JPH0214717B2 - - Google Patents

Description

[Detailed description of the invention]

<Technical Field> The present invention mainly relates to displaying graphic images and text characters in a superimposed manner on a CRT screen in a personal computer system.
CRT display method, for details, displays black text characters overlaid on graphic images
Regarding CRT display method. <Prior Art> In a conventional personal computer system, a graphic image and a text character are displayed in a superimposed manner on a CRT screen using a configuration as shown in the block diagram of FIG. That is, in the conventional CRT display system, the graphic RGB signals Rg, Gg, Bg are sent to the palette circuit 20.
Text RGB signal as well as introduced through
RGB data selector 10 that introduces Rt, Gt, and Bt
and a NOR gate 30 as a selection gate circuit operated by text RGB signals Rt, Gt, Bt. When text RGB signals Rt, Gt, Bt are input to the RGB data selector 10, this text RGB signal Rt . text
Switches to RGB signal and displays text on CRT
RGB signals Rt, Gt, and Bt are sent out, so that text characters are displayed superimposed on desired locations on the graphic image. By the way, when a graphic image and a text character are displayed overlapping each other, and the colors of both images are bright, I would like to convert the color of the text character to black and display it in order to make the text character easier to see. However, conventional methods have not been able to provide such a display. This is because if you try to display a black text character superimposed on a graphic image, this black text character will cut out all of the text RGB signals Rt, Gt, and Bt that correspond to the image. Because it is formed by setting all color codes to "0",
For these black text RGB signals Rt, Gt, Bt, the NOR gate 30 does not output a selection signal,
RGB data selector 10 is a text RGB signal
Do not select Rt, Gt, or Bt. Therefore, the black text RGB signals Rt, Gt, Bt are
It is determined that it is transparent to the RGB signals Rg, Gg, and Bg, and a graphic image is displayed at the location corresponding to the black text character, and the black text character is not displayed at all. As mentioned above, with the conventional CRT display method, it is not possible to display black text characters over a graphic image on the CRT screen, and the expression form of overlay is limited, so it is possible to create an easy-to-read screen. It was inconvenient to do so. <Object of the Invention> The present invention has been made in view of the above-mentioned problems, and it is possible to display a black text character on a CRT screen by superimposing it on a graphic image, thereby achieving easy-to-see superposition. The purpose is to facilitate screen formation. <Structure of the Invention> In order to achieve the above object, the present invention includes an RGB data selector that introduces a graphic RGB signal and a text RGB signal, selects one of the RGB signals using a selection signal, and outputs the selected RGB signal to a CRT;
A selection gate circuit that introduces a text RGB signal and outputs a selection signal to the RGB data selector when any text RGB signal is input, and a selection gate circuit provided for each text RGB signal and a black display signal for each text RGB signal. and introduces a black display when no signal is input for each text
The present invention is characterized by comprising three black conversion gate circuits that send RGB signals to the RGB data selector and cut off the text RGB signal when a black display signal is input. <Example> Hereinafter, the present invention will be described in detail based on an example shown in the drawings. (B) First Embodiment Figure 1 is a block diagram showing the configuration of the CRT display system of the present invention.
RGB signals Rg, Gg, and Bg are input through the palette circuit 2, and text RGB signals Rt, Gt, and Bt are input to the other input terminal A, and one of the RGB signals is selected and output using the selection signal described later. Output from terminal Y to CRT (not shown). 3
is a NOR gate as a selection gate circuit that outputs the selection signal, and the text RGB signals Rt, Gt,
Bt introduces any text RGB signal Rt,
When Gt and Bt are input, a selection signal is sent to the input terminal S of the RGB data selector 1. In this embodiment, when the selection signal in RGB data selector 1 is at a high level, the graphic RGB
Signals Rg, Gg, Bg are selected and output,
When the selection signal is low level, the text
RGB signals Rt, Gt, and Bt are selected and output. 4 (4r, 4g, 4b)
is an AND gate which is a black conversion gate circuit, and is provided for each text RGB signal Rt, Gt, Bt, and introduces each text RGB signal Rt, Gt, Bt and black display signal Sb, and converts the black display signal
Each text RGB signal Rt when Sb is not input,
Send Gt and Bt to the RGB data selector 1,
When the black display signal Sb is input, the text RGB signals Rt, Gt, and Bt are cut off, that is, the text RGB signal
Set Rt, Gt, and Bt to low level. This black display signal Sb is for converting at least one of the text RGB signals Rt, Gt, and Bt into black and displaying it as a black text character, and in this embodiment, it is a signal that is in an active state at a low level. is generated and output according to instructions from a CPU (not shown). Next, the operation of the above configuration will be explained. black display signal
When Sb is not input to each AND gate 4r, 4g, 4b, that is, when the black display signal Sb is at high level, the graphic RGB signals Rg, Gg, Bg are input to the RGB data selector 1. Now, any text RGB signal Rt,
When Gt and Bt are sent in, AND gate 4
Since the black display signal Sb is at a high level at r, 4g, and 4b, the text RGB signals Rt, Gt, and Bt pass through these AND gates 4r, 4g, and 4b without being blocked, and are input to the RGB data selector 1. do. At the same time, the text RGB signals Rt, Gt, Bt are
Since it is also input to the NOR gate 3, a low level selection signal is output from the NOR gate 3, and this selection signal selects the text RGB signals Rt, Gt, Bt in the RGB data selector 1, and the output is Text from graphic RGB signals Rg, Gg, Bg
Switches to RGB signals Rt, Gt, Bt. As a result, text characters are superimposed and displayed on the CRT screen at required locations on the graphic image. Here, when the low level black display signal Sb is input to the AND gates 4r, 4g, 4b, each text RGB signal Rt, Gt, Bt is input to the AND gate 4r,
Blocked by 4g and 4b, RGB data selector 1
In this case, the text RGB signals Rt, Gt, and Bt are input at low level. On the other hand, the text
Since the RGB signals Rt, Gt, and Bt are also input to the NOR gate 3, a low-level selection signal is output from the NOR gate 3, and this selection signal allows
Text RGB signal Rt with RGB data selector 1,
Gt, Bt is selected and the output is changed from the graphic RGB signal Rg, Gg, Bg to the text RGB signal Rt, Gt,
Switch to Bt. At this time, as mentioned above,
Since each text RGB signal Rt, Gt, Bt is at low level, this low level text
RGB signals Rt, Gt, Bt will be sent from RGB data selector 1 to the CRT, and with these low level text RGB signals Rt, Gt, Bt,
On the CRT screen, black text characters will be superimposed and displayed at the required locations of the graphic image. As mentioned above, the black display signal Sb is generated and output according to the instructions of the CPU, and the method of generation and the configuration of the generation circuit are not particularly limited, but an embodiment embodying the generation circuit will be described below. In each embodiment, the same components as in the embodiment shown in FIG. 1 are designated by the same reference numerals. (B) Second Embodiment FIG. 2 is a block diagram of a second embodiment in which a latch circuit and a black display data selector generate and output a black display signal Sb. In addition to the example components, there is also a latch circuit 5 that latches the data signal from the CPU, the output of the latch circuit 5, and the text RGB signals Rt, Gt,
It has a black display data selector 6 that introduces Bt. The black display data selector 6 receives data signals D0 to D7 input through the latch circuit 5.
A black display signal Sb is output from the output terminal W in response to the text RGB signals Rt, Gt, and Bt.
When the value of the data signals D0 to D7 is "0", the black display signal Sb is not output, and the data signals D0 to D7 are
When the value of is "1", a black display signal Sb is output.
The correspondence relationship between the input signal and output signal is shown in attached table 1.
As shown in the table. As is clear from Table 1, by supplying the required data signals D0 to D7 to the data selector 6 in correspondence with the text RGB signals Rt, Gt, Bt input to the data selector 6 for black display, Text characters of any color are converted to black and displayed. A data bus of the CPU is connected to the input terminal of the latch circuit 5, and a data signal from the data bus is latched into the latch circuit 5 according to a command from the CPU.

