JPS59116688A - Image display - Google Patents

Abstract

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

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an image display device for displaying input signals on a CRT (cathode ray tube).

Generally, this type of image display device uses a character generator (hereinafter referred to as CG) to convert the code corresponding to each character stored in the video RAM into a dot pattern for display on a CRT. Characters for which corresponding dot patterns are not stored cannot be displayed on the CRT.

Therefore, conventionally, to solve this problem, RAM format CG
A method is used in which a dot pattern constituting a desired character is newly written on this CG.

However, with this method, even characters that are composed of a combination of characters that can be conventionally displayed on a CRT, that is, composite characters, must be newly written to the CG, which reduces the capacity of the CG and makes them unnecessary. Moreover, it was troublesome to write the dora 1 pattern constituting this composite character onto CG.

SUMMARY OF THE INVENTION An object of the present invention is to improve the above-mentioned conventional drawbacks and to provide an image display device that can easily display even complex characters on a CRT.

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

The coat of the character 45 in the drawing and input from part 1 to keyboard 1 is the CPU (central processing unit) including the memory part.
The data is written to the address in the video RAMa addressed by the unit 2. Also, the multiplexer 4 uses the refresh address from the CRT controller 5 instead of the address from the 020 unit 2 to update the video RA.
When M3 is addressed, the ]-code stored at that address is sent to CG6. In the character indicated by the code sent to the CG 6, a portion of the height designated by the rask address from the CRT controller 5 is converted into a dora pattern, and further converted into a serial signal by the next parallel-serial conversion circuit 7. This serial signal is CRT8
The characters are displayed on the CRTS while being synchronized with vertical and horizontal synchronizing signals from the CRT controllers 1 to 5.

In the above configuration, next two characters rYJ "-"
The operation when displaying the composite character "¥" on the CRT 8 will be explained.

By operating a specific function key on keyboard 1 to section 1, specify the character to be selected by the next key operation or a compound character, then press the "Y" key and then press the "-" key. , and then complete the input of the compound character by operating the function keys. The 020 part 2 receives these signals and stores in its memory the individual characters that make up the compound character "\", namely rYJ and code 1 for "-", and the code for the compound character "\". The designated address of the video RAM 3 is stored so that the code of the composite character "\" is to be stored in the video RAM 3, and a code of "Y" is initially written.

Then, as before, the code stored in the video RAM 3 is output to the CG 6, converted to a driver pattern, and output to the next parallel-serial conversion circuit 7, where it is converted to a serial signal and then output to the CRT 8, where each character is Is displayed. At this time, the CRT controller 5
G l] by the vertical synchronizing signal output from CRT8
An interrupt is sent to the U unit 2, and the character ``Y'' written in place of the compound character ``\'' in the video RAM 3 is
Run a program that rewrites the code of "" to the character "-1". Then, when the scanning of one screen is completed and the scanning of the next screen is started, the CRT' controller 1~
The CPU unit 2 is again interrupted by the vertical synchronizing signal outputted from the ○-ra 5, and in the same manner as in the previous case, this time a program is executed to rewrite the code of the character "-" to the code of the character rYJ. in this way,
Every time a vertical synchronization signal is output, an interrupt is made to the 020 section 2, and the codes of the character rYJ and the character "-" are alternately rewritten at the address where the composite character "\" in the video RAM 5 is to be stored. charactor"
By quickly switching between the display of the character "Y" and the character "-" on the CRTB, the composite character "-" is visually displayed.
¥” will be displayed.

As described in detail above, when displaying a compound character on a CRT, the image display device according to the present invention only needs to input information on the individual characters that make up the compound character. Since there is no need to write dot patterns to the new 7J, there is no need to expand the CG capacity, and if the compound character is made up of characters whose dot patterns have been stored in the CG, it is easy to create a variety of compound characters. It is possible to display it on C and RT, and the effect is great.

[Brief explanation of drawings]

The figure is a block diagram of a portion related to the display of a CRT when this embodiment is used in a solutor 1-prosetter. In the figure, 1 is the keyboard section, 2 is the CPU section, 3 is the Hiteo RAM, 5 is the CRT controller, 6 is the CG18 is the C
RT is available. patent applicant

Claims (1)

[Scope of Claims] 1. A video RAM in which codes corresponding to characters to be displayed are stored, an address bus for addressing the video RAM from the CPU, and a refresh address bus for sequentially reading data from the video RAM. Displays a multiplexer that performs switching, a character generator that converts the code output from the video RAM into a dot pattern, a parallel-to-serial conversion circuit that converts the output of the character generator to a serial signal, and the output of the parallel-to-serial conversion circuit. A CRT to
C which generates the refresh address, the rask address to the character generator, and the vertical and horizontal synchronization signals;
In an image display device that is connected to an RT controller, when displaying a composite character composed of a combination of multiple characters, an interrupt is sent to the CPU in synchronization with the vertical synchronization signal, and an address corresponding to the composite character in the video RAM is sent. An image display device comprising means for sequentially rewriting each character constituting a composite character.