JPS63271288A - Window display device - 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 [Field of Industrial Application] The present invention relates to a window display device, and is applicable to, for example, personal computers and word processors.

[Prior Art] Conventionally, graphic display devices in personal computers, word processors, etc. have a RAM (random a) corresponding to the display screen, as shown in FIG.
The image data is stored in the graphic memory 1, and the image data is sequentially outputted from the memory 1 according to an address synchronized with a scanning line given from a display address generation circuit 2. This image data was converted into serial data in a parallel/serial conversion circuit 3, and then presented to a cathode ray tube display device for display.

Depending on the user's usage, it may be necessary to display multiple double-sided images at the same time, and it may be necessary to control the storage of image data in the graphic memory, or to allocate a part of the main image by controlling the read address from the graphic memory. Many things are being done to display other images (windows) at the same time. Conventionally, such window display methods include a software method and a hardware method.

Among these methods, the software method overwrites the bit image data that should be displayed within the window in the memory area corresponding to the display image in the reverse order of the window priority while performing area identification processing (clipping processing). However, this method is performed by sequentially changing the read address in accordance with the scanning line.

As shown in FIG. 5, the hardware method stores the main image MM and window images WMI to WM3 in different memory areas RMM and Wl to W3, and outputs them from the display address generation circuit 2 (FIG. 6). Each window discrimination circuit 4-6 determines whether the address corresponding to the scan line indicates the area RWI-RW3 designated as the area for displaying the window image, and selects the window area RWI-RW3.
At this time, the corrected address (for example, PI-PO) is output from the register circuit 7, and the address is converted by the adder 8 to specify the memory area Wl-W3 storing the window images WMI-WM3. This is the method to do it.

[Problems to be Solved by the Invention] However, with the above-mentioned software method, when there are many windows to display, overwriting is repeated, so the clipping process takes a lot of time and the response speed decreases significantly. There's a problem.

In addition, the above-mentioned hardware method has a faster response speed because there is no clipping process, but it requires the same number of window discrimination circuits as the number of windows, making the configuration complicated and large. Ta.

The present invention has been made in consideration of the above points, and it is an object of the present invention to provide a window display device that can display a plurality of window images at high speed and with a simple configuration.

[Means for solving the problem] In order to solve the problem, the present invention provides a graphic memory that stores image data of a main image and at least one window image in different areas, and a graphic memory that stores image data of a main image and at least one window image, and a first address generating means that generates a reference read address for the graphic memory that changes sequentially in accordance with the image data; and an identification number memory that stores identification numbers of the main image and each window image for each unit area of the display screen. , an identification number/difference data conversion means that receives the identification number and outputs difference data between the address of the area storing the image data of the window image or main image indicated by the identification number and the reference read address; A second address generation means generates a read address for the identification number memory according to the position of the scanning line, and a second address generation means generates a read address for the identification number memory according to the position of the scanning line, and a second and an addition means for adding the reference read address outputted from the first address generating means to obtain a read address for the graphic memory.

[Operation] In response to the read address output from the second address generation circuit, the identification number memory outputs the identification number stored at that address, and thereby the identification number/difference data conversion means outputs the difference data. do. This difference data is added to the reference read address in the adding means, and when the scanning position is within the main image area, the data is read from the area of the graphic memory that stores the image data of the main image, and when the scanning position is within the window image area. When the image data of the window image is stored, data is read from the area of the graphic memory that stores the image data of the window image, and the image data of the main image and the window image are output.

As a result, when the reference read address is generated on the rask scan, differential data that changes the address according to the window display can be generated using the identification number memory and conversion means, and clipping This eliminates the need for processing, which enables high-speed display, and also simplifies the overall configuration by eliminating the need for a component that determines whether the scanning position is within the area for each window.

[Embodiment] First, the principle configuration of the present invention will be explained based on FIG. 1, in which the number of window screens is two, and corresponding parts to those in FIG. 4 are denoted by the same reference numerals.