[Table] (C) Third embodiment Figure 3 is a block diagram of a third embodiment in which a black display signal Sb is generated and outputted by a memory and a data selector for black display. In addition to the components of the first embodiment, there is also a memory 7 in which writing/reading is performed by addressing the CPU.
and the data signal D read out from the memory 7.
0 to 7 and a black display data selector 6 for introducing text RGB signals Rt, Gt, Bt.
The black display data selector 6 receives the input data signal D0 as in the second embodiment.
~7 and the text RGB signals Rt, Gt, Bt, the black display signal Sb is output from the output terminal W, and the correspondence relationship between the input signal and output signal is as shown in Appendix Table 1. It's the same. A data output terminal of a memory 7 is connected to the input terminal of the black display data selector 6, and the data output terminal of the memory 7 is also connected to a data bus of the CPU. In addition to being able to write arbitrary data to the memory 7, the CPU can also read the contents of the memory 7.
You can see which color text characters are converted to black. (D) Fourth Embodiment FIG. 4 is a block diagram of a fourth embodiment in which a latch circuit and a comparator generate and output a black display signal Sb, and shows the constituent parts of the first embodiment shown in FIG. In addition, it has a latch circuit 8 that latches a data signal from the CPU, and a comparator 9 that introduces the output of the latch circuit 8 and text RGB signals Rt, Gt, and Bt and compares them. The comparator 9 outputs the output of the latch circuit 8 and the text.
When the RGB signals Rt, Gt, and Bt match, a black display signal Sb is output. This comparator 9 is 4
In the bit comparator, one input terminal A1-4
In addition to the text RGB signal, a constant high level signal is input to the input terminals B1 to B4, and in addition to the data signals corresponding to the text RGB signals Rt, Gt, and Bt, the black bit for black display is input to the other input terminals B1 to B4. input.

