JPH027092A - Character display attribute controller - Google Patents

Abstract

PURPOSE:To reduce the disorder of a screen display by holding display attribute data which is read out of a display attribute storage means in a holding means and making the display according to character patterns retrieved in a display character display means and the display attribute data from the holding means. CONSTITUTION:A control means 101 selects the display attribute data from the display attribute storage means 102 by a selecting means 104 unless there is access to the display attribute storage means 102 and display character storage means 106. When there is the access, on the other hand, the display attribute data held in the means 103 are selected. Therefore, when a CPU 107 accesses the means 102, a display is made based upon the data held in the means 103 to reduce the disorder of the display on the display means 105.

Description

[Detailed description of the invention] 〔table of contents〕 overview Industrial applications Conventional technology Problems that the invention aims to solve Means to solve problems action Example ■, Correspondence between the example and Figure 1 ■, Structure of the example ■, Operation of the example (i) Operation in the displayed cycle (ii) Operation in CPU cycle ■Summary of examples ■Variation of 0 invention Effect of the invention 〔overview〕 Regarding a character display attribute control device for a character display device.

In a character display device that displays characters by a display means based on a character pattern retrieved from a display character storage means and display attribute data retrieved from a display attribute storage means, with the aim of reducing disturbances on a display screen, holding means for temporarily holding the display attribute data read from the display attribute storage means; selection means for selecting one of the display attribute data read from the display attribute storage means and the data held in the holding means; Display attribute storage means 2 Display character storage means by the central processing section, comprising a character storage means and a control means for controlling the selection operation of the selection means based on whether or not the central processing section accesses the display attribute storage means. When accessing, the display is performed based on the character pattern retrieved from the display character storage means and the display attribute data held in the holding means.

[Industrial application field]

The present invention relates to a character display attribute control device for a character display device, and more particularly to a character display attribute control device for controlling character display attributes that performs display based on character patterns and display attribute data stored in the character display device. It is related to the device.

[Conventional technology]

In character display devices (e.g. character displays) used in personal combiators and word processors, the displayed characters are displayed in reverse (reverse).
Display attributes are controlled, such as display or blinking.

Among these character display devices, storage type devices have a read/write memory (VRAM) for storing characters to be displayed and attributes of the characters for one screen, and a read-only memory for storing character patterns. (ROM
), and display is performed based on the data read from these memories.

FIG. 4 is an explanatory diagram of a conventional character display device.

Attribute that stores attribute data) I
RAM403 and character VR that stores character data
AM404 is accessed based on the display address generated by display controller 401.

This display address corresponds to the display position on the character display section 409, and is sequentially generated as the screen of the character display section 409 is scanned.

A character font is searched from the font ROM 405 based on the character data output from the character VRAM 404,
This character font is converted in the attribute control unit 406 based on the attribute data from the VRAM 403, and then converted to the character display unit 409.
is displayed.

The operation of each part is synchronized with a basic cycle independent of the CPU 410. For example, in a certain cycle, the character VR
The character data read from the AM 404 is passed to the phono/rlOM 405 in the next cycle, and the character font is searched. Furthermore, in the next cycle, this searched character font is passed to the attribute control unit 406.

On the other hand, CPU4 to attribute view) VRAM403
, when accessing the character VRAM 404, the access switching circuit 407 generates a CPU access signal for the basic cycle based on the CPU access request signal output by the CPU 410.

While this CPU access signal is input to the address switching circuit 402, the address switching circuit 402
Address requested by PU410 (CPU address)
is selected.

Therefore, the attribute VRAM403. Character ■) λA
M404 is accessed based on the CPU address.

In this way, one display cycle is passed to the CPU 410 for access, and the CPU 410 is transferred to the 71-rebut VRAM 4 via the data buffer 408.
03 and the letter VI'? Access AM404. Such a cycle is called a CPU cycle.

In CPU cycles, Attribute 1 - VRA
M403. The data in the data line and in of the character VRAM 404 is the data accessed by the CPU 410 (C
I'U data).

On the other hand, display controller 401. Phono I-R0M40
5. Attribute control section 406 and character display section 40
9 operates during the CPU cycle in the same way as in the display cycle.

-Font RO is activated by CPU data that appears in the data line.
The character font is read from M405, and the CPU that appears on the data line of VRAM403 (attribute)
The data is input to the attribute control unit 406 as attribute data.

These character fonts and attribute data are
Since the data is not at the display address specified by the display controller 401, there is a problem in that if these data are displayed as they are, the display on the character display section 409 will be distorted.

The present invention was created in view of the above points, and an object of the present invention is to provide a character display attribute control device that controls attribute data to reduce display disturbances on a character display. .

[Problem to be solved by the invention]
[Means for Solving the Problems] By the way, in the conventional method described above, cr It is a mechanical block diagram of AM404.

In the figure, in a character display device that displays characters by display means 105 based on a character pattern retrieved from display character storage means 106 and display attribute data retrieved from display attribute storage means 102, holding means 103 The display attribute data read from the attribute storage means 102 is temporarily held.

The selection means 104 selects either the display attribute data read out from the display attribute storage means 102 or the data held in the holding means 103.