In FIG. 1, an identification number memory 10 having a RAM configuration is
It has a memory space corresponding to the screen, and has a memory space corresponding to the main screen (for example, 4 pixels in the horizontal direction,
An identification number (hereinafter referred to as a window number) "0" is stored in each memory area corresponding to the window image (consisting of one line in the vertical direction), and the window images with lower priority are stored in the memory area corresponding to the unit area of the window image. The window numbers "1" and "2" with the lowest values are stored in order.

The identification number memory 10 outputs window numbers sequentially stored in a raster scan pattern in accordance with read addresses given from the address generation circuit 11 in synchronization with the scanning lines. This window number is given to the window number/address difference data conversion table 12.

In the present invention, as shown in FIG. 2(D), image data MM of the main screen is stored in the display area RMM in the graphic memory 1, and image data of each window image is stored in the display area RMM. The data is stored in memory areas Wl and W2 that do not conflict with the area of the window image.

Therefore, the read address for the display area RMM changes, and for example, when specifying the starting point AO of the display area RWI of the window image WMI as shown in FIG. 2(D), the starting point of the storage area W1 of the window image WM1 is It must be changed to A1. Similarly, the addresses of other points in the window picture @WM1 must be changed in the same way. This amount of change ΔA can be expressed as the difference between addresses as follows: ΔA=A1-AO (1).

The window number/address difference data conversion table 12 described above receives the window number "1" as an address and outputs this address difference data ΔA. Similarly,
When the window number is "0", the main image MM is specified, so address difference data whose content is "0" is output, and when the window number is "2", the second window image WM2 is output. Difference data ΔB (=81
-BO) is output.

The difference data thus output is added to the reference read address output from the display address generation circuit 2 in an adder 8 to form a final read address, which is then applied to the graphic memory 1.

In the above configuration, the identification number memory 1
As the address relative to 0 changes, the window number of the area corresponding to the address is output, and the conversion table 12 outputs differential data according to the window number, which is input to the adder 8 from the display address generation circuit 2. It is added to the address to designate the memory area of the graphic memory 1. According to this address, when the position of the scanning line reaches the window area RWI, RW2, the address is synchronously offset by the difference data, and the memory area W1, which stores the window image data,
Image data is read from W2. In this way, image data for realizing window display is sequentially applied to the cathode ray tube display device.

Note that FIG. 2(C) is a two-dimensional representation of the output data from the conversion table 12.

FIG. 3 shows an embodiment embodying this principle configuration. In FIG. 3, in which parts corresponding to those in FIG. 1 are given the same reference numerals, a central processing unit (CPU) 15 has a
According to the program stored in OM (read only memory) 16, the working RAM 1
7 is used to control the window display operation.

For example, it controls the storage of image data in the graphic memory 1, the storage of window numbers in the identification number memory 10, the storage of difference data in the window number/address difference conversion table 12, and the like.

That is, the CPU 15 sends image data to the data bus 18, opens the bus switch circuit 19, closes the bus switch circuits 20 and 21, provides the image data to the graphic memory 1, and sends an address to the address bus 22. It is sent out and given as a write address to the graphic memory 1 via the multiplexer 23 to store the image data of the main screen and window screen.

Further, the CPU 15 sends the window number to the data bus 18, opens the bus switch circuit 20, closes the bus switch circuits 19 and 21, gives the window number to the identification number memory 10, and sends the window number to the address bus 2.
2, the address is sent to the identification number memory 10 via the multiplexer 24 as a write address, and the window number is stored therein.

Further, the CPU 15 sends the address difference data to the data bus 18, opens the bus switch circuit 21, closes the bus switch circuits 19 and 20, provides the address difference data to the conversion table 12, and sends the address difference data to the address bus 22. The address (window number) is sent out and given as a write address to the conversion table 12 via the multiplexer 25 to store the address difference data of the window screen.

In this embodiment, one address generation circuit 30 performs the functions of the display address generation circuit 2 and the address generation circuit 11 for the identification number memory 10 in FIG.

