JPS61282894A - Display controller - 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 (Technical Field of the Invention) The present invention relates to a display control device, and particularly to a display control device whose display screen is configured to display information in a dot matrix format.

(Technical background of the invention and its problems) For example, an information processing device such as a personal computer or a handheld computer is equipped with a graphic display section for displaying input/output information, control commands, etc. . Therefore, the character data to be displayed is given from a character generator provided inside the device in accordance with a bit configuration defined for each character. Depending on the state of these configuration bits, characters are displayed using, for example, a dot matrix display format display device.

Incidentally, the number of dots constituting one character in the horizontal direction is different from the number of display unit bits (for example, byte unit) in the screen memory corresponding to display. Therefore, one character display may span two display units. In such a case, all bits (for example, 2 bytes) corresponding to two display units of one character are read out and stored again. As a result, it inevitably takes time to perform control operations for unnecessary bits.

(Object of the Invention) An object of the present invention is to provide a display control device that performs display control at high speed.

(Summary of the Invention) The present invention detects the part of the character that falls outside of a predetermined width area at the position where the character should be displayed, writes it into the memory, and prevents rewriting of bits other than the part that falls outside the specified width area. It is characterized by what it did.

(Embodiments of the Invention) Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows an embodiment of the present invention, in which a central processing unit (CPU) 110 performs control operations for the entire display device.

The character generator 120 is, for example, a read-only memory (ROM) that stores character data burned in each defined bit combination.
It is formed of. This character generator 120
generates a character signal 121 representing alphanumeric character data (for example, ASCII code) according to the character selection signal 111 from CPUll0, and outputs it to CPUIIG.

The screen memory 130 is formed of, for example, a random access memory (RAM). A memory control signal 113 supplied from the CPU 110 is used to issue instructions for writing to or reading from the memory and a memory address instruction.
Character data generated from the character generator 120 is sent to the screen memory 130 as a write data signal 115.
Character data written to or stored in the screen memory 130 is read out as a read data signal 117.

The display unit 140 has a dot matrix display format composed of LED elements, LCD elements, etc., and displays in response to a character display signal 131 based on character data stored in the screen memory 130.

FIG. 2(A) shows the display screen configuration of the display screen of the display unit 140 shown in FIG. 1 viewed from the display surface side. ing.

Also, as shown in Figure 2 (CB), one character is displayed in a dot matrix format of 6 dots horizontally x 8 dots vertically.

By the way, in the dot configuration described above, one character formed by the matrix is 6 x 8 dots, so if you look at one display character, it is 80 horizontally (=480 ÷ 6) x 8 vertically (= 64 ÷ 8).
) It is possible to display character characteristics.

On the display screen, the upper left character area (6 x 8 dots))
One screen is formed by a diagonal line between DARL and the lower right character area DA Rza. On such a screen, one character, for example, a character (“H”) shown roughly in the middle, can be moved upwards (↑), downwards (number), and leftward (
←), right direction (-), diagonally upward left direction (~), diagonally downward left direction (1), diagonally upward right direction (2), and diagonally downward right direction (-
) can be transferred arbitrarily.

The display unit 140 has such a screen configuration and operation.
Let's look at the correspondence between the screen memory 130 and the screen memory 130.

The storage capacity of the screen memory 130 must be at least large enough to collectively store character data for 80×8 characters displayed on one screen of one display unit 140. 1
Characters (6 x 8 dots)! Regarding lines, the horizontal display is 480 dots, and the screen memory 130 stores bit information equivalent to these 480 dots in byte format (8-bit units).

Therefore, as shown in Figure 2 (B), the correspondence between 0 character boundaries and byte boundaries, where the number of bits differs between character boundaries (6 bits) and byte boundaries (8 bits) forming one character. Since characters are displayed without taking
In some cases, it can be done with a part-time job (CHAI, CHA4), but
One character may span two bytes (CHA2, C
HA3).

Now, let us consider a case where the display unit 140 displays the characters CHA2 shown in FIG. 2(B) in a specific display area. As is clear from Figure 1, with this ζ, CHA
2 is off the byte boundary B8, and each spans two bytes. In this way, CHAI and CHA
The display of a character different from a character that falls within the byte boundary BII, such as 4, will be explained.