The control means 101 controls the selection operation of the selection means 104 based on whether or not the central processing unit 107 accesses the display character storage means 106 and the display attribute storage means 102.

Therefore, as a whole, when the central processing unit 107 accesses the display attribute storage means 1021 and the display character storage means 106, the character pattern retrieved from the character display storage means 106 and the display attribute data held in the storage means 103 are The configuration is configured so that the display is performed based on the

[Operation] The control means 101 determines whether or not the central processing section 107 accesses the display attribute storage means +02 and the display character storage means 106.

The selection means 104 selects display attribute data from the display attribute storage means 102 when there is no access from the central processing unit 107 based on the determination result of the control means 101;
When the central processing unit 107 accesses the display attribute storage means 102 and the display character storage means 106, it selects the display attribute data held in the holding means 103.

In the present invention, when the central processing unit 107 is accessing the display attribute storage means 102, the display on the display means 105 is changed by performing the display based on the display attribute data held in the holding means 103. Disturbance can be reduced.

[Example] Hereinafter, an example of the present invention will be described in detail based on the drawings.

FIG. 2 shows the configuration of a character display device using a character display attribute control device according to an embodiment of the present invention.

Here, the correspondence between the embodiment of the present invention and FIG. 1 will be shown.

The control means 101 corresponds to the access switching circuit 207.

The display attribute storage means 102 corresponds to an attribute read/write memory (Vr?AM) 203.

The holding means 103 corresponds to the latch 221.

The selection means 104 corresponds to the selector 222.

The display means 105 corresponds to the character display section 209.

Display character storage means 106 corresponds to character VRAM 204 and font ROM 205.

Examples of the present invention will be described below assuming that the correspondence relationship as described above exists.

In FIG. 2, the character display device includes a display controller 201 that generates display addresses, a read/write memory (attribute VRAM) 203 that stores attribute data, and a character display that stores character codes. VRA
M204, a read-only memory (font ROM) 205 that stores character fonts, and an attribute system that processes character fonts based on attribute data? A JH unit 206, an access switching circuit 207 that outputs a CPU access signal based on an access request from a central processing unit (CPU), and a CP (J access ft) that selects either the display address or the CPU address based on the access request. Attribute VRAM203, character VI'
? Address switching circuit 202 that supplies AM204 and C
PU and Attribute 1-V RAM203. Character VR
A data buffer 208 that mediates data exchange with the AM 204, and a latch 2 that temporarily holds attribute data read from the attribute VRAM 203.
21, and input terminals A and B based on the CPU access signal.
a selector 22 for selecting one of the data input to the
2, and a character display section 209 that performs display.

The input terminal A of the selector 222 has an attribute VR.
Attribute data from the AM 203 is input, and the output of the latch 221 is input to the input terminal B.

The display address output from the display controller 201 is manually input to the address switching circuit 202 and the attribute control section 206, and corresponds to the display position of the character display section 209.

The CPU access signal output by the access switching circuit 207 is the address switching circuit 202 (attribute).
VRAM203. Character VRAM 204, selector 222
．． It is manually controlled by the attribute control unit 206.

Data buffer 20th is attribute VRAM20
3 and latch 221. It is connected to each of the data line A that connects the selector 222 and the data line B that connects the character VRAM 204 and the phono FROM 205.

Furthermore, the timing (basic cycle) at which the display address is output synchronizes the operations of exchanging data between the various parts.

FIG. 3 is a timing diagram illustrating the operation of the character display attribute control device according to the embodiment shown in FIG. 2.

Hereinafter, with reference to FIGS. 2 and 3, the operation of the embodiment will be explained separately into the operation in the display cycle and the operation in the CPU cycle.

The display controller 201 operating in the i-cycle generates display addresses corresponding to the display positions one after another as the display positions are scanned in the character display section 209 and inputs them to the address switching circuit 202 (see FIG. 3 (I)). )reference).

An address switching circuit 202 selects a display address and selects an attribute VRAM 203 and a character VRAM 204.
These memories are accessed based on the display address.

For example, the attribute VRAM203. When the character VRAM 204 is accessed, attribute data (see FIG. 3 (c)) and character code (see FIG. 3 (b)) are output to data lines A and B, respectively.

Attribute data (2) read out from the attribute VRAM 203 in this manner is input to the latch 221 and the input terminal A of the selector 222 in the next display cycle. The latch 221 outputs data corresponding to the display address one character before the display address ■, and holds the attribute data ■ instead.

The selector 222 selects the input terminal A in the display cycle.
Since the data inputted in is selected, the attribute data ■ is inputted to the attribute control section 206 (see FIG. 3(E)).

On the other hand, the character Vr? The character coat ■ retrieved from AM204 is font F? in the next display cycle. 0M2
Search for character font ■ from 05 (see Figure 3 (d)).

The character font ■ is passed to the attribute control unit 206 in the next cycle. The attribute control unit 206
Based on the character font■ and attribute data■,
For example, it is output as display data (see FIG. 3) for every 4 bits.

In this way, characters with attributes such as reverse display are displayed by the character display section 209, for example.

