JPH05346774A - Method for reading character generator - Google Patents

Abstract

PURPOSE:To eliminate the flicker of a display picture at the time of reading a character font and comparison-inspecting and to prevent the lowering of processing speed in a reading method when by a central processing unit(CPU), the character font in a character generator(CG) is read and comparison-inspected while displaying the picture constituted of a character. CONSTITUTION:This method is a character display circuit in a personal computer and a word processor, etc., and in the character display circuit provided with a first display control part(CRTC1) 3 displaying a document, etc., made by the CPU 1, a display control mechanism consisting of a character code video memory(CVRAM) and the CG1 (7), and the display control mechanism consisting of the CG2 (8) reading the specific character font and processing it and writing and displaying a bit map image in a graphic video memory(GVRAM) 26 and a second display control part(CRTC2) 25, circuits 11, 12, (1), (2) switching the content of the display exclusive CG1 (7) and the content of the reading and processing CG2 (8) selectively and reading it, is provided, and this circuit is constituted so that by the CPU 1, the contentents of the CG1 (7) and the CG2 (8) are compared and inspected independent of the display of the document.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a personal computer, a word processor, etc., a central processing unit (CPU) reads a character font in a character generator (CG) while displaying a screen composed of characters such as a document, The present invention relates to a device capable of being processed into italic characters, Gothic characters, enlarged characters, reduced characters, etc., and writing and displaying the above document in a graphic video memory (GVRAM) in a bitmap format.

In recent years, document processing devices such as personal computers and word processors have been required to have sophisticated user interface functions, and high-performance document processing devices have been provided. Existing character fonts are one of the functions. The function to process is necessary. This is a method for converting character fonts in a character generator (CG) (character generator, abbreviated below) to a central processing unit (C
It can be realized by reading and processing by (PU).

At this time, since the displayed document may flicker, a character display control circuit that does not cause the flicker is required. Of course, it is possible to prepare various character fonts in the character generator (CG) from the beginning, but with this, the capacity of the character generator (CG) becomes enormous, so only standard character fonts are prepared. If necessary, the central processing unit (CPU) must process and display.

[0004]

2. Description of the Related Art FIGS. 2 and 3 are diagrams for explaining a conventional character display circuit, showing a circuit portion for displaying a created document on a CRT display in a document processing device such as a personal computer or a word processor. Is.

First, in FIG. 2, a central processing unit (CPU)
After creating a document in the main storage device 2, 1 writes in the character code video memory (CVRAM) 4 and activates the first display control unit (CRTC1) 3.

The first display control unit (CRTC1) 3 accesses the character code video memory (CVRAM) 4,
The character code of each character is read in sequence, the first character generator (CG1) 7 is accessed with the read character code, and the raster address for the corresponding character font is given to the dot for one raster of the corresponding character. By taking out the data, performing parallel / serial conversion to the shift register 12 to generate a video signal, and outputting the horizontal and vertical synchronizing signals 24, the character code video memory (CRT) 13 can be displayed on the CRT display (CRT) 13.
Display the documents stored in (VRAM) 4.

When the first display controller (CRTC1) 3 is displaying a document, the central processing unit (CPU) 1 accesses the first character generator (CG1) 7 to display a predetermined character. After reading, for example, processing into italic characters, Gothic characters, etc., and writing to the graphic video memory (GVRAM) 26 in the form of bitmap, the display control by the first display control section 3 is suppressed, Second display controller (CRTC
2) When 25 is started, the second display control unit (CRTC2) 25
Reads bit information of the graphic video memory (GVRAM) 26 and inputs the bit information to the shift register 12 to convert the document into the processed characters,
It is displayed on the CRT display (CRT) 13.

Of course, at this time, only specific characters on the character code video memory (CVRAM) 4 are processed,
Write in a bitmap format to the graphic video memory (GVRAM) 26 corresponding to the display content of the character code video memory (CVRAM) 4 and superimpose on the display content of the character code video memory (CVRAM) 4 (specifically, It may be overwritten and displayed.

