JPS6132677B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a display control device for a scanning display, and more particularly to a display control device for displaying characters in the form of dots, lines, or a combination thereof on the screen of a scanning display.

For example, in a video game device, a background image is displayed in conjunction with displaying various characters. Such background images are used in games such as those that display dot-like characters at appropriate positions on the screen to represent stars, lines that partition areas used in games, or lines of latitude and longitude on the screen. A variety of lines are known to be used.

A character ROM system is known as a conventional device for displaying an image such as a background using points, lines, or a combination thereof. In the conventional character ROM method, each pixel is divided into multiple pixels in the horizontal and vertical directions, the horizontal and vertical coordinates are determined for each pixel, and a dedicated memory containing a storage area corresponding to each pixel is used. (ROM) was used. When a star is to be displayed as a background image, both horizontal and vertical coordinate data for displaying the star are stored in memory in the order of addresses in accordance with the scanning order of the electron beam. Furthermore, when displaying a line as a background image, the horizontal and vertical coordinates on the screen at which the line should be displayed are continuously stored in a memory. If you want to display the background image using Character ROM method,
The display of points was controlled by reading data at an address determined by the logical product of the output of a horizontal counter and the output of a vertical counter, which were incremented in synchronization with the scanning of the electron beam of the scanning display.

For this reason, the conventional character ROM method required a memory capacity of 16k bits or 16k words even when divided into 128 pixels in the horizontal direction and 128 pixels in the vertical direction. . Therefore, conventional devices for controlling the display of background images have had problems in that the storage capacity of the memory has become extremely large, and the structure has become complicated and expensive.

Therefore, an object of the present invention is to provide a method that can store various image data in a memory with a minimum storage capacity and is inexpensive when drawing characters using dots, lines, or a combination thereof on the entire screen of a scanning display. An object of the present invention is to provide a display control device for a scanning type display.

To summarize, the present invention stores at least coordinate data in the scanning direction in which points are to be displayed sequentially in the traveling direction of the electron beam and sequentially in the scanning order of the scanning lines. Then, when the coordinate data in the scanning direction for displaying at least a point read from the memory matches the coordinate data at the actual display position of the electron beam, the read address in the memory is incremented to the next read address. The display is controlled.

Hereinafter, specific embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a circuit diagram of a display control device for a scanning type display according to an embodiment of the present invention.

A scanning display (not shown) to which the present invention is applied is, for example, a raster scan type display.
A CRT display is used. Such a scanning display may be of either a progressive scan type or an interlaced scan type. In the following description, a progressive scanning television cathode ray tube (CRT) display will be described as an example of a scanning display.

In the configuration, the display control device of this embodiment has the following configuration:
Basically, it includes a synchronizing signal generating circuit 11, a memory (ROM) 12 which is an example of a storage means for storing background image data, an address counter 13 for specifying a read address of the ROM 12, and a coincidence detecting means 14.

Next, a specific configuration of the display control device will be explained. The synchronization signal generation circuit 11 includes a reference clock oscillation circuit 111. This reference clock oscillation circuit 111 has a frequency (corresponding to twice the period of scanning the electron beam (i.e., luminance signal) for one pixel when the horizontal direction of the CRT display is divided into a plurality of pixels (for example, 128). for example
24, 576 MHz) is generated and applied to the horizontal frequency division counter 112. This horizontal frequency division counter 1
12, an N-ary counter is used. Here, the N-ary number is the sum of twice the number of divided pixels in the horizontal direction (128) (i.e. 256) and the number of pulses corresponding to the horizontal blanking period (horizontal retrace period) (for example 128). (384). The coded information representing the count value of the horizontal frequency division counter 112 is stored in the horizontal timing signal generation memory (H-ROM).
113 and a coincidence circuit 141 included in the coincidence detection means 14. The H-ROM 113 generates a horizontal synchronization signal HBL during a pulse period (ie, 128H) representing a horizontal blanking period. Further, the H-ROM 113 derives a pulse for each horizontal scanning line and supplies it to the vertical frequency division counter 114, and further supplies the pulse to the horizontal frequency division counter 112 as a reset pulse. The vertical frequency division counter 114 is
Equivalent to the number of pixels divided in the vertical direction of a CRT display, that is, twice the number of horizontal scanning lines on one screen (128) (i.e. 256) plus the value equivalent to the vertical blanking period (e.g. 8). do
266 hexadecimal counter is used. The coded information of this vertical frequency division counter 114 is given to a vertical timing signal generation memory (V-ROM) 115. This V-ROM 115 generates the vertical synchronizing signal VBL only for a period corresponding to the number of horizontal scanning lines (8) corresponding to the vertical blanking period. The horizontal synchronizing signal HBL and vertical synchronizing signal VBL thus generated are applied to the CRT display as synchronizing signals.