In the above configuration, the CPU 15 stores data in each of the memories 1, 10, and 12 as shown in FIG. 2 (A>, (B), and (D>) using the idle time of the read operation.

In this state, when the address generation circuit 30 outputs a read address corresponding to the position of the scanning line, the window number of the window corresponding to the scanning position is output from the identification number memory 10, and the difference data is output from the conversion table 12. Output. This difference data is added to the address from the address generation circuit 30 in the adder 8 to form an address for the graphic memory 1, and outputs image data from the graphic memory. This image data is converted into serial data in the parallel/serial conversion circuit 3 and applied to the cathode ray tube display device to perform window display.

Therefore, according to the above embodiment, there is no need for a circuit for each window to determine whether the scanning position is in the area of the window concerned, and the configuration can be made simple and compact. In addition, there is no need to overwrite the graphics memory while taking the area into consideration, allowing high-speed operation and high-speed display.

Incidentally, in order to obtain address difference data for each window without using a discrimination circuit, an identification number memory,
This can be done by using one memory (the stored contents are as shown in Figure 2 (C)) that stores the address difference data for each unit area, without dividing the conversion table into two parts. However, in this case, it is inferior to the case according to the present invention using an identification number memory and a conversion table in the following points.

First, when scrolling the window area, if you use a conversion table, you can easily do this by changing only the difference data stored in the conversion table, but with a method that does not use a conversion table, All differential data within the window area must be converted, which cannot be executed quickly. Second, when 16 windows can be displayed, the window number is, for example, about 4 bits of data, but the differential data is determined by how the unit area is determined, and is, for example, about 16 bits of data. The method of storing the window number and the difference data can make the memory capacity much smaller than the method of storing the difference data for each unit area.

In the above description, the size of the unit area for storing the window number is 4 pixels x 1 line, but the present invention is not limited to this, and the size can be determined as needed. good.

In addition, although the above example shows a case with one identification number memory, in order to prevent flickering on the screen when switching the priority order of windows, this memory is divided into two.
Alternatively, a window number variable operation may be performed in one memory in accordance with priority switching, and when the operation is completed, data may be instantaneously transferred to the other memory where a read operation is performed.

Furthermore, in the above description, the value of the difference data with respect to the main screen is "0", but by making the display area in the graphic memory and the storage area of the main screen image data different, the value of the difference data can be changed to "0". It may be set to a value other than 0.

[Effects of the Invention] As described above, according to the present invention, a window number is stored for each unit area, and read address difference data is obtained based on the read window number to determine the reference read address of the graphic memory. Since the graphic memory is accessed by changing the , it is possible to obtain a window display device that can perform a window display operation at high speed with a simple configuration.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the principle configuration of the present invention, FIG. 2 is a route map showing data stored in each memory, FIG. 3 is a block diagram showing an embodiment of the window display device according to the present invention, and FIG. The figure is a block diagram showing a conventional display device that does not have a window display function.
The figure is a block diagram showing a conventional device having a window display function. DESCRIPTION OF SYMBOLS 1... Graphic memory, 2... Display address generation circuit, 8... Adder, 10... Identification number memory,
11... Address generation circuit, 12... Window number/address difference data conversion table.

Claims (1)

[Scope of Claims] A graphic memory that stores image data of a main image and at least one window image in different areas, and a reference read address for the graphic memory that sequentially changes according to the position of a scanning line. The first to generate
an identification number memory for storing the identification numbers of the main image and each window image for each unit area of the display screen; identification number/difference data converting means for outputting difference data between the address of the area storing the image data of the image and the above-mentioned reference read address; and generating a read address for the above-mentioned identification number memory according to the position of the scanning line. and a second address generation means that converts the difference data outputted from the identification number/difference data conversion means based on the identification number from the identification number memory into the reference outputted from the first address generation means. A window display device comprising: adding means for obtaining a read address for the graphic memory by adding the read address to the read address for the graphic memory.