 and 50, it can be observed that the output of the gate G12 which is essentially a combination of gates G12 and G2 renders outputs of 0, when combined with bits 13-7 and 13-8 in a NAND gate G19. The output of gate G7 is combined with a bit B-8 input and a not bit B-7 input in a NAND gate G20 and generates

outputs

0, and 0 The output of gate G18 is combined with the bit 13-8 input in a NAND gate G21 and generates

outputs

0 and 0 The output of gate G17 is com- Ell bined with the bit 8-8 input in a NAND gate G22 and, therefore, renders an output of and 0 Finally, the output of gate GM is combined with the bit 8-7 and bit B-8 inputs in a NAND gate G23 to render an output 0,. It can be observed that the bit B5 and bit 13-6 inputs are anded with the bit B-7 inputs in NAD gates G24 and G25 respectively, before being introduced into the respective NAND gates G and G16. All of these aforesaid outputs are introduced through a gating matrix 51 consisting of eight NAND gates which are, in turn, connected to the main data shift register 40 in the manner as illustrated in FIG. 8. For the purpose of describing the gating circuits of FIGS. 6 8, the bits which have been designated as B-(x) such as 8-5 have been illustrated as B such as B, in the drawings.

It can be seen that the display system of the present invention is highly effective with standard display monitors using a raster pattern, and particularly with television monitors for displaying both alpha-numeric and graphical characters in order to generate a complete informational display. The system of the present invention is highly effective in that it is capable of accepting ASCII coded alpha-numeric data for display on one or more television monitors and in addition, the composite of the television input with the video-signal produced by the system of the present invention is compatible with substantially any commercially available television monitor. Furthermore, it is possible to write in the main register 40 through actuation of the keyboards 10 and 11 and to record this information into the computer storage C through the control circuit 32. The generated graphical characters are formed by pluraj-point or plural-bar font patterns and the nature of these displays lends to easy viewability. Moreover, the system of the present invention is very conventient to author and present conceptual information for construction purposes.

The components in the system of the present invention have been uniquely selected so that the graphic characters generated by the system S would be displayed along with the standard alpha-numeric data and further, the graphical information uses a data format which is completely compatible with the data format of alpha-numeric information. In addition, the same storage medium which is used for the retention of alphanumeric data is also used for the retention of the data representing graphic characters. Thus, the data for the graphical characters could be randomly stored in a computer memory along with the alpha-numeric data or separated therefrom. The exact addressing scheme used in the computer is not part of the present invention since the system S of the present invention is peripheral thereto, as stated above. However, one effective form of recording a page containing alpha-numeric characters and graphical characters employs a modified form of associative addressing where the data representing the graphical characters can be stored in positions related to the storage positions of the alphanumeric data.

There are many auxiliary components which can be used with the system S of the present invention and many substitutes of components which can be made. For example, a vido-signal generator could be used in place of the mixer 42 for converting the generated characters and the television input into a composite video-signal and for also providing timing and synchronizing pulses. Furthermore, either fast or slow memory organizations may be employed depending on the requirements of the user of this system.

The system of the present invention may also be provided on, an optional protection control for displaying fields of fixed data and fields of variable data. In this control system memory locations allocated to fixed data are placed in a protect condition to prevent the fixed data from being erased or read out and to enable the operator to erase only the variable data. A protection control is provided for permitting the operator to hold the data constant in the protection fields while varying the data in the non-protected fields. When the protection control is off, all character locations will be unprotected and the data may be entered or altered in any location. When the protection control is switched on, the data in the assigned locations will thereafter become protected. The fields assigned to the protected and variable data may be of any length. Furthermore, this protection control system could be constructed in such manner that the protected characters written into the computer memory C will be displayed at half of normal intensity.

It should be understood that the display system of the present invention is not limited to the exact configuration illustrated in the drawings and that many changes, modifications, variations and other uses and applications of the subject system will, however, become apparent to those skilled in the art after considering this specification and the accompanying drawings. All such changes, modifications, variations and other uses and applications which do not depart from the spirit and scope of the invention are deemed to be covered by the invention which is limited only by the claims which follow.

We claim:

l. A system for generating graphic displays on the screen of a monitor having a plurality of raster locations thereon and being operable with a raster, said system comprising memory means, control means operatively connected to said memory means for controlling same, first pattern forming means including selected locations in said memory means and operating in conjunction with said control means for generating a first type of graphic character elements combinable in a single raster location toform a graphic character, first switch means operatively associated with said first pattern forming means to select certain of the first type of character elements in a desired arrangement and combined to form a first graphic character in a raster location, second pattern forming means including other selected locations in said memory means and operating in comprising memory means, control means withsaid control means for generating a second type of character elements combinable in a single raster location to form a graphic character, said second type of graphic character elements differing in appearance with respect to said first type of graphic character elements, second switch means operatively associated with said second pattern forming means to select certain of the second type of character elements in a desired arrangement and combined to form a second graphic character in another raster location, means operatively associated with said first switch means and second switch means and said first and second pattern forming means for generating a signal permitting selective generation of either said first type of graphic character elements or second type of graphic character elements, and cursor means to position the various graphic characters formed from said types of character elements in a desired arrangement to form a graphic display.