ROM1 for storing the background image data
2 includes a storage area of multiple addresses, and stores the coordinate data of only the horizontal direction of a point or line to be displayed on the CRT display screen in advance in each address in horizontal direction sequentially in the vertical direction of each horizontal scanning line. are doing. Note that the specific storage mode of the ROM 12 will be explained in detail with reference to FIG. 3, which will be described later.

The address counter 13 has a counted value incremented by the output of a coincidence detecting means 14, which will be described later, and uses the counted value to designate a read address in the ROM 12. The count value is reset for each ranking.

The coincidence detection means 14 detects the horizontal coordinate data read from the ROM 12 and the horizontal counter 112.
A coincidence circuit 141 detects a coincidence state with the count value of
and a one-pulse generation circuit 142 that generates one pulse in a relatively short period based on the output pulse of the matching circuit 141, and further includes
Includes NAND gates 143 and 144.

FIG. 2 is an illustrative diagram for explaining the operation of displaying dots or lines when the screen of a CRT display is divided into a plurality of pixels in the horizontal and vertical directions.

Figure 3 shows the case when displaying dots or lines on the CRT display screen shown in Figure 2.
3 is a diagram schematically showing an example of a storage state of coordinate data in a ROM 12. FIG.

Prior to explaining the operation of this embodiment, with reference to FIGS. 2 and 3, the storage state of data in the ROM 12 when displaying points or lines at the horizontal and vertical coordinate positions indicated by diagonal lines in FIG. 2 will be explained. do.

For example, the vertical coordinate V10 is the 10th vertical coordinate position of the horizontal scanning line, and the horizontal coordinate H1
If you want to display a point at the 0 position, use the vertical coordinate V1
In order to indicate that nothing is displayed on each horizontal scanning line from V1 to V9, coordinate data indicating that nothing is displayed (i.e., horizontal coordinate H0
coordinate data) are set and stored in advance.

Then, in order to display a point at the coordinate position determined by the AND of the vertical coordinate V10 and the horizontal coordinate H10, the coordinate data of the horizontal coordinate H10 is placed at the address next to the address corresponding to the vertical coordinate V9 (i.e., address 9). are set and stored in advance.

In addition, when displaying points at horizontal coordinates H8 and H15 in vertical coordinate V11, horizontal coordinates H8,
The coordinate data of H15 is stored sequentially.

Further, when nothing is displayed in one horizontal scanning line with the vertical coordinate V12, the coordinate data of the horizontal coordinate H0 is stored at the next address (address 12).

Furthermore, when displaying a line, the horizontal coordinate H of the starting end of the line at the vertical coordinate V13 where the line should be displayed.
Coordinate data corresponding to each horizontal coordinate position from 8 to the terminal horizontal coordinate H15 is stored in address order. Note that various other storage modes of the ROM for displaying lines can be considered, but these will be explained in other embodiments to be described later.

By the way, in this embodiment, only the horizontal coordinate data is stored in the ROM 12, so the 1st address is 7.
Bits are enough. In other words, if the ROM 12 in which address 1 is 8 bits is used, 1 bit will be left vacant. Therefore, in this case, the most significant bit (eighth bit) of the ROM 12 is used to store data identifying the type of character (eg, star or screen). Further, when it is necessary to display the screen upside down in a video game machine, an inversion signal is provided to the ROM 12.

Next, the specific operation of FIG. 1 will be explained with reference to FIGS. 1 to 3.