3rd rI! I shows the operation of the M control of the embodiment of the present invention shown in FIG. 1. Hereinafter, FIGS. 1 to 3 will be referred to.

First, one character selection signal 111 is activated under the control of CPUll0.
The character generator 120 is instructed to generate the alphabet "H", and the character "H'" is generated.
A character signal 121 of character data representing . As a result, the character pattern 'H' is taken into CPUll0 (step 311).

The position to be displayed on the screen is now shifted to the left by a portion Ap corresponding to two dot rows from the byte boundary, as indicated by CHA2 in FIG. 2(B). Therefore, the one character pattern is shifted to the left by two dot rows (shift amount) corresponding to the position to be displayed (step 312).

In parallel with executing both steps 311 and 312 above, CPUll0 generates a mask pattern corresponding to the display position (step 321).

Next, the data stored in the screen memory 130 corresponding to the position to be displayed on the screen of the display unit 140 is read out (step 322). In this case, the screen memory 1
Address designation of the storage area 30 is performed by a memory control signal 113 from the CPU 110. This signal 113 also commands the "read" mode.

Next, the display portion is masked in accordance with the mask pattern generated as described above in step 321 (step 323). By this masking, desired data can be written.

As described above, after steps 3i1 to 312 and steps 321 to 323 of both systems are executed in parallel, the process moves to the first step 331. However, after parallel execution,
It is necessary to execute step 331 synchronously. Kire actually requires a step to give one of the systems a temporal pause function.

In step 331, the "image from which the display portion has been removed" is obtained as a result of the masking in step 323.
The data and the "display pattern" data obtained as a result of steps up to step 312 are superimposed. To do this, we need to logically OR both data, which gives us
Character pattern data is obtained at the positions of characters CHA2 and CHA3 beyond the byte boundary, as shown in FIG. 2(B). This data is re-stored in the screen memory 130 from cptriio as a write data signal 115 according to the address specification of the memory control signal 113. still,
The designated address in this case is the address of the screen memory 130 read out in step 322.

By supplying the data stored in the screen memory 13G to the display section 140 as the character display signal 131,
The character CHA2 is displayed in a dot matrix as shown in FIG. 2 CB). In other words, when displaying a character that spans a 2-byte area, data is not fetched and re-stored for all 2 bytes, but the part that deviates from the byte boundary is retrieved and rewritten, resulting in faster 1-display control operations. be done.

In the above-described embodiment, dots are displayed separated by bytes, but the present invention is not limited to bytes, and the present invention is also applicable to other display configurations separated by a predetermined number of bits. It is.

(Effects of the Invention) According to the present invention, a display control device achieves faster control operations by detecting a portion that deviates from a display area of a predetermined width and rewriting it into the screen memory at the position to be displayed. can be realized.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of a display control device according to an embodiment of the present invention, and FIGS. 2 (A) and (B) are a single screen configuration and a dot matrix on the display section of the device according to the embodiment of the present invention. A configuration diagram for explaining the display format, and FIG. 3 is a flowchart showing the order of control operations in the apparatus according to the embodiment of the present invention. 110-----Central processing unit (CPtl), 12
0---Character generator, 130--
-----One screen memory, 140---One display section,' 111---Character selection signal. 113--11--Memory control signal, 115--
1--Write data signal, 117--Read data signal, 121--One character signal, 131--One character display signal. Figure 1 Figure 2 (A)

Claims (1)

[Scope of Claims] 1. A matrix display format is adopted in which one character is displayed in m width x n dots length, and the desired character is displayed on the display section having a predetermined width area separated by γ dots in the horizontal display direction. When displaying at a certain position, only the part that is outside the predetermined area and the part that falls within the predetermined area are learned and combined,
A display control device characterized in that the character data resulting from the combination is stored again in a memory area corresponding to the desired position, and the memory area is displayed. 2. The display control device according to claim 1, wherein the γ dots correspond to byte units.