JPS62244093A - Character display unit - 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] [Industrial Application Field] The present invention relates to a device for displaying characters on a CRT. ¥fK This relates to improvements to the character generator section that stores patterns of characters to be displayed.

[Conventional technology]

A conventional character display device of this type is comprised of a character generator 13.2 (4F non-replaceable mask ROM) that stores patterns of characters to be displayed, as shown in FIG.

[Problem that the invention seeks to solve]

The conventional character display device described above uses a character display device that stores character patterns to be displayed on a CRT.
Generator 13 is a mask ROM that cannot be rewritten.
Since it was composed of A drawback is that a large number of small-capacity character generator ROMs must be prepared for each ROM or display mode.

[Means for solving problems]

The character display device of the present invention has a structure in which a part of the conventional character generator mask ROM section is replaced with a RAM in order to temporarily store various character patterns that are rarely used.

(Example〕 Next, the present invention will be explained with reference to the drawings.

FIG. 1 shows a configuration according to an embodiment of the present invention, where l is an oscillation circuit, 2 is a timing signal generation circuit,
3 is a video RAM, 4 is a microcomputer, 5 is a character cost generator ROM, 6 is a character generator RAM, 7u output shift register, 8 is a CR
It is T.

The timing signal generation circuit 2 counts the horizontal synchronization signals 102 and outputs a row selection signal 105.

Note that the row selection signal 105 is the vertical synchronization signal 101 of CRTs.
reset by . The timing signal generation circuit 2 also counts the dot clock 103 output from the oscillation circuit 1 and outputs a digit selection signal 104. Digit selection signal 104
is reset by the horizontal synchronization signal 102. Here, a row is a character string in the horizontal direction on the display surface of the CRT 8, and a digit is a character string in the vertical direction on the display surface. The video RAM 3 generates a character code signal 106 corresponding to the row and digit selected by the row selection signal 105, digit selection signal 104, and K. Note that the character code stored in the video RAM 3 is rewritten with character code data 107 given from the micro combinator 4 at any time in accordance with the display contents. Character generator ROM 5 receives character code signal 106 and generates character pattern signal 109. The output shift register 7 reads the character pattern signal 109 and shifts it.
In synchronization with the dot clock 103 inputted as a clock, a character output signal 111 is output, and the character being input is displayed on the CRT 3.

In this embodiment, a character generator RAM 5 is provided so that the character pattern can be rewritten at any time. This character generator RAM receives the character pattern data 108 directly from the microcombi 4, rewrites the contents, and receives the character code signal 108 sent from the video RAM 3.
6, a character pattern signal 110 is output. In addition, this character generator RAM6 is
It is used for temporary storage of characters and patterns that are used infrequently, and is rewritten by the micro combinator 4 at any time in accordance with the display contents.

〔Effect of the invention〕

As explained above, the present invention has the advantage of partially changing the character generator section, which could not be rewritten because it was conventionally configured with a mask ROM, to a RAM configuration.
It becomes possible to display many types of gearactor φ patterns with a small number of character generator containers.

Frequently used characters and patterns such as numbers and alphabets are stored in the character generator ROM.
By storing infrequently used character patterns such as special symbols in the character generator RAM, the parts other than the micro combinator and CRT can be
When converting to C, it not only helps in reducing the size of the chip, but also
The problem of having to change the character generator ROM@1st-mask in accordance with the user's request is also eliminated.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is a block diagram showing a conventional example. 1.9...Oscillation circuit, 2.10...Timing signal generation circuit, 3,11...Video R
AM, 4.12...Micro Combiator,
5, 13...Character generator ROM
, 5... Character generator RAM 17
, 14... Output shift register, 8, 15...
・・・・・・CRT0 Agent Patent Attorney Uchihara E “::1.1-1
・〕)＼5.゛

Claims (1)

[Claims] A video RAM that stores character code signals to be displayed on a CRT display, a character generator that generates character pattern signals according to the character code signals, a shift register that serially outputs character pattern signals, and these video RAMs. ,
A character display device consisting of a timing signal generation circuit that controls an output shift register in synchronization with a vertical synchronization signal and a horizontal synchronization signal, and a microcomputer that controls the contents of displayed characters, which was conventionally constructed with a non-rewritable mask ROM. A character display device characterized by converting a part of a character generator into RAM and displaying a wide variety of characters (patterns) with a small capacity.