The address counter 13 resets its count value during the period when the vertical blanking signal VB is applied. Therefore, the first address (address 0) of the ROM 12 is designated. In this state, the horizontal frequency division counter 112 sequentially derives horizontal coordinate data H1, H2, . . . H128 in synchronization with the horizontal scanning of the electron beam of the CRT display. Then, at the timing when the horizontal frequency division counter 112 specifies the horizontal coordinate H0 (that is, during the horizontal retrace period), the coincidence circuit 141 detects that the coordinate data H0 of the first address read from the ROM 12 and the output of the horizontal frequency division counter 112 match. This is detected and a coincidence pulse c is derived. Accordingly, the one-pulse generation circuit 141 derives a pulse d having a constant time width from the start of output of the coincidence pulse. The output pulse of this one-pulse generating circuit 142 is given to the address counter 13 as a signal for instructing the count value to increment. Further, the output pulse of the one-pulse generation circuit 141 is given to the CRT display as a dot display command signal. However, the CRT display does not display anything because the horizontal scanning line is in retrace. Thereafter, in the same manner, the horizontal counter 11
The count value of 2 is the vertical coordinate V1 of the CRT display.
Similar operations are performed until 0 is specified.

Then, in a state in which the vertical coordinate V10 is designated, that is, in a state in which address 9 of the ROM 12 is designated, the coordinate data stored at address 9 in the ROM 12 (that is, the coordinate data of the horizontal coordinate H10) is provided to the matching circuit 141. In this state, when the count value of the horizontal frequency division counter 112 reaches the timing when the horizontal coordinate H10 is specified, the coincidence circuit 141 detects the coincidence state of both inputs and derives the coincidence pulse c. Accordingly, one pulse generation circuit 14
1 derives one pulse d. This one pulse is given to the address counter 13 as a step command signal, and is also given to the CRT display via either NAND gate 143 or 144 as a character signal for commanding a point to be displayed.

Note that when star or screen identification data is stored in the most significant bit (eighth bit) of each address in the ROM 12, the coincidence detection means 14 includes NAND gates 143 and 144. In this case, the output pulse of one-pulse generating circuit 142 is given as one input to each of NAND gates 143 and 144. This NAND gate 143 has
The 8th bit output of ROM 12 is given as the other input. The output of the NAND gate 144 is applied to the NAND gate 144 as the other input. The NAND gates 143 and 144 change their output logic states based on the output pulse of the one-pulse generating circuit 142 and the data of the most significant bit of the ROM 12 designated by the address. Therefore,
If star or screen identification data is stored in the 8th bit of address 9 of ROM 12,
NAND gate 14 corresponding to star or screen
3 or 144 is derived a signal commanding it to be displayed as a point.

Similarly, at the vertical coordinate V11, when the count value of the horizontal frequency division counter 112 reaches the timing when the horizontal coordinate H8 is specified, the coincidence circuit 141 again derives a coincidence pulse, and the one-pulse generation circuit 142 generates one pulse accordingly. do. As a result, pixels in a portion of the CRT display whose vertical coordinate is V11 and which corresponds to the horizontal coordinate H8 are displayed as dots (or star colors). Then, when the count value of the horizontal frequency division counter 112 reaches a value corresponding to the horizontal coordinate H15, a point is displayed in the same manner.

By the way, when displaying a line on the screen of a CRT display, by storing the data of each pixel in the horizontal scanning order in which the points are displayed in address order, it is possible to display a series of points, that is, a line. can be displayed.

As described above, according to this embodiment, when displaying a point on the screen of a CRT display, only the horizontal coordinate data is stored sequentially in the horizontal scanning direction in the vertical order of the horizontal scanning lines, and then read out from the memory. Since the address of the memory is moved based on the coincidence between the horizontal coordinate data and the horizontal coordinate position of the electron beam, it is possible to store the data for displaying a point using only the horizontal coordinate data. This has the advantage of reducing memory capacity by at least 1/2.

By the way, in the above embodiment, a case was described in which a line is displayed by a series of points, that is, a case in which horizontal coordinate data that is continuous in the scanning direction of one horizontal scanning line is stored sequentially, but the memory capacity can be further reduced. In order to do this, you can do the following.

For example, if you want to display a line at a horizontal coordinate position during a certain period of one horizontal scanning line, only the coordinate data representing the starting end of the line and the coordinate data representing the ending end of the line are sequentially stored in memory, and the starting end is One pulse may be generated continuously during the period from the coordinate data representing the coordinate data to the coordinate data representing the end. A specific configuration in that case is shown in FIG. That is, in FIG. 4, a flip-flop 145 with a trigger terminal is connected to the output terminal of the one-pulse generating circuit 142. During the period from when the one-pulse generation circuit 142 generates one pulse to when it generates the next pulse, a high level is continuously derived from the set output terminal of the flip-flop with trigger terminal 145. This allows a series of points, or a line, to be displayed while minimizing memory capacity.

