JPS62276589A - Scrolling system for 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 3. Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a scrolling method for a display device, and particularly to a scrolling method for a display device in an information processing device such as a personal computer or a word processor.

[Conventional technology]

Conventionally, in the scrolling method of this type of display device, the CPU
scrolling was achieved by repeatedly reading out all the character shapes developed in the video memory line by line and writing them to the destination line, thereby moving the character shapes in the video memory.

[Problem that the invention seeks to solve]

In the scrolling method of the conventional display device described above, scrolling is achieved by moving all the character shapes line by line within the video memory, so there is a drawback that the display speed during scrolling is slow.

For example, a personal computer whose screen size is 80 columns x 25 lines and one character is expressed as 8 x 16 dots, or 16 bytes, requires a video memory of 32,000 bytes; If you scroll by moving all character shapes line by line across the entire range on the screen, it will require 80 x 24 x 16 = 30,720 bytes of memory transfer, which will slow down the scrolling display speed. ing.

There is no CPU dedicated to scrolling, but the same CPU
For information processing devices such as personal computers and word processors in which U must also perform other tasks, when the burden on the CPU due to memory transfer increases as described above, it not only slows down the display speed of scrolling but also affects the overall performance. It also has the disadvantage of having negative effects.

Particularly, when an application program that involves a lot of scrolling is executed, the performance deteriorates significantly.

In view of the above-mentioned points, an object of the present invention is to provide a scrolling method for a display device in which the display speed during scrolling is high and the load on the CPU during scrolling is reduced.

Means for Solving Problem c] The scrolling method of the display device of the present invention is a display device that reads character shapes from a character generator that stores character shapes, develops them in a video memory on a main memory, and displays characters. In the scrolling method, the screen display character code storage means stores the character code of the character displayed on the screen, and the screen display character code storage means stores the characters that need to be moved and the characters that are not needed to be moved in the video memory at the time of scrolling. a character code identifying means for identifying a character code based on a character code identifying means; a video memory updating means for updating a video memory at the time of scrolling based on a determination by the character code identifying means; and a character code of a new displayed character on a screen after scrolling. and screen display character code updating means for updating and registering the screen display character code in the screen display character code storage means.

[Effect]

In the scrolling method of the display device of the present invention, the screen display character code storage means stores the character codes of the characters displayed on the screen, and based on the memory, the character code identification means selects the characters in the video memory during scrolling. Characters that need to be moved and characters that are not needed are identified, and based on this determination, the video memory updating means updates the video memory and scrolls the screen of the display device. When the scrolling is completed, the screen display character code updating means updates the screen. The character code of the new displayed character above is updated and registered in the screen display character code storage means.

〔Example〕

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

FIG. 1 is a block diagram showing the configuration of an embodiment of a scrolling method of a display device according to the present invention. The scrolling method of the display device of this embodiment includes a CPU, a bus 2 for data transfer, a main memory 3, and a display control device 6 that reads information from a video memory 5 in the main memory 3 and converts it into a display signal. and,
It is composed of a display device 7 that displays a display signal from a display control device 6 on a screen, and a character generator 8 that stores character shapes.

The main memory 3 includes a screen display character code table 4 that stores character codes of characters being displayed on the screen, and a video memory 5 in which character shapes read out from the character generator 8 by the CPU 1 are developed.

Referring to FIG. 2, the process in the scrolling method of the display device of this embodiment includes scroll end determination step 11.
, a video memory update target detection step 12 , a video memory update step 13 , a target row update step 14 ,
This step consists of a screen display character code table update step 15.

Next, the operation of the scrolling method of the display device of this embodiment configured as described above will be explained.

When attempting to scroll, the CPU 1 searches the screen display character code table 4 in the main memory 3. This search is performed in units corresponding to one line of the screen display, and is sequentially performed for all lines in the scroll range excluding the bottom line in the case of scrolling up and the bottom line in the case of scrolling down.

In this search, first, in order to determine whether scrolling has ended, it is determined whether the line to be searched exceeds the scroll range (step 11).

Next, if it is determined in step 11 that the scroll range has not been exceeded, the character code of the target line (hereinafter referred to as the moving rod) where the target line will be moved by scrolling is determined according to the screen display character code table 4. The character codes of the target line are compared, and it is determined whether the character codes of the pioneer characters in these two lines are the same or not, and different digits are detected (step 12).

Based on this identification result, the CPUI updates the video memory 5. That is, only the portion of the target line in which the character shape of the character in the digit detected in step 12 is developed is moved to the position where the character shape of the character in the opening of the moving rod is developed. Furthermore, the video memory 5 updated in this way
The display control device 6 reads out the contents of the moving rods in the display via the bus 2, converts it into a display signal, and displays it on the display device 7 (step 13).

Next, the line to be searched on the screen display character code table 4 is updated to the next line (step 14), and the process returns to the determination in step 11.

In step 11, when it is determined that the scrolling has ended based on the determination that the search target line exceeds the scroll range, the screen display character code table 4 is updated to reflect the scrolling results (step 15). , the scrolling process of the display device of this embodiment is completed.

〔Effect of the invention〕

As explained above, the present invention searches a table that stores the character codes of characters displayed on the screen at the time when scrolling is attempted, row by row, and moves to the destination row by scrolling. By identifying characters that need to be moved and characters that do not need to be moved, and moving the corresponding part of the video memory only for the characters that need to be moved, the amount of video memory movement required during scrolling is reduced. This has the effect of increasing the display speed and reducing the burden on the CPU during scrolling.

In particular, since the transfer of blank characters, which are usually often displayed at the right end of the screen, during scrolling is suppressed, the above-mentioned effect becomes remarkable.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention, and FIG. 2 is a flowchart showing processing in the scrolling method of the display device shown in FIG. In the figure, 1...cpu. 2... Bus, 3... Main memory, 4... Screen display character code table, 5... Video memory, 6... Display control device, 7... Display device, 8... Character Generator, 12... Video memory update target detection step, 13... Video memory update step, 14... Target line update step, 15... Screen display character code table update step.

Claims (1)

[Claims] In a scrolling method of a display device that reads character shapes from a character generator that stores the character shapes and expands them into a video memory on the main memory to display the characters, a screen display character code storage means for storing a character code; a character code identification means for identifying characters that need to be moved in the video memory during scrolling and characters that are not necessary based on the screen display character code storage means; a video memory updating means for updating the video memory during scrolling based on the determination by the code identification means; and updating and registering the character code of a new displayed character on the screen after scrolling in the screen display character code storage means. A scrolling method for a display device, comprising: screen display character code updating means.