JPS6337382A - Display controller - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to the control of data displayed on a display device, and more particularly to a display control device that performs composite display of a graphic screen and a text screen.

Conventional technology Conventionally, this display control device synthesizes display data on a graphic screen and text character data, which is the output of a character generator based on text code instructions, by hardware using a simple off-circuit, etc., and displays the result. Alternatively, software reads text character data from a character generator and combines it with display data on a graphic screen for display.

However, when synthesized and displayed using hardware in this way, the text characters are displayed on the graphics screen, but if the colors of the graphics screen and the text screen are similar, the text characters are difficult to see. Furthermore, when synthesizing using software, it takes time to process text character data, reducing system efficiency.

Problems to be Solved by the Invention The purpose of the present invention is to solve the above-mentioned drawbacks, namely, that with conventional hardware-based compositing circuits, it is impossible to determine the boundary between characters and the screen, and with software-based compositing, processing takes a long time. It is an object of the present invention to provide a display control device that solves the problem of the above problems.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention provides a text video storage unit that holds codes of text characters, a character generator that holds fonts of text characters, and an output of the character generator. a text parallel/serial conversion register that holds and shifts text character data one dot at a time every video clock; a graphic video storage unit that holds display data of a graphic screen;
Parallel for graphics that holds the data in the graphic video memory and shifts it one dot at a time for each video clock.
A serial conversion register, a flip-flop that holds the final output data of the text parallel/serial conversion register, and two successive outputs of the text parallel/serial conversion register are used to send graphic video data or to convert text video data. A control circuit for controlling whether to send external data before or after the text characters or to send external data before and after the text characters in order to emphasize the text video data is adopted.

Operation Since the present invention is constructed as described above, the two successive outputs of the text parallel/serial conversion register enable the control circuit to display borders based on external signals before and after text characters.

Example Next, embodiments of the present invention will be described with reference to the drawings.

Referring to FIG. 1, which shows an embodiment of the present invention in a professional circuit diagram, the display control device of the present invention includes a graphic video storage section 1, a graphic parallel/serial conversion register 2, and a text video storage section. 3, character generator 4, text parallel/serial conversion register 5, and free.

A specific example of the control circuit 16 of this embodiment includes two NAND circuits 13 and 1.
4, five AND1 circuits 8 to 12, and one OR circuit 15.

Next, the operation of this embodiment will be explained. First, graphic dot data is represented by G, text characters are represented by C1, and external signal data is represented by E. Next, a logic table for the control circuit 16 is shown in Table 1.

Table 1 G Nigella Quick data C: Character (text font) E: External data Looking at this table 1, if there is a text character output at timing l1lfi+, C o ” 1, the text character C is output as is. and there are no text characters (::
If o=Q, make a counterfeit at the timing T0 of the round part and Co=
0 and C1 of T n+1, == o, outputs data G on the graphic screen, otherwise outputs external data E.
It can be seen that it outputs .

Next, the operation of the embodiment shown in FIG. 1 having this control circuit 16 will be explained.

First, graphic screen data is stored in a graphic video storage section 1, read out when displaying, and sent to a graphic parallel/serial conversion register 2.

Further, the text characters are sent to the text parallel/serial conversion register 5 through the character generator 4 which stores the character font according to the code sent from the text video storage section 3 which stores the text character codes.

When only the graphic screen is displayed, the output of the text parallel/serial conversion register 5 is suppressed, and G is selected as the video signal ratio cuff to the display device. Further, in the case of only a text screen, G is suppressed, and if border data E of text characters is suppressed, the character font itself of the character generator 4 is sent to the display device.

Next, when displaying a text screen on a graphics screen, if the output of the text screen is expected next (co=
0. For CI=1), external signal E is selected by gate 8 to mark the front edge of the text character. Further, if a text character font exists (Co=1), co is output as is to display the text character. Next, if there is no current text character font and there is no next one (co=
At 0°CI=O), check the flip-flop 6 that stores whether or not a character font existed one clock before the current time, and if there is a character font, flip-flop and professional are set. , external signal E to gate 9
is selected, the border after the text character is done, and if there is no character font, the gate 10 selects the graphic screen data G.

As described above, the front and back of the character font will be bordered by an external signal.
I know it will happen. Figure 2 is a specific example of overwriting text character 1 on the graphic screen.
A one-dot space is left between the text and C, and the left and right edges of the text characters are outlined to make the characters easier to read and emphasize. It is also possible to insert arbitrary data into the border area and freely frame it in any color.

In this embodiment, the border is one dot, but it can also be made into a two-dot border by using two stages of flip-flops and blocks and changing the control circuit appropriately. Further, although colors were not particularly explained in this embodiment, in the case of a three-color display such as a color cathode ray tube, three of these circuits may be provided. Further, the internal configuration of the control circuit may be other than that as long as it has the characteristics shown in the logic table in Table 1.

Effects of the Invention As explained above, according to the present invention, text characters on a graphic screen can be changed by checking the data before and after a text character font and selecting text character data, graphic data, or external data depending on the content. This has the effect of making it easier to see and emphasizing it.

[Brief explanation of the drawing]

FIG. 1 is a block circuit diagram of an embodiment of the present invention, and FIG. 2 is a concrete example of a screen image diagram of the present invention. l...Graphic video storage unit, 2...
・Parallel/serial conversion register for graphics, 3
−°. ...Text video storage unit, 4...Character generator, 5...--°Text parallel/serial conversion register, 6...Flip-flop, 7... Video signal output, 8 to 12...
AND circuit, 13.14...NAND circuit, 15
...OR circuit, 16...Control circuit, C
...Text character data, E...External data, G...Graphic video data.

Claims (1)

[Claims] A text video storage unit that holds text character codes, a character generator that holds text character fonts, and a parallel/serial converter for text that holds the output of this character generator and shifts text character data one dot at a time for each video clock. register and
a graphic video storage section that holds the display data of the graphic screen; a graphics parallel/serial conversion register that holds the data in the graphic video storage section and shifts it one dot at a time for each video clock; /In a display control device comprising a synthesis circuit that synthesizes output data of a serial conversion register and sends it to a display device as a video signal,
The synthesis circuit includes a flip-flop that holds the output data of the text parallel/serial conversion register and a control circuit, and the control circuit stores the output data of the text parallel/serial conversion register and its next stage shift. data, the output data of the graphic video parallel/serial conversion register, the output data of the flip-flop, and external signal data, and by the two output data of the text parallel/serial conversion register, 1. A display control device configured to output any one of graphic video data, text character data, and external signal data.