【table】

[Table] This black bit is a high level and active signal. The correspondence between the input signal and the output signal of the comparator 9 is as shown in Table 2 of the attached table. The latch circuit 8 is connected to the data bus of the CPU, and latches the data signal from the CPU at a predetermined timing. <Effects of the Invention> As described above, according to the present invention, the text RGB signal input to the black conversion gate circuit is cut off and becomes low level by the black display signal generated and output by the CPU instruction, and this becomes the RGB Since it is sent to the CRT through the data selector, this low-level text RGB signal causes black text characters to be displayed on the CRT screen, superimposed at desired locations on the graphic image. Therefore, the range of expression forms for superimposition has expanded, and when both the graphic image and the text character are bright colors, displaying the text character in black makes the superimposed display screen easier to see. be able to.

[Brief explanation of drawings]

Figure 1 is a block diagram of the CRT display system of the present invention.
Figure 2 is a block diagram of the second embodiment, Figure 3 is the block diagram of the third embodiment.
FIG. 4 is a block diagram of the fourth embodiment, and FIG. 5 is a block diagram of a conventional CRT display system. 1...RGB data selector, 2...palette circuit,
3...Selection gate circuit (NOR gate), 4 (4r,
4g, 4b)...Black conversion gate circuit (AND gate), 5...Latch circuit, 6...Data selector for black display, 7...Memory, 8...Latch circuit, 9...Comparator.

Claims (1)

[Claims] 1. Graphic RGB signal and text RGB
Introduce a signal and select either one by the selection signal.
An RGB data selector that selects an RGB signal and outputs it to the CRT, and a text RGB signal that is introduced when any text RGB signal is input.
A selection gate circuit is provided for outputting a selection signal to an RGB data selector, and a selection gate circuit is provided for each text RGB signal to introduce each text RGB signal and a black display signal, and when a black display signal is not input, each text RGB signal is input to the RGB data selector. A computer system CRT display system equipped with three black conversion gate circuits that cut off the text RGB signal when a black display signal sent to the data selector is input. 2. The CRT display method of the computer system according to claim 1, further comprising a latch circuit that latches a data signal from the CPU, and a data selector for black display that introduces the output of the latch circuit and a text RGB signal. A CRT display method for a computer system, wherein the black display signal is generated and outputted by the black display data selector in correspondence with a data signal and a text RGB signal. 3. In the CRT display method of the computer system according to claim 1, a memory in which writing/reading is performed according to address designation of the CPU, and a data signal and a text RGB signal read from the memory are introduced. a data selector for black display, wherein the black display signal is generated and output by the data selector for black display in correspondence with the data signal and the text RGB signal.
CRT display method. 4. In the CRT display system of a computer system according to claim 1, a latch circuit that latches a data signal from a CPU, and a comparator that introduces the output of the latch circuit and a text RGB signal and compares the two. and the black display signal is the output of the latch circuit and the text
A CRT display method for a computer system, characterized in that the comparator outputs an output when the RGB signal matches the RGB signal.