2. The system for generating graphic displays of claim 1 further characterized in that the first pattern forming means generates bar-type character elements, and that said second pattern forming means generates point-type character elements.

3. The system for generating graphic displays of claim 1 further characterized in that the first pattern forming means generates bar-type character elements and that a maximum of four of such bar-type elements constitutes the graphic character in any one raster location, and said second pattern forming means generates point-type character elements and that a maximum of six of such point-type elements constitutes the graphic character in any one raster location.

4. The system for generating graphic displays of claim 1 further characterized in that means is provided for adding alpha-numeric characters to the graphic displays in order to generate a composite informational display of graphic characters and alpha-numeric characters.

5. A method for generating graphic-type displays on the screen of a monitor operable with a raster, said method comprising establishing a plurality of raster locations of predetermined font size on the screen associated with the monitor, generating and introducing first input signals to a memory, generating a first type of character elements from said first input signals and which are combinable to form graphic characters of said predetermined font size in certain of said raster locations, generating and introducing second input signals to said memory, generating a second type of graphic character elements from said second input signals which are distinct from said first type of character elements and combinable to form graphic characters of said predetermined font size in certain other of said raster locations, generating a characterization signal which characterizes either the first type of graphic character elements or the second type of graphic character elements for each particular raster location, transmitting the characterization signal to said memory and selecting the proper types of character elements for each raster location therefrom, and positioning the graphic characters formed in said raster locations in a desired arrangement to form a graphic display.

6. The method of claim 5 futher characterized in that the first type of character elements are bar-type character elements and that the second type of character elements are point-type character elements.

7. The method of claim 5 further characterized in that the first type of character elements are bar character elements and that a maximum of four bars can exist in any one raster location, and that said second type of character elements are points and that a maximum of six points can exist in any one raster location.

8. The method of claim 5 further characterized in that each graphic character is stored, processed and transmitted as an eight-bit data word.

9. The method of claim 5 further characterized in that alpha-numeric characters are generated and displayed along with the graphic characters.

10. A display system for interactive computer display terminals, said system comprising a first input means capable of generating a multi-bit binary graphic word, said first input means comprising first selection means enabling generation of a first type of graphic character elements and second selection means enabling generation of a second type of graphic character elements, characterization means also operatively associated with said first input means to generate a first characterization element comprised of at least one bit to distinguish between said first and second types of graphic character elements, each of said first type and each of said second type of graphic character elements defined by one binary word being combinable in a single raster location to form a graphic character therein, second input means capable of generating a multi-bit binary alpha-numeric data word, first storage means operatively associated with said first input means to receive certain bits of said multi-bit graphic word and said first characterization element, second storage means operatively associated with said second input means to receive certain bits of said multi-bit alpha-numeric data word, means operatively associated with said first and second input means to generate a second characterization element to distinguish between said graphic words and alpha-numeric data words, selector means operatively connected to said first and second storage means to receive said graphic words and alpha-numeric data words and said second characterization element and select between alpha-numeric data words and graphic words, and clocking means for clocking either said graphic words or alpha-numeric data words to said monitor to display characters defined by said words.

11. The system of claim 10 further characterized in that a main register is operatively connected to said selector means to receive either the graphic work or alpha-numeric data word selected by said selector means, and said clocking clocking means is operable with said main register to generate a video-signal from the word received by said main register.

12. The system of claim 11 further characterized in that a mixer is provided for receiving the video-signal and a television type input signal and forming a signal complex therefrom for display through said interactive computer display terminals.

13. The system of claim 10 further characterized in that the display system for the interactive computer display terminals is a monitor having a screen operable by a raster pattern.

14. The system of claim 10 further characterized in that the display system for the interactive computer display terminals is a television monitor.

15. The system of claim 11 further characterized in that said clocking means is a column counter for determining a particular column in a raster location, and that row counter means is operatively associated with said first and second storage means for determining the row location in any of the columns in said raster location.

16. The system of claim 10 further characterized in that said first storage means comprises a first memory and a first gating circuit which are operatively connected to said selector means and said second storage means comprises a second memory and a second gating circuit which are operatively connected to said selector means.

17. The system of claim 16 further characterized in that said first memory and said second memory are read-only memories.

18. The system of claim 10 further characterized in that said first selection means comprises first switchtype means for generating plural-bar character elements and said second selection means comprises second switch-type means for generating plural-point character elements.

19. Circuit active means for determining the coordinate positions of two types of distinct character elements in a raster location on a display screen and where said character elements are combinable in a desired arrangement to form characters, said circuit active means comprisng a receiving memory device for receiving a multi-bit word defining the character elements and representing a character comprised of said character elements, a gating matrix for receiving certain of the bits of said multi-bit work defining the character elements, a character generating memory device receiving another bit from said multi-bit word characterizing the type of character elements, first location counter means operatively connected to said character generating memeory device and generating signals representing a first coordinate axis location for said elements, said last named signals being introducable into said gating matrix for gating certain of the bits representing certain of the character elements from said gating matrix, register means operatively connected to said gating matrix on receiving the gated bits, and second location counter means operatively connected to said register means and being operable with the certain gated bits to determine a second coordinate axis location which is relatively perpendicular to said first axis location to thereby define the coordinate positions of the character elements in said raster location.

