JPH05265425A - Text screen graphic controller - Google Patents

Abstract

PURPOSE:To reduce cost, increase reliability, and save a space and to reduce the trouble of designing by providing a text screen plotting function and an output function for a CRT by one LSI. CONSTITUTION:A text screen controller include a text, RAM 8 and an attribute RAM 7 wherein a character code and an attribute outputted from a CPU 2 are written. Further, a character generator control part 12 reads the contents of the text, RAM 8 out and sends the contents out to a character generator 11. The obtained image data are converted by an image arithmetic part 10 to obtain an image signal synchronized with a horizontal and a vertical synchronizing signal. The image signal is converted by a CRT driver 13 into an RGB signal, which is outputted to the CRT 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a text screen graphic controller, and more particularly to an LSI for constructing an H / W for a text screen of a computer system.

[0002]

2. Description of the Related Art A conventional text screen controller, especially a graphic display controller, has an external R
It has only the function of writing data to the AM, the function of generating a synchronization signal, and the function of generating a control signal to an external LSI according to the image mode. For example, NEC Technical Report V
oL. 43 No8 / 1990 N5200 series hardware is also introduced.

FIG. 3 is a block diagram of a text screen controller showing such a conventional example. As shown in FIG. 3, the conventional H / W structure of the text screen drawing unit 19 is composed of various RAMs and a control unit. The CPU 2 is the graphic display controller 1 of the text drawing unit 19.
The drawing mode is set for 5, and then the character code and the attribute are written into the text RAM 8 and the attribute RAM 7 via the command control unit 5 and the text RAM control unit 21, respectively. Text R
The character code written in the AM 8 is read by the character generator control unit 12 and sent to the character generator 11. Since the character generator 11 outputs the image data to the attribute synthesizing unit 22 based on the received character code, the attribute synthesizing unit 22 converts the image data into image output data for a text screen according to the attribute from the attribute RAM 7. The image output data of the text screen is mixed with the data output from the graphic screen drawing unit 20 in the text screen / graphic screen combining unit 18,
The RGB signals are output to the CRT (not shown).

[0004]

In the conventional text screen controller described above, the H / W for constructing the text screen of the CRT must be individually designed for each system, and an individual LSI is required. Not only that, there is a drawback that it takes a lot of man-hours for the circuit designer and is troublesome.

An object of the present invention is to provide a text screen graphic controller that contributes to cost reduction, high reliability, and space saving, and can eliminate the troublesome design.

[0006]

A text screen graphic controller according to the present invention includes a text RAM and an attribute RAM, a command controller and a DMA controller for controlling writing of data to the two RAMs, and a character image. A character generator that outputs data, a character generator control unit that outputs the data written in the text RAM to the character generator, and an image calculation unit that converts the image of the character according to the contents of the attributor RAM. , A sync signal generator for generating sync signals for RGB signals, and C for sync signal and image signal.
And a CRT driver for converting to an electric level for outputting to RT.

[0007]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a block diagram of a text screen graphic controller showing an embodiment of the present invention. Figure 1
As shown in FIG. 5, the text screen controller 1 in this embodiment represents a function of the text screen drawing function which is shared by the respective systems. In addition, CPU2 is I /
After setting the I / O memory switching signal terminal T4 to "1" via the O logic circuit 3, the size of the text screen and the cursor output mode are output to the command control unit 5.
Next, the I / O memory switching signal terminal T4 is set to "0", and the character code and the attribute are passed to the text RAM 8 and the attribute RAM 7, respectively. At this time, the chip select signal terminal T1, the read signal terminal T2, and the write signal terminal T3 are used as signal terminals for controlling data access as in a general-purpose SRAM. Incidentally, these character codes and attributes can also be supplied from the command control section 5 by setting the I / O memory switching signal terminal T4 to "0". When switching the text screen at high speed, the DMA controller 6 rewrites the contents of the text RAM 8 and the attribute RAM 7 without passing through the CPU 2. Further, the character generator control unit 12 reads the character code written in the text RAM 8 and sends it to the character generator control unit 11 or the Kanji character generator 14 provided outside the text screen controller 5, so that an image corresponding to the character code is obtained. Output data.

On the other hand, the image calculation unit 10 converts the output image data of the character based on the instructions of the attribute RAM 7 and the command control unit 5. Further, the image calculation unit 10 receives the synchronization signal from the synchronization signal generation unit 9 and outputs the image data converted according to the synchronization signal together with the synchronization signal. The sync signal and the image data are converted by the CRT driver 13 into RGB signal levels that can be input to the CRT. In this way, the text screen controller 1
Outputs the RGB signal and the synchronizing signal to the CRT 4.

FIG. 2 is a block diagram of a text screen graphic controller showing another embodiment of the present invention. As shown in FIG. 2, this embodiment has a function of drawing a text screen and a function of drawing a graphic screen.
Sends the images to be output to the CRT 4 to the text screen graphic controller 1 and the graphic controller 15 equipped with the Chinese character generator 14 in the form of character codes and commands, respectively. When the graphic display controller 15 writes the image data in the graphic VRAM 16, the shift register 17 sends the image data written in the graphic VRAM 16 to the text screen / graphic screen combining unit 18 bit by bit. As a result, the text screen / graphic screen combining unit 18 mixes the RGB signals from the text screen controller 1 with the image data from the shift register 17, and outputs the mixed signals to the CRT 4.

[0010]

As described above, the text screen graphic controller of the present invention realizes the drawing function of the text screen by a single LSI, thereby lowering the cost of a system having a CRT and increasing the reliability and saving the system. It has the effect of contributing to space. Further, the present invention has an effect that it is possible to eliminate the troublesomeness of designing an H / W for realizing a drawing function of a text screen for each system and reduce the number of design steps.

[Brief description of drawings]

FIG. 1 is a block diagram of a text screen graphic controller according to an embodiment of the present invention.

FIG. 2 is a block diagram of a text screen graphic controller according to another embodiment of the present invention.

FIG. 3 is a block diagram of a conventional text screen controller.

[Explanation of symbols]

 1 Text screen controller 2 CPU 3 I / O logic circuit 4 CRT 5 Command control unit 6 DMA controller 7 Attribute RAM 8 Text RAM 9 Sync signal generation unit 10 Image calculation unit 11 Character generator 12 Character generator control unit 13 CRT driver 14 Kanji character Generator 15 Graphic display controller 16 Graphic VRAM 17 Shift register 18 Text screen / Graphic screen synthesizer

Claims (1)

[Claims] 1. Text RAM and attribute R
AM, a command controller and a DMA controller that control writing of data to the two RAMs, a character generator that outputs character image data, and the character generator that writes the data written in the text RAM. A character generator control unit, an image calculation unit that converts the image of the character according to the contents of the attributor RAM, a synchronization signal generation unit that generates a synchronization signal for RGB signals, the synchronization signal and the image. A text screen graphic controller having a CRT driver for converting a signal into an electric level for outputting to a CRT.