As another example of displaying a line, if you want to display a line during the period from the start of a horizontal scanning line to a desired horizontal coordinate position, store the horizontal coordinate data of the desired horizontal coordinate position, that is, the end, in memory. In addition, an RS flip-flop is used in place of the flip-flop 145 with a trigger terminal. The RS flip-flop is set at the timing of the coordinate position H0 representing the start end of the horizontal scanning line, and the RS flip-flop is reset at the coincidence detection pulse of the horizontal coordinate data representing the end. In this way, the memory capacity can be further reduced.

On the contrary, if you want to display a line from a certain horizontal coordinate position to the end position of the horizontal scanning line, that is, H128, set the RS flip-flop with the output pulse of the one-pulse generation circuit 142, and generate a signal representing the horizontal coordinate position H0. The circuit can be configured so that the RS flip-flop is reset by In this way, the screen can be viewed by continuously displaying a line from the left edge of the CRT display in the horizontal direction to a certain coordinate position or from a certain coordinate position to the right edge, and repeating it for each vertical coordinate. At times, the screen of a CRT display appears to be divided by color or shading.

Note that the above-described combination of point display and line display can be applied to display various fixed characters such as characters.

As described above, according to the present invention, when drawing various characters on the scale of the entire screen, the memory capacity can be reduced, the number of parts can be reduced, and the cost can be significantly reduced. Unique effects such as the ability to reduce the area are achieved.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a display control device for a scanning type display according to an embodiment of the present invention. FIG. 2 is a diagram schematically showing the display state of the scanning display. FIG. 3 is a diagram schematically showing the storage contents of the memory (ROM) 12. FIG. 4 is a circuit diagram showing another embodiment of the coincidence detection means 14. In the figure, 11 is a synchronizing signal generation circuit, 12 is a horizontal coordinate data storage memory (ROM), 13 is an address counter, and 14 is a coincidence detection means.

Claims (1)

[Scope of Claims] 1. A display control device for displaying dots or lines on the screen of a scanning type display, wherein the scanning type display has a scanning direction in which one scanning line is divided into a plurality of pixels, and a scanning line is divided into a plurality of pixels. Coordinates are determined for each pixel in the direction, the coordinate data includes a storage area of multiple addresses, and the coordinate data corresponding to the coordinate position where at least a point is to be displayed on the screen of the scanning display is stored in one scanning line in the scanning line order. Storage means for presetting and storing addresses in order in the scanning direction; coordinate position data generation means for generating coordinate data representing coordinate positions at which each pixel should be sequentially scanned by the electron beam of the scanning display in the scanning direction; and the storage means. coincidence detection means for detecting a coincidence between the coordinate data read from the coordinate position data generating means and the coordinate data output from the coordinate position data generating means; A display control device for a scanning type display, comprising an address counter that specifies a read address of the storage means based on the counted value. 2. The scanning type display is driven by scanning an electron beam in the horizontal direction and repeating the horizontal scanning at regular intervals in the vertical direction, and a vertical blanking signal is sent every fixed number of horizontal scans on one screen. 2. A display control device for a scanning display according to claim 1, wherein the address counter resets its count each time the vertical blanking signal is applied. 3. The storage means stores coordinate data of at least one of the starting end and the ending end corresponding to the line coordinates at which a line formed by a collection of points in the horizontal direction on the screen of the scanning display is to be displayed, in address order. Claim 1 or 2
A display control device for a scanning display as described in Section 1. 4. The coincidence detecting means includes a pulse generating means for deriving a pulse during a period from the coordinate position corresponding to the coordinate data of the starting end stored in the storage means to the end of horizontal scanning.
A display control device for a scanning display as described in Section 1. 5. The scope of claim 5, wherein the coincidence detection means includes a pulse generation means for deriving a pulse during a period from the start of the horizontal scanning to a coordinate position corresponding to the rear end coordinate data stored in the storage means. 4. A display control device for a scanning display according to claim 3. 6. The display control device for a scanning display according to claim 1, wherein the coincidence detection means includes pulse generation means that generates one pulse only for a predetermined period of time after coincidence detection.