20. The circuit active means of claim 19 further characterized in that said receiving memory device is a buffer memory and said character generating memory device is a read-only memory unit.

21. The circuit active means of claim 19 further characterized in that said receiving memory device is a buffer memory and said character generating memory device is a programmable read-only memory.

22. The circuit active means of claim 19 further characterized in that a plurality of different types of character elements can be used to generate the graphic characters and that the bit introduced into said receiving memory device represents the type of character elements introduced into said gating matrix.

23. The circuit active means of claim 19 further characterized in that said characters are graphic characters and that a plurality of different types of character elements can be used to generate different graphic characters, one of said character element types comprising a series of bar-lik elements and the other said character element types comprising a series of point-like elements, the bit of said multi-bit word introduced into said receiving memory device characterizing between the point-like elements and the bar-like elements.

24. A data output circuit for gating certain bits of multi-bit words in response to a plurality of input signals and where certain of the bits in certain of said multi-bit words represent information bearing graphical elements and certain of the bits in other of said multi-bit words represent an information bearing alpha numeric element and a characterization bit in said multi-bit words distinguishes between said two types of elements; said data output circuit comprising a plurality of first gating members receiving certain of the bits of multi-bit word, memory type signal generating means receiving the characterization bit, a plurality of second gating members also receiving certain of the bits of another multi-bit word, second memory type signal generating means also receiving said characterization bit, first clocking means for generating first clock signals and introducing said first clock signals into each said signal generating means, each said signal generating means generating a plurality of input signals in response to said clock signals upon receipt of a selected characterization bit and introducing said input signals to said gating members thereby gating certain of said bits from the gating members which have received such bits in response to certain of the input signals, register means for receiving said gated bits, and second clocking means for introducing clocking signals into said register means for transmitting said gated bits on a serial basis.

25. The data output circuit of claim 24 further characterized in that each said signal generating means is a read-only memory unit and which memory unit comprises a decoding matrix and a word select matrix.

26. The data output circuit of claim 24 further characterized in that said gating members are NAND gates and includes a number of NAND gates at least equivalent to the number of bits in said multi-bit word representing the first type of elements.

27. The data output circuit of claim 24 further characterized in that the input signals to said gating members are signals designating a first coordinate location position and the clocking signals generated by said second clocking means are signals designating another coordinate location position.

28. The method of displaying graphical information along with alpha-numeric information through computer interactive display terminals and where the graphic information comprises at least two types of character elements combinable to form at least two different types of graphical characters, said method comprising generating a multi-bit word representing each alpha-numeric character, generating a multi-bit binary word of the same binary length as the first named binary word and representing one of said two types of graphical characters, generating a multi-bit binary word of the same binary length as the first named binary word and representing the other of said two types of graphical characters, processing all of said multi-bit binary words in substantially the same manner, and displaying the multi-bit words as graphical and alphanumeric characters on the display screen of a monitor.

29. The method of claim 28 further characterized in that each of said multi-bit words comprise eight binary bits.

Claims

1. A system for generating graphic displays on the screen of a monitor having a plurality of raster locations thereon and being operable with a raster, said system comprising memory means, control means operatively connected to said memory means for controlling same, first pattern forming means including selected locations in said memory means and operating in conjunction with said control means for generating a first type of graphic character elements combinable in a single raster location toform a graphic character, first switch means operatively associated with said first pattern forming means to select certain of the first type of character elements in a desired arrangement and combined to form a first graphic character in a raster location, second pattern forming means including other selected locations in said memory means and operating in comprising memory means, control means with said control means for generating a second type of character elements combinable in a single raster location to form a graphic character, said second type of graphic character elements differing in appearance with respect to said first type of graphic character elements, second switch means operatively associated with said second pattern forming means to select certain of the second type of character elements in a desired arrangement and combined to form a second graphic character in another raster location, means operatively associated with said first switch means and second switch means and said first and second pattern forming means for generating a signal permitting selective generation of either said first type of graphic character elements or second type of graphic character elements, and cursor means to position the various graphic characters formed from said types of character elements in a desired arrangement to form a graphic display.

18. The system of claim 10 further characterized in that said first selection means comprises first switch-type means for generating plural-bar character elements and said second selection means comprises second switch-type means for generating plural-point character elements.

28. The method of displaying graphical information along with alpha-numeric information through computer interactive display terminals and where the graphic information comprises at least two types of character elements combinable to form at least two different types of graphical characters, said method comprising generating a multi-bit word representing each alpha-numeric character, generating a multi-bit binary word of the same binary length as the first named binary word and representing one of said two types of graphical characters, generating a multi-bit binary word of the same binary length as the first named binary word and representing the other of said two types of graphical characters, processing all of said multi-bit binary words in substantially the same manner, and displaying the multi-bit words as graphical and alpha-numeric characters on the display screen of a monitor.