CPU in 1icPU cycle attributes VRAM203 and character VR
When accessing AM204, first
P[J is the CPU access request signal (see Figure 3 (H))
Output.

When the CPU access request signal is output at the falling edge of the basic cycle (see FIG. 3 (G)), the access switching circuit 207 regards this cycle as the CPU cycle and switches the CPU access signal (the first CPU access signal) synchronized with the basic cycle. (See Figure 3 (S)).

When the CPU access signal is input to the address switching circuit 202, the attribute VRAM 203
As the address specified in 204, the address specified by the CPU is valid. Therefore, the display address ■ output from the display controller 201 (Fig. 3 (
b)), the attribute VRAM203.
Attribute data and character codes are not read from the character VRAM 204.

The CPU has the attribute VRAM203 and the character V
Specify the address of RAM204 and connect data lines A and B.
Data is exchanged via the data buffer 208 and the data buffer 208. Therefore, in the next cycle of the CPU cycle, 5. The data on data lines A and B becomes CPU data as shown in FIGS. It is input to input terminal A of selector 222 and font ROM 205.

On the other hand, the latch 221 outputs attribute data ■ corresponding to the previous display address ■, and the selector 22
Input to input terminal B of No.2.

The selector 222 selects the CPU based on the CPU access signal.
It is determined whether or not U cycle data is input to input terminal A, and data input to input terminal B is selected.

As a result, the attribute data selected by the selector 222 does not change, so the attribute data ■ is output as the attribute data corresponding to the display address ■.

On the other hand, the character font ■ is read out from the font ROM 205 by the CPU data, but this character font is not regular data.

Therefore, in the attribute control unit 206, the CP
Based on the U access signal, it is determined whether the input character font has been read out by CPU data, and if the character font is not regular data, it is ignored and treated as blank.

In this way, for example, if the basic cycle corresponding to the display address ■ becomes a CPU cycle, the character display section 209 will display the display position corresponding to the display address ■.
Displays a blank space with a display attribute request using the attribute data ■ corresponding to the display address ■.

Jy-JJi ~ Down 9Jtsu [As described above, the selector 222 sets the C
In the PU cycle, the attribute data in the previous display cycle is used. Also,
Character fonts read from the font ROM 205 by CPU data are ignored, and displayed characters are treated as blanks.

Here, it is considered that the attribute data of a certain character is likely to be the same as the attribute data of the previous character.

Therefore, even if the character is displayed with the correct attribute data the next time the screen is scanned, there is a high possibility that the attribute will not change.
It is possible to reduce disturbances on the display screen of No.9.

Further, when the character display section 209 is a liquid crystal display (LCD), it is particularly effective because the response speed of the liquid crystal is slow, so changes in display are smoothed and disturbances are less noticeable.

1V, - Hatsuho Mu Huang J! LqJ1 In addition, in "■. Correspondence between Examples and Figure 1",
Although the correspondence between the present invention and the embodiments has been explained, those skilled in the art will readily understand that the present invention is not limited to this and that there are various modifications. Dew.

〔Effect of the invention〕

As described above, according to the present invention, when there is an access by the central processing unit, by selecting the display attribute data held in the holding means and displaying it with iff L, the disturbance on the display screen becomes less noticeable. , which is extremely useful in practice.

[Brief explanation of the drawing]

FIG. 1 is a principle block diagram of a character display attribute control device 21 of the present invention, FIG. 2 is a block diagram of the configuration of a character display device using a character display attribute control device according to an embodiment of the present invention, and FIG. 2
FIG. 4 is a timing diagram illustrating the operation of the character display attribute control device according to the embodiment shown in the figure, and FIG. 4 is an explanatory diagram of a conventional character display device. In the figure, toi is a control means, 102 is a display attribute storage means, 103 is a holding means, 104 is a selection means, i05 is a display means, 106 is a display character storage means, 107 is a central processing unit, 1 and 401 are display controllers, 2, 402 is an address switching circuit, 3, 403 is an attribute V R A ), 4, 4,
404 is a character VRAM. 5, 405 is a font ROM. (i,, 406 is the attribute control section, 7, 407 is the access switching circuit, 8, 408 is the data buffer, 9, /109 is the character display section, 1 is the latch, 2 is the selector, 0 is the central processing unit (CPU) It is. CPIJ"+I"27n+ The timing γ° to say that the 71st movement is 71
B-port Figure 3

Claims (1)

[Claims] (1) In a character display device in which characters are displayed by a display means (105) based on a character pattern retrieved from a display character storage means (106) and display attribute data retrieved from a display attribute storage means (102), Holding means (103) for temporarily holding the display attribute data read from the display attribute storage means (102); and Display attribute data read from the display attribute storage means (102) and the holding means (103). selection means (104) for selecting one of the data held in the display character storage means (106) and the display attribute storage means (102) based on whether or not the central processing unit (107) accesses the display character storage means (106) and the display attribute storage means (102). control means (101) for controlling the selection operation of the selection means (104); A character display attribute characterized in that, upon access, display is performed based on a character pattern retrieved from the character storage means (106) and display attribute data held in the storage means (103). Control device.