While displaying such a conventional screen composed of characters, the central processing unit (CPU) 1
In the character display device capable of reading and processing the character font in the character generator (CG1) 7 of 1), 1) as shown in FIG.
G) has only one set, and the display-only address (character code, raster address) output from the first display control unit (CRTC1) 3 and the central processing unit (CPU) 1 read and output for processing. Character code address decoder (ADEC) 6
The method of accessing the first character generator (CG1) by switching the character address and raster address decoded and output by the selector (SEL1) 10 and selector (SEL2) 9.

2) As shown in FIG. 3, the first display-dedicated first character generator (CG1) 7 accessed by the first display control unit (CRTC1) 3 and the central processing unit (CPU) 1 have the above address. A method that has two sets of character generators, a second character generator (CG2) 8 for reading and processing through a decoder (ADEC) 6 and making them independently accessible.

There was

[0012]

Generally, the central processing unit (C
The character generator access for reading and processing by (PU) 1 is performed asynchronously with the display-only access by the first display control unit (CRTC) 3.

Therefore, in the above method 1), when the access for reading and processing from the central processing unit (CPU) 1 and the access from the first display control unit (CRTC1) 3 overlap, the central processing unit If the access from the processing unit (CPU) 1 is prioritized, the access address to the first character generator (CG1) 7 is switched, which causes a problem of flickering on the screen.

On the contrary, the first display control unit (CRTC) 3
If the priority is given to the access for display from, the weight must be applied to the central processing unit (CPU) 1, which causes a problem that the processing speed of the central processing unit (CPU) 1 is reduced.

On the other hand, in the method 2), the central processing unit (CP
Since U) 1 and the first display control unit (CRTC) 3 can independently access different character generators (CG1, CG2) 7, 8 respectively, the problem as in 1) does not occur.

However, the character generator (C
Since there are 2 sets of G), 2 sets of character generator (CG
(1, CG2) 7,8 contents match (obstruction during manufacturing,
The CPU (CPU) 1 reads the character font of the first character generator (CG1) 7 accessed by the first display control unit (CRTC1) 3 above. Since it is not possible to directly compare the font data read by the central processing unit (CPU) 1, the CRT display
There is no choice but to indirectly compare the font data displayed on the screen of 13 with the character font data read by the central processing unit (CPU) 1 for processing and written in the graphic video memory (GVRAM) 15 above. It was

In view of the above-mentioned conventional drawbacks, the present invention provides a character generator (CG) for display only, reading, and processing.
By having two sets of the character generator (CG), flicker on the screen at the time of reading the character generator (CG) and a decrease in the processing speed of the central processing unit (CPU) are prevented, and at the same time, the central processing unit (C
It is an object of the present invention to provide a reading method of a character generator that allows a PU to easily compare and inspect the contents of two sets of character generators (CG1, CG2).

[0018]

FIG. 1 is a diagram showing an embodiment of the present invention. The above problems are solved by the character display circuit configured as follows.

A character display circuit for a personal computer, a word processor, etc., which includes a first display control unit 3 for displaying a document etc. created by the central processing unit 1, a character code video memory 4, and a first character. To display and process a specific character font by the display control mechanism consisting of the generator 7 and the central processing unit 1 and write the bitmap image in the graphic video memory 26 different from the character code video memory 4 and display it. In the character display circuit having the display control mechanism including the second character generator 8 and the second display control unit 25, the contents of the first character generator 7 dedicated to the display and the above-mentioned reading and processing Circuit for selectively switching and reading the contents of the second character generator 8 of
1, the contents of the first character generator 7 and the second character generator 8 are provided independently of the display of the document by the reading circuit 22, 22, 11.
Is configured to be selectively read.

