JPH02272623A - Display device - Google Patents

Abstract

PURPOSE:To instantaneously change a background color in accordance with operator's choice by synthesizing a required pattern generated in a background pattern generator storing plural background patterns with the output of a frame memory and generating a video signal. CONSTITUTION:Four kinds of background patterns P0 to P3 are stored in the background pattern generator 6 and one of the patterns P0 to P3 is selected by the combination of the outputs C0, C1 of a background pattern selecting register 5. When C0 = '1' and C1 = '1' are set up in the register 5 from a CPU 1, the pattern P3 is read out from the generator 6, the pattern P3 is synthesized with the plotted pattern of the frame memory 2 by an OR circuit 8 and the synthesized pattern is displayed on the screen of a CRT 4. Consequently, effects such as the instantaneous change of the background can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Scope of Industrial Application] The present invention relates to a display device that displays graphics and the like using a monochrome CRT.

[Conventional technology]

Normally, this type of display device has one plane of frame memory for storing one graphic pattern, and one dot of the graphic pattern displayed on the CR7 screen is stored in correspondence with one bit of the frame memory. , 1 bit "0" and "1" are displayed on the CRT as two gradations of light and dark.

FIG. 3 is a block diagram showing a conventional display device, in which (1) indicates a CPU that controls the device;
(2) stores one dot of the graphic pattern drawn by c p u (t) as one bit, and has a storage capacity equal to the resolution of the CRT screen.

Furthermore, a frame memory (3) that performs a read operation in synchronization with the display timing of the CRT converts the dot information read out from the 7 L/-memory (2) at a display timing (not shown) into a serial video signal. The parallel-to-serial conversion circuit (4) is a CRT.

In such a configuration, if it is desired to display the background in white on the CR7 screen, "I" is written in the entire storage area of the frame memory (2), and "0" is written in the bits corresponding to the dots of the two-figure pattern. As a result, a black graphic pattern on a white background can be displayed on the CRT screen. In addition, if it is desired to display the background in neutral gray, it is also possible to display the background in pseudo-gray on the CRT screen, for example, by writing "l" for each dot in the horizontal and vertical directions.

[Problem to be solved by the invention]

Conventional display devices are configured as described above, so in order to display the background, frame memory (2) is required.
It was necessary to rewrite the entire storage area of the background pattern with the background pattern, which required a lot of processing time, and it was therefore impossible to instantly change the background color according to the operator's preference.

This invention was made in order to solve the above-mentioned problems, and its purpose is to provide a display device that allows an operator to select any preset background color and instantly displays a display according to the operator's preference. do.

[Means for Solving the Problems] A display device according to the present invention uses a background pattern generator that stores a plurality of background patterns, synthesizes a desired pattern from the background pattern generator and the output of a frame memory, and generates a video signal. It is designed to generate.

[Effect]

The display device according to the present invention can display the background without rewriting the contents of the frame memory by selecting a desired pattern from the background pattern generator.

[Embodiments of the invention]

Hereinafter, in FIG. 1, which explains one embodiment of the present invention using figures, (I) is a CPU, (2) is a frame memo! J.
(3) is a parallel-to-serial conversion circuit, (4) is a CRT, and (1) is a CRT.
) to (4) are the same as in Figure 3, (5) is CPU (1)
This is a 2-bit background selection register set under the control of , and outputs selection signals CO and CI. (6) stores the four types of patterns shown in FIG. Line address RO~ supplied from a timing generation circuit not shown
R2 is a background pattern generator that outputs the dot row of the line; (7) is a parallel-to-serial conversion circuit that converts the pattern output of the background pattern generator (6) into a serial video signal; (8) is a parallel-to-serial conversion circuit. This is an OR circuit that combines the output of the circuit (3) and the output of the parallel-to-serial conversion circuit (7) and supplies it to the CRT (4).

Next, the operation of the apparatus of this embodiment will be explained based on the above configuration.

FIG. 2 is a diagram explaining the operating principle of the background pattern generator (6) of FIG. 1. As shown in the figure, four types of background patterns PO to P3 are stored in the background pattern generator (6) of the apparatus of this embodiment.

Output C of the background pattern selection register (5) shown in FIG.
Depending on the combination of O and CI, one of PO to P3 in FIG. 2 is selected. RO to R2 shown in FIG. 2 are line addresses indicating the lower three bits of the line address of the CRT, and a dot row in the background pattern selected based on this value is output.

For example, if it is not desired to display the background, the CPU (1) sets "0" to the background pattern selection registers CO and C1. When CO-"0" and CI-"0", the background pattern generator selects the PO pattern shown in FIG. 2, so the background is not displayed. This time, CPU (1) sends CO-“1” to the background pattern selection register.

When C1-“B” is set, the P3 pattern is read out from the background pattern generator (6) and the P3 pattern is displayed on the CRT screen.
The pattern is the drawing pattern of frame memory (2) and O
The signals are synthesized by the R circuit (8) and displayed on the CRT (4).

[Effects of the Invention] As described above, according to the present invention, since the background pattern is selected and read out from the background pattern generator and displayed on the CRT, it is possible to instantly change the background, etc. effective.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a display device according to an embodiment of the invention, and FIG. 2 is a diagram illustrating the operation of the display device according to an embodiment of the invention. Figure 3 is a diagram of a conventional display device. In the figure, (1) is the CPU, (2) is the frame memory, and (3) is the CPU.
) and (7) are parallel-serial conversion circuits, (4) is a CRT, , (
5) i; is the background selection register, (6) is the background pattern generator, and (8) is the OR circuit.

Claims (1)

[Claims] Central processing means and memorize figures etc. as dot images,
a frame memory that is updatable and has readout means;
A background selection register controlled by the central processing means, a background pattern generator that generates a predetermined dot pattern selected by the background selection register, and an output of the frame memory and an output of the background pattern generator are combined. A display device comprising: means for converting into a video signal.