JPS61170783A - 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 technology and a technology that is particularly effective when applied to display control for a raster scan type display device, for example in a graphic display system such as a personal computer. This article relates to techniques that are effective for vertical enlargement and scroll display control.

[Background Art] A personal computer equipped with a raster scan type CRT display device and having a graphic image processing function is configured by, for example, a system as shown in FIG.

That is, this system consists of a personal computer main body 10 and peripheral devices (11, 12, 13).
(referred to as U) 1, a system ROM (read-only storage device) 2 in which the system program is stored, a working RAM (a storage device that can be read and written at any time) 3, which serves as a work area and text area when the CPU works.
CR1 A video RAM 4 such as a refresh memory or frame buffer that stores display data displayed on a display device, and a CRT that writes and reads display data in the video RAM 4 based on instructions from the CPUI.
Controller 5, parallel-to-serial converter 6 and l10 (input/output interface) 7 that form and output a video signal based on display data read out from video RAM 4.
It is composed of etc. The respective circuit blocks are connected to each other via a bus 8 consisting of an address bus, a data bus, and a control bus.

The personal computer main body 10 is provided with input operations using a CRT display device 11 that performs display operations according to the video signal output from the parallel-to-serial converter 6, an external storage device 12 such as a floppy disk device, and a keyboard. Peripheral devices such as device 13 are connected.

Conventionally, in the above-mentioned graphic display system, when providing a function to enlarge and display displayed characters or figures in the horizontal direction, the video R is
It is possible to perform enlarged display in the vertical direction without rewriting the display data in AM4.

Therefore, conventionally, as shown in FIG. 5, a register 21 that holds an expansion coefficient supplied from the CPU, a counter 22 that performs counting according to the coefficient set in this register, and a counter 22 that performs counting according to the coefficient set in this register, and a A raster/display address control circuit 23 for supplying a control signal to the display control circuit 20 to repeatedly output a display address for the same raster is provided within the CRT controller 5 in FIG. It was expanding.

This makes it possible to use a simple additional circuit and still have it inside the video RAM (7)! ! ″< f −tt * * * * 615
ゞi=a/<ri J speed vertical expansion is possible.

Regarding the above-mentioned graphic display system and CRT controller having a vertical enlargement display function, please refer to Nikkei Electronics J 19 published by Nikkei McGraw-Hill.
May 21, 1984 issue, No. 343, pp. 222-25
It is shown on page 4.

However, according to the above-mentioned vertical enlargement display method, the display data is enlarged without being rewritten, so if you try to scroll (move) the screen in the vertical direction while the screen is enlarged vertically, the movement may occur. becomes awkward. That is, in the above method, since the start address is a unit of display data, when the enlargement ratio is 1, the
), there is no problem since it moves l rasters at a time, but if the magnification is increased to 3 times, for example, the start address jumps by 3 rasters at once, as shown in FIG. 6(B).

Therefore, there is a problem in that the movement in the vertical direction is performed three rusks at a time, making the movement awkward and making it very difficult to see one display screen.

[Purpose of the invention] An object of the present invention is to provide an image display system.

An object of the present invention is to provide a display control technique that allows very smooth scrolling when a scrolling function is added to a vertical enlargement function.

The above and other objects and novel features of the present invention will become apparent from the description of this specification and the accompanying drawings.

[Summary of the Invention] Representative inventions disclosed in this application will be summarized as follows.

In other words, the register that sets the vertical expansion factor is set to 2.
In addition, a detection circuit for the first raster is provided to automatically select the register. , which achieves the above objective of realizing a smooth vertical scrolling function by enabling vertically enlarged characters and figures to be moved vertically in raster units rather than display data units using a simple circuit configuration. .

[Embodiment] FIG. 1 shows an embodiment of a vertical enlargement and scroll display control circuit according to the present invention.

In this embodiment, two expansion coefficient registers 21a and 21b are used to enable vertical expansion coefficients to be set separately for the first raster and other rasters.
and is provided. The contents of these enlargement coefficient registers 21a and 21b are selectively supplied to the zoom counter 22 via a data selector 24.

In addition, in this embodiment, a display address such as a display address outputted to access the video RAM 4 from a display control circuit 5 such as a CRT controller that decodes commands supplied from the CPU and performs drawing processing and display control. A leading raster detection circuit 25 is provided which monitors the signal and detects whether the display control circuit 5 is outputting an address for controlling the display of the leading raster on the display screen. When the leading raster detection circuit 25 detects the leading raster, it switches the data selector 24 using the selection signal φS and sends the contents of the enlargement coefficient register 21b to the zoom counter 22. Furthermore, if the address output from the display control circuit 5 indicates a raster other than the first raster, the selection signal φ from the first raster detection circuit 25 is
By S.

The data selector 24 uses register 2 instead of register 21b.
The enlargement coefficient in Ia is sent to the zoom counter 22.

The zoom counter 22 is, for example, the enlargement coefficient register 2.
It is composed of a comparison register that holds the vertical expansion coefficient loaded from 1a or 21b, and a counter that counts up to a count value corresponding to the expansion coefficient.

The raster/display address control circuit 23 outputs a display address for repeatedly reading out display data regarding the same raster from the video RAM until the count value in the zoom counter 22 matches the enlargement factor loaded in the comparison register. A control signal is formed and supplied to the 1 display control circuit 5.

The display control circuit 5 includes a raster/display address control circuit 23 (1). ,,□94o□I□OR, TUYU, J formation is performed and supplied to the video RAM 4, and display data is read.

Each of the circuits 21a', 21b to 25 is connected to the above and <C
An external display control circuit 5 such as an RT controller may be configured as a circuit, or may be incorporated inside the CRT controller.

Next, an example of a specific display control procedure in the vertical enlargement and scroll display control circuit configured as described above will be explained using the flowchart of FIG.

In addition, before performing vertical enlargement and scroll display using the above control circuit, the host CPU (see Fig. 4)
, appropriate vertical expansion coefficients ZleZ2 (usually 2.≧
22) is set.

When the control circuit receives a command from the CPUI, it decodes it and first performs initial settings for the entire display screen (
FIG. 3 Step Sl).

Next, it is determined whether the display is to start or not (step S2), and the process waits while repeating step S2 until it is determined that the display has started. If it is determined that one display has started, the process proceeds to the next step S3, and it is determined whether or not the first raster of one display screen is to be displayed. Here, if it is determined that the first raster is to be displayed, the content Z2 of the enlargement coefficient register 21b is loaded into the comparison register in the zoom counter 22 (step S4).

Thereafter, control of the display