JPH0112309Y2 - - Google Patents

Description

[Detailed description of the invention] [Technical field to which the invention pertains] The present invention facilitates the display of a part of a figure displayed on a graphic display by filling it with various rectangular patterns. The present invention relates to a pattern generation circuit that generates a signal that can be used in various ways.

[Description of the Prior Art] In recent years, there have been an increasing number of devices that use CRT (Cathode Ray Tube) display devices to display various figures. Sometimes you may want to write a simple pattern or erase only a part of the screen. Conventionally, in such cases,
First, the entire screen is erased, and then a vector generator or CPU is used to write or erase only the necessary areas. However, the above-mentioned means have the following problems.

In order to write a simple pattern to a part of the displayed screen, it is preferable to have the CPU or vector generator perform the calculation processing because it limits the advanced functions of these devices to simple tasks. do not have.

If a CPU or a vector generator is used to generate the above pattern, it takes a long time to generate the pattern, which is undesirable.

[Purpose of this invention]

The present invention solves these problems, and its purpose is to attach any part of the CRT screen (the shape of this part means a rectangle parallel to the X and Y axes) as shown below. An object of the present invention is to provide a pattern generation circuit that can generate patterns at high speed.

(1) Completely erase the rectangular area (see a in Figure 1) (2) Fill in the entire rectangular area (see b in Figure 1) (3) Apply a stripe pattern to the rectangular area (see c in Figure 1) [ Overview of the present invention] The present invention consists of a pattern register that inputs a multi-bit pattern signal forming part of a desired generation pattern from the CPU and temporarily stores it, and a pattern register that stores the contents of the pattern register in the next stage of the video.
It is equipped with a counter that takes out the address signal for writing to the RAM, and repeatedly reads out the multiple bit signals written to the pattern register, and arranges the contents on the video RAM so as to connect them to create the desired rectangular generation pattern. This allows the CPU to be used efficiently until the video is formed on the video RAM.

[Explanation based on examples]

The present invention will be explained in detail below using the drawings.

FIG. 2 is a diagram showing an example of the configuration of a graphics device including an example of a pattern generation circuit according to the present invention. In the figure, numeral 1 denotes a computer (hereinafter simply referred to as CPU), which controls the operation of the entire graphics device. 2 is a keyboard, which specifies the position and size of any rectangle on the CRT. 3 is a pattern generation circuit according to the present invention, which is the circuit shown by the dashed line in FIG. 4 is a pattern register, which sends signals from the CPU 1 to the data bus to realize the pattern to be displayed within the rectangle specified above.
It is introduced via _D1 and temporarily stored in memory. Reference numeral 5 is a start address register, which is a register for storing position data of a rectangle designated by the keyboard 2. Reference numeral 7 denotes a stop address register, which stores the position data of the rectangle designated by the keyboard 2. Here, the data stored in the start address register 5 is an address representing X ₁ and Y ₁ of point P ₁ shown in FIG.
The data to be stored in memory is X ₂ at point P ₂ shown in Figure 3,
This is an address representing Y ₂ . The contents of FIG. 3 will be described later. 9 is a counter which receives a clock signal CLK from a predetermined circuit (not shown) of the graphics device, and counts up the data loaded from the start address register 5 by one each time this signal CLK is input. be. Comparators 11 and 12 compare the addresses X ₂ and Y ₂ of the point P ₂ with the data from the counter 9, respectively, and output an end signal END when they match. 13 is video RAM;
It stores the data to be displayed on the CRT screen. 15 is a CRT, which is a display device.
The operation of the graphic device shown in FIG. 2 constructed as above will be explained below with reference to FIG.

FIG. 3 is a diagram showing the concept of a video RAM and its relationship with a CRT screen, and can be used to explain the outline of the operation of a graphics device using the present invention. In FIG. 3, the numbers assigned to each component are the same as those in FIG. 2, and elements with the same number represent the same component. usually,
In a CRT device, the CRT screen corresponds to the contents of the video RAM.

Here, in a graphics device using the present invention, if you want to completely fill in rectangle B on the CRT screen, for example, you can use the cursor to
Specify points P ₁ and P ₂ that represent the position and size of the part.
This specification can be made using keyboard 2, for example.
Data can be input to the CPU 1, and data is written to the video RAM 13 via the pattern generation circuit 3 according to the present invention in order to fill in portion B as shown in FIG. Then, a diagram with portion B filled in is displayed on the CRT screen according to the contents of this video RAM.

The above is the operation of the graphics device using the present invention. Below, the operation of the pattern generation circuit according to the present invention will be explained using FIG. 2.

