JPS6234191A - 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 The present invention relates to a display control device in which a display area of a display device can be arbitrarily set.

<Prior Art> Generally, in a personal computer 3, a method is desired in which data is displayed only on a specific part of the display screen to draw the operator's attention when displaying a game function or guidance.

Conventionally, for this purpose, display data such as "all zeros" was created and displayed in the display area other than the specific portion.

Therefore, the conventional method had problems such as an increased burden on the software.

<Object of the Invention> In view of the above circumstances, the present invention provides display control in which target display data is stored in a specific part of a display memory, and a display area can be arbitrarily set regardless of data in other parts. The purpose is to provide equipment.

<Example> Hereinafter, the present invention will be described in detail based on Examples.

FIG. 1 shows a block configuration of a display control device according to an embodiment of the present invention, and in the figure, l represents a central processing unit CPU'i that performs various processes.

Further, 2 is a main memory in which programs and data processed by the CPUI are stored.

The CPU I is connected to the main memory 2, an input/output device 3, and a display memory 4 via a pass line B.

The display data written into the display memory 4 by the CPU I is sequentially read out by the display control unit 5,
The read display data is sent to the display device 6.

The input/output device 3 executes input/output other than the display device 6, and includes a keyboard, a printer, a disk device, and the like.

Next, the specific structure will be explained using FIG. 2.

In the figure, 7 is a display memory for storing character data, and if the memory is for storing character codes, it has a well-known character pattern generator at the rear stage. In this embodiment, it is assumed that character data expanded into dots is stored.

8 is a memory for storing graphic data.

The image display memory 7.8 has a capacity equal to or greater than the maximum display capacity of the display screen, and stores input data or display data generated from software under the control of the CPU.

Also, 9. IO is a display control circuit, and a predetermined C
Data read from the display memories 1 and 2 is supplied to the display device 6 in accordance with a timing signal from a timing generation circuit 11 that is synchronized with raster scanning of the RT display device.

This display control is a well-known matter in CRT display technology, and brightness information is output according to each raster.

The timing generation circuit 11 sends out a timing signal t1 for each horizontal scanning position (each dot position or predetermined character position), and also outputs a timing signal t1 for each horizontal scanning line (or character line unit). A signal t2 is output.

I2 is the timing signal 1. This is a horizontal display position counter that counts the current display position in the horizontal direction.

13 is a vertical display position counter that counts the timing signal t2, and indicates the current display position in the vertical direction.

Reference numeral 16 denotes a register for storing the horizontal display start position and display end position, respectively, according to software commands.

Reference numeral 17 is a register for storing the vertical display start position and display end position, respectively, according to software commands.

14 is a comparison circuit which connects the counter 12 and the register 1.
6, it is determined whether the current display position is within the horizontal display start position and the horizontal display end position, and a comparison signal thereof is output.

15 is a comparison circuit that connects the counter 13 and the register 1;
7, it is determined whether the current display position is within the vertical display start position and the vertical display end position, and a comparison signal thereof is output.

Both of these comparison signals are outputted as a blanking signal by a mixing circuit consisting of, for example, an AND gate, mixed with display data from the character display control circuit 9, and supplied as a luminance signal to the display device via the mixing circuit 21.

Therefore, only when the current display position is within the range specified by registers 9 and 10, the output from display control circuit 9 is supplied to the CRT display device for display.

20 is the above counter 12.13, comparison circuit +4°15,
Display control similar to that described above is performed also in the graphic display, which does not have the same configuration as the registers 16 and 17.

Therefore, when the CPU specifies character display by software, the character display control circuit 9 is driven, reads out the display data from the character display memory 7,
On the other hand, if the CPU specifies graphic ink display using software, the graphic display control circuit 10 is driven and the display is performed based on the circuit 20.

Further, when it is specified that the image display is to be displayed in a composite manner, both circuits are driven, and each display range is individually specified and displayed.

The actual display control described above will be explained using FIG. 3, FIG. 4, and FIG. 5.

As shown in Figure 3, from the display screen piece to the right, from top to bottom,
Scanning for sequentially reading out the contents of the display memory 4 and sending them to the screen is performed about VC60 times per second.

The display position counters 12 and 13 indicate whether the scanning is at the current position. Regarding the horizontal direction, as shown in FIG. 4, the horizontal display start position 2. and the horizontal display end position Z2 are stored in the register 16 by the CPU 1.
The above-mentioned comparison circuit 14 compares the current scanning position, the display start position Z1, and the display end position Z2.
A blank signal is generated to erase the display before the display start position Z1 and after the display end position Z2.

When similar processing is performed in the vertical direction, the comparison circuit 15 compares the current scanning position stored in the display position counter 13 with the display start and end positions stored in the register 17.
A predetermined blank signal is generated in response to the comparison result.

By combining the two blank signals in the total mixing circuit 18 and combining them with the character display data in the mixing circuit 19, it becomes possible to display a rectangular portion of any size as shown in FIG. In addition, xl in FIG.

X2+ Y I+ Y2 defines the display position,
The details are as shown in the table below.

By combining the character data and the bright data in the mixing circuit 21 and sending it to the display device, it becomes possible to partially erase only the characters.

Effects> As described above, according to the present invention, in a display device that has a display memory that is equal to or larger than the maximum display capacity of a display screen and that reads out the display memory in synchronization with the display cycle, storage means for storing the set horizontal and vertical display areas of the display screen; comparison means for comparing the display area stored in the storage means with the current display position of the display device; and an output of the comparison means. and an output means for outputting the read display data of the display memory in response to the display data, and the display device displays a predetermined display area. It becomes possible to display only an arbitrary part on the display screen without rewriting data, and the burden on software processing can be reduced.

[Brief explanation of the drawing]

1 and 2 are block diagrams of a display control device of the present invention, and FIGS. 3 to 5 are diagrams for explaining display control of the device. 7... Character display memory, 8... Graphic display memory, 9... Character display control circuit, 10. Graphic display control circuit, 11... Timing generation circuit, 12. Horizontal (horizontal) direction display position counter, 13...Vertical (vertical)
Direction display position counter, 14.15... Comparison circuit, 16
...Horizontal (horizontal) direction display start and end position register, 1
7... Vertical (vertical) direction display start and end position registers,
+8.19.2)...Mixing circuit, Xl...Horizontal (horizontal) display start position, X2...Horizontal (horizontal) display end position,
Y,... Vertical (vertical) display start position, Y2... Vertical (
Vertical) display end position.

Claims (1)

[Claims] 1. In a display device that has a display memory that is equal to or larger than the maximum display capacity of the display screen and that reads out the display memory in synchronization with the display cycle, storage means for storing horizontal and vertical display areas; comparison means for comparing the display area stored in the storage means with the current display position of the display device; However, a display control device comprising an output means for outputting the display data of the display memory, so that a predetermined display area is displayed on the display device.