[0020]

In the present invention, the first display control unit (CRTC1) for displaying a document created by the central processing unit (CPU) 1
3, a character code video memory (CVRAM) 4, a display control mechanism composed of a first character generator (CG1) 7, and a central character processing unit (CPU) 1 for reading and processing a specific character font, The second character generator (CG2) 8 for writing and displaying the bit map image in the graphic video memory (GVRAM) 26 different from the character code video memory (CVRAM) 4 and the second
In the character display circuit provided with the display control mechanism including the display control unit 25 and the contents of the first character generator (CG1) 7 dedicated to the display, and the second character generator (CG2 8) and the contents of 8 are selectively switched and read out.

Therefore, normally, the first display control unit (CRTC
1) Under the control of 3, character code video memory (CV
RAM) 4 Based on the character code of the document stored in the document, the first character generator (CG1) 7 is accessed to display the document on the CRT display (CRT) 13, and the central processing unit (CPU) 1 accesses the second character generator (CG2) 8, reads the character font, processes it, and outputs the character code video memory (C
VRAM) 4 different graphics video memory (GVRAM) 26
Since a bitmap image can be written in, the second character generator (CG2) 8 is accessed,
The above display is not disturbed when the character font is read and processed.

Then, the first character generator
(CG1) 7 contents and the second character generator (C
G2) When comparing and comparing with the contents of 8, for example, at the time of initialization, first, the character font of the first character generator (CG2) 7 for reading and processing is changed to the main memory (MM) 2 Read it out to the selection controller (S
Address decoder (ADEC) accessed by the central processing unit (CPU) 1 by sending the selection signal 20 from EL CTL) 5.
Select the address (character address, raster address) from 6 and select the first character generator (CG
1) Select the character font from 7 and select it (SEL3)
By reading to the main memory (MM) 2 via 11, the character font of the first character generator (CG2) 7 and the character font of the second character generator (CG2) 8 can be displayed without disturbing the display. You can compare with fonts. Further, under the control of the first display control unit (CRTC1) 3, while the document in the character code video memory (CVRAM) 4 is being displayed, the selection signal 20 is sent from the selection control unit (SEL CTL) 5. When sent, the address from the central processing unit (CPU) 1 to the address decoder (ADEC) 6 is selected, and the character font from the first character generator (CG1) 7 is selected and collated. Image distortion may occur, but since such an opportunity rarely occurs, it does not hinder the present invention.

Therefore, by having two sets of character generators (CG) for display, reading, and processing, and selectively switching and reading, the first character generator (CG1) is read, Read the character generator (CG) on the screen when it is displayed,
There is an effect that the flicker at the time of processing can be eliminated and the contents of the two character generators (CG) can be inspected while suppressing the decrease in the processing speed of the central processing unit (CPU).

[0024]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 described above is a diagram showing an embodiment of the present invention. In the present invention, a character display circuit for a personal computer, a word processor, etc., a first display control unit (CRTC1) 3 for displaying a document etc. created by a central processing unit (CPU) 1, and a character code video A display control mechanism consisting of a memory (CVRAM) 4 and a first character generator (CG1) 7,
A specific character font is read and processed by the central processing unit (CPU) 1, and a graphic video memory (GVRA) different from the character code video memory (CVRAM) 4 is processed.
M) A character display circuit provided with a second character generator (CG2) 8 for writing and displaying a bitmap image on the 26 and a second display control unit (CRTC2) 25, and Contents of the character generator (CG1) 7 and the second character generator (CG) for reading and processing.
2) A circuit for selectively reading the contents of 8 and 8 and 22, 11 are provided, independently of the display of the above document,
The contents of the first character generator (CG1) 7 and the second character generator (CG2) 8 are selectively
The means for switching and reading is the means necessary for carrying out the present invention. The same reference numerals denote the same objects throughout the drawings.