First, as described above, use the keyboard 2 or the like to specify the area on the CRT screen that you wish to display as shown in FIG. Coordinate data of points P ₁ and P ₂ representing this designated area and data for selecting which pattern from a to c in FIG. 1 are input to the CPU 1. In accordance with this input data, the CPU 1 sends the raster in the first column of part B to the pattern register 4 via the data bus D ₁ (whichever raster is selected from a to c in FIG. 1 from the keyboard 2). Write the data corresponding to the corresponding pattern). In this embodiment, the number of data that can be written into the pattern register 4 is 20 bits.

On the other hand, the generation pattern that this invention aims to obtain is the pattern shown in Figure 1, and all of these patterns can be seen as repeating patterns in the horizontal direction (a and b in Figure 1 are considered to have no pattern). I can do it. Therefore, by writing a portion of this repeated pattern into the pattern register 4, reading it out many times and sequentially connecting it on the video RAM 13, each generation pattern shown in Figure 1 can be formed. .

On the other hand, point P ₁ is in the start address register 5.
The address (X ₁ , Y ₁ ) of point P 2 is written to the stop address register 7, and the address (X ₂ , Y ₂ ) of point P ₂ is written to the stop address register 7.
is written. Then, when the pattern generation circuit is activated, the clock signal CLK output from a predetermined circuit (not shown) of the graphics device is
Applied to counter 9. The counter 9 operates to increment the value of the start address signal introduced from the start address register 5 by one each time a pulse of the clock signal CLK is applied. Therefore, the output signal of this counter 9 corresponds to the address of data to be written into the video RAM. And this clock signal CLK
The contents of pattern register 4 are displayed in synchronization with the video
Written to RAM13. The address written at this time is the address indicated by the output signal of the counter 9.

In this way, each time the clock signal CLK is applied, signals representing patterns are successively read out from the pattern register 4 into the video RAM 13. Then, when the 20-bit data of the pattern register 4 is transferred to the video RAM 13, the data is repeatedly transferred to the video RAM 13 starting from the first bit of the pattern register. Since the pattern shown in Figure 1 is a repeating pattern, the contents of pattern register 4 are read out many times and video RAM 1 is
3, the generation pattern shown in FIG. 1 can be formed.

In other words, CPU 1 once transfers data to pattern register 4.
Once 20-bit data is written, the contents of pattern register 4 will be repeated over and over again.
Until the desired rectangular pattern is formed on the video RAM 13 after reading to the RAM 13,
Since other arithmetic processing and the like can be performed, it is possible to operate efficiently. This point is one of the major effects of the present invention.

In this way, data is written one after another into the area B of the video RAM 13 shown in FIG. When the output signal of the counter 9 matches the value (X ₂ , Y ₂ ) of the stop address register 7, the end signal END is sent from the comparators 11 and 12.
is output, and all the data necessary to represent the rectangle B portion has now been written.

Thereafter, the contents of the video RAM 13 are displayed on the screen of the CRT 15 using known techniques.

As a result of the above, the desired rectangular part a in Fig. 1 is displayed on the CRT15 screen as shown in Fig. 3.
It can be displayed in any pattern of ~c.

In the above explanation, the start address is first set in the counter 9, and the count is incremented from this data every time the clock signal CLK is applied.However, contrary to this operation, the stop address is first set in the counter 9. The present invention also works if the clock signal CLK is set and counted down from this data every time the clock signal CLK is applied. Of course, in this case, one of the data (reference data) compared by the comparators 11 and 12 is the data of the start address.

[Effects of this invention]

As described above, according to the present invention, the following effects can be obtained.

Since the start address and stop address are specified, only the necessary parts are operated on, which speeds up the processing.

Several types of patterns can be generated by the pattern register (roughly divided into three types shown in FIG. 1).

It can reduce the workload of the CPU and allow faster processing.

[Brief explanation of the drawing]

Figure 1 is a diagram illustrating the types of patterns that are to be rewritten in a rectangular area on a CRT screen, and Figure 2 is an example of the configuration of a display device using the present invention. Figure shown, 3rd
The figure shows the relative relationship between the video RAM and the CRT screen. 1...CRT, 2...Keyboard, 3...Pattern generation circuit, 4...Pattern register, 5...
Start address register, 7... Stop address register, 9... Counter, 11, 12...
Comparator, 13... Video RAM, 15...
CRT.

Claims (1)

[Claims for Utility Model Registration] A circuit used in a graphics device includes a pattern register 4 capable of storing a plurality of bit signals, registers 5 and 7 storing data of a start address and a stop address, and registers 5 and 7 capable of storing data of a start address or a stop address. A counter 9 that inputs data from either the stop address and counts up or down for this data, compares the data from the start address or stop address with the data from the counter, and outputs an end signal when they match. a multi-bit pattern signal forming a part of a desired rectangular generation pattern is written in the pattern register, and the contents of the pattern register are repeated using the output of the counter as an address signal. A pattern generation circuit that reads and transfers to the next stage (viteo RAM).