JPH02220184A - Graphic display device - Google Patents

Abstract

PURPOSE:To display a picture by means of a buffer memory having small window display in a double buffer system by utilizing the display area of a frame buffer memory and the excessive part of the frame buffer memory. CONSTITUTION:For the window displayed by the double buffer, a window display processor 10 designates a window A on a display area 3A of a frame buffer memory 3 and a window B on an area 3B other than the display area 3A. When a display processor 5 makes the window in a certain limited range into a buffer object, the processor 5 writes the graphic on the areas 3A and 3B of the frame buffer memory 3 according to the window display table 10. A display control circuit 11 reads and displays one of the area 3A or 3B of the window in which the frame number memory 3 is double-buffered. Thus even when two sets of the frame buffer memories are not possessed, the double- buffered display is attained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a graphic display device, and particularly to a graphic display device using a double buffer method when displaying a window.

The conventional double-buffer type graphic display device
As shown in the figure, cptrt, a main memory 2, two frame buffer memories 3 and 4, a display processor 5 that controls writing of graphics to the frame buffer memories 3 and 4, and a frame buffer memory 3.
and 4, a D/A converter 7 that converts the digital signal from the selector 6 into an analog signal, and a display means 8 such as a CRT.

In this graphic display device, while one frame buffer memory (e.g. 3) is being displayed on the display screen, the display processor 5 newly draws data in the other 7 frame buffer memory (e.g. 4). Ru. That is, while one frame buffer memory is being displayed, drawing is performed in the other 7-frame buffer memory, and the two sets of frame buffer memories are switched by the selector 6 as necessary to be displayed on the display means 8.

Thus, in the conventional graphic display device, it is necessary to have two sets of frame buffer memories. When displaying with 256 display colors using the double buffer method, two sets of 8-plane frame buffer memories (3
and 4) must have.

Furthermore, as shown in FIG. 5, if you try to display using the double buffer method with a limited number of planes, for example, if you have only one set of frame buffer memory for 8 planes,
While the number of colors that can be displayed simultaneously in a normal single buffer is 256, in the case of a double buffer, the number of colors that can be displayed simultaneously is drastically reduced to 16.

When displaying in the window display mode, when displaying only a certain part of the window in the double buffer mode (
For example, in FIG. 4, for window A on frame buffer memory 3 and window B on frame buffer memory 4, drawing data other than the window to be double buffered is also drawn in the other frame buffer memory. must be kept, i.e.,
Around the window targeted for double buffering,
Exactly the same data is written to the two sets of buffer memories.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a graphic display device that can perform window display using a double buffer method using a small amount of buffer memory.

According to the present invention, a memory that stores a screen image to be displayed on a display screen, a display processor that draws a figure on the memory, and a display processor that draws a figure on the memory correspond to the display surface. A figure comprising a window display table that sets windows in a display area on the memory and an area other than the display area, and displays a figure on the display screen according to instructions from the table. A display device is obtained.

Week 11 Next, the present invention will be explained in more detail with reference to the drawings showing one embodiment of the present invention.

FIG. 1 is a block diagram of an embodiment of the present invention, and parts equivalent to those in FIG. 3 are designated by the same reference numerals.

One embodiment of the present invention includes a CPUI, a main memory 2,
A frame buffer memory 3 of 2048x 1024 bytes, a display processor 5 that controls writing of graphics to the frame buffer memory 3, a window display table 10, a display control circuit 11, a D/A converter 7, and a display means 8. It consists of

The window display processor 10 designates windows A on the display area 3A of the frame buffer memory 3 and window B on an area 3B other than the display area 3A as windows to be displayed by double buffering.

For example, as shown in Figure 2, when displaying on a CRT with a resolution of 1280 x 1024 bytes, 2 Mbytes (2048 x 1
024 bytes) of memory, 1280x 1G2
The 4-byte portion is the display area 3A, and the remaining portion 76
A memory area of 8x1024 bytes is designated as area 3B, and this area 3B is used to store one of the two windows to be double buffered.

When a certain limited range of windows is to be subjected to double buffering, the display processor 5 writes graphics in areas 3A and 3B of the frame buffer memory 3 according to the window display table 10.

The display control circuit 11 reads out one of the double buffered window areas 3A and 3B from the frame buffer memory 3 and displays it on the CRT according to the window display table 10.

As explained above, according to the present invention, by using the display area of the frame buffer memory and the surplus part of the frame buffer memory, it is not necessary to have two sets of frame buffer memories as in the conventional case. However, a limited range of windows can be displayed using double buffering. This reduces the memory required for double buffering, and also has the effect that drawing on the display screen can be done in an instant due to the effect of double buffering.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a graphic display device according to an embodiment of the present invention, FIG. 2 is a diagram showing the configuration of a frame buffer memory in this embodiment, and FIG. 3 is a block diagram of a conventional double-buffer type graphic display device. Figure 4 shows the frame buffer configuration for double buffering when displaying 256 colors simultaneously using the conventional method, and Figure 5 shows the frame buffer configuration for double buffering when displaying 256 colors simultaneously using the conventional method.
FIG. 4 is a configuration diagram of a frame buffer when a plane is divided into 4 planes×2. Explanation of symbols of main parts 3...Frame buffer memory 3A, 3B...
...Memory areas A, B...Window

Claims (1)

[Claims] (1) A memory that stores a screen image to be displayed on a display screen, a display processor that draws figures in the memory, and a window that stores a display area on the memory corresponding to the display screen and an area other than the display area. 1. A graphic display device comprising: a window display table for setting each window display table, and displays a graphic on the display surface according to instructions from the table.