The configuration and operation of the character display circuit of the present invention will be described below with reference to FIG. First, FIG. 1 is a diagram showing an embodiment of the present invention. In FIG. 1, 1 is a central processing unit (CPU), which is a character code video memory
In (CVRAM) 4, write the character code of the document created in advance and stored in the main memory (MM) 2, or
To issue a command to the display control unit (CRTC1) 3 and read the character font data from the character generators (CG1) 7, (CG2) 8; 2 is the main memory (MM) and the central processing unit (CPU). ) 1 stores programs and data to be executed, 3 is the first display controller (CRTC)
1) and sync signal (horizontal sync signal, vertical sync signal) 2
4 is generated (in a strict expression, it means that a sync signal is placed on the signal line 24. The same applies hereinafter), and addresses 16 and 17 for scanning the above character code video memory (CVRAM) 4 are generated. In addition, 4 is the above-mentioned character code video memory (CVRAM) that stores the character code of the document displayed on the screen, and 5 is the selection control section ( SEL CTL), which controls the entire switching of the character generators (CG1) 7, (CG2) 8 for display only, reading, and processing, and has a switching specification register (not shown) inside. In response to this, the selector selection signal 20 is generated, or the character generator (CG1) 7, (CG2) 8 characters are sent to the central processing unit (CPU) 1 via an internal gated buffer (not shown). Font day Which sends, 6 is an address decoder (ADEC),
The character code from the central processing unit (CPU) 1 is decoded to generate the aforementioned character access to the character generator (CG1) 7, (CG2) 8 and raster address 19, 7 and 8 are the character generator (CG1 ), (CG
2), which generates a bitmap font corresponding to the character code, 9,10,11 are selectors (SEL1 to SEL3)
Is for switching the display-only, read-out, and processing addresses according to the selector selection signal 20 described above, and 12 is a shift register for converting the data generated by the character generator (CG1) 7 into parallel-to-serial conversion. Then the video signal
23 is a CRT display which is a raster scan type which displays characters on the screen by using a video signal 23 and a synchronizing signal 24.

In the normal case, the selection control unit (SEL CTL) 5 is
A selection signal 20 is sent to the selector (SEL2) 9, (SEL1) 10 to select the display-only address (raster address, character address) 17, 18, and the second character generator (CG2) is sent to the selector (SEL3) 11. ) Send the select signal 20 to select 8 data 22.

In this state, the character display circuit shown in FIG.
It works the same as the character display method 2) explained in. That is,
When displaying characters, the first display controller (CRTC1) 3
Sends the display address 16 and scans the character code video memory (CVRAM) 4, and in response, the character code of each character of the document output by the character code video memory (CVRAM) 4 is addressed by the address decoder (ADEC). Character address 18 decoded in 6 and raster address
17 by the first character generator (CG1) 7
Outputs character fonts in parallel, shift register 1
The document is displayed on the CRT display 13 after being parallel-to-serial converted in 2.

When the central processing unit (CPU) 1 accesses the second character generator (CG2) 8, the character code accessed by the central processing unit (CPU) 1 and the address corresponding to the raster are output. , Address decoder (ADEC) 6
Decodes the address and generates an address 19 for access to the second character generator (CG2) 8.

With this address, the second character generator (CG2) 8 outputs the corresponding character font data, which is read into the central processing unit (CPU) 1 via the selection control unit (SEL CTL) 5. Be done.

Since these two accesses can be made independently,
Even if access is repeated, the problem of flickering the display screen does not occur. Next, the first character generator (CG1) 7 and the second character generator (CG1)
2) When comparing the contents of 8, first, the central processing unit (CPU)
For 1, the contents of the second character generator (CG2) 8 are read by the above method and stored in the main memory (MM) 2. Next, the selection control unit (SEL CTL) 5 operates the selector (S
EL2) 9, Selector (SEL1) 10 is sent a selection signal 20 to select address 19 for access from the central processing unit (CPU), and selector (SEL3) 11 is sent to the first character generator (CG1). ) Send the select signal 20 to select 7 data.

To access the first character generator (CG1) 7, the central processing unit (CPU) 1 outputs the code of the character accessed by the central processing unit (CPU) 1 and the address corresponding to the raster. An address decoder (ADEC) 6 decodes the address and generates an address for accessing the first character generator (CG1). With this address, the first character generator (CG
1) 7 outputs character font data, which is read by the central processing unit (CPU) 1 via the selection control unit (SEL CTL) 5.

The central processing unit (CPU) 1 compares this data with the data of the second character generator (CG2) 8 on the main memory (MM) 2. In this state,
Since the character display circuit is in the same state as in the method 1) described in FIG. 2, there is a display request from the first display control unit (CRTC1) 3 during access from the central processing unit (CPU) 1. If you do, there will be problems. In this case, the selection control unit (SEL
If the CTL) 5 performs arbitration such that the access right is not passed to the first display control unit (CRTC1) 3 until the access from the central processing unit (CPU) 1, the screen flickers. There is no problem because the generators (CG1, CG2) are rarely compared.

In particular, the character generator (CG1, CG
If the comparison of 2) is performed at the time of initialization of the character display circuit, there will be no further problem. As described above, the present invention is a character display circuit in a personal computer, a word processor, etc., and includes a first display control unit (CRTC1) 3 for displaying a document created by the central processing unit (CPU) 1, A display control mechanism including a character code video memory (CVRAM) 4 and a first character generator (CG1) 7, and the central processing unit
The second character for reading and displaying a specific character font by (CPU) 1, processing it, and writing and displaying a bitmap image in graphic video memory (GVRAM) 26 different from the above character code video memory (CVRAM) 4. In the character display circuit provided with the generator (CG2) 8 and the second display control unit (CRTC2) 25, the contents of the display-dedicated first character generator (CG1) 7 and the reading and processing first character The contents of 2 character generator (CG2) 8
The first character generator (CG1) 7 and the second character generator are provided independently of the above-mentioned document display by selectively switching and reading circuits, 22 and 11.
(CG2) 8 contents and are selectively switched and read,
The feature is that the central processing unit (CPU) can be used for collation.

[0034]

As described above, according to the present invention, a character generator for display only, reading, and processing is provided.
By having two sets of (CG) and allowing the contents of each to be selectively switched and read, a character font can be read from the character generator (CG) while it is being displayed. Flickering of the display screen when reading and processing, and central processing unit (CPU)
It is possible to prevent the processing speed from decreasing and at the same time easily inspect the contents of the two sets of character generators (CG).
It has a great effect if it greatly contributes to the performance improvement of a word processor or the like.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of the present invention.

FIG. 2 is a diagram (part 1) illustrating a conventional display control circuit.

FIG. 3 is a diagram (part 2) explaining a conventional display control circuit.

[Explanation of symbols]

1 Central processing unit (CPU) 2 Main memory (MM) 3 First display control unit (CRTC1) 4 Character code video memory (CVRAM) 5 Selection control unit (SEL CTL) 6 Address decoder (ADEC) 7 First character Generator (CG1) 8 Second character generator (CG2) 9 Selector (SEL2) 10 Selector (S
EL1) 11 Selector (SEL3) 12 Shift register 13 CRT display (CRT) 20 Select signal, or selector select signal 21 First character generator (CG1) read data 23 Video signal 24 Sync signal 25 Second display control section (CRTC2) 26 Graphic video memory (GVRAM) Raster address for 1st character generator (CG1) Read data of 1st character generator (CG1)

Claims (1)

[Claims] 1. A character display circuit for a personal computer, a word processor or the like, which is a first for displaying a document or the like created by the central processing unit (1).
Display controller (3) and character code video memory
(4), a display control mechanism consisting of the first character generator (7), and a specific character font is read out by the central processing unit (1), processed, and separated from the character code video memory (4). Graphics video memory (2
The second for writing and displaying the bitmap image in 6)
Character generator (8) and the second display controller (2
In a character display circuit provided with a display control mechanism consisting of 5), the contents of the first character generator (7) dedicated to the display and the contents of the second character generator (8) for reading and processing are added. Is provided with a circuit (, 22 ,, 11) for selectively switching and reading, and the reading circuit (, 22 ,, 11) is provided independently of the display of the above document.
, 11), the first character generator (7)
And a content of the second character generator (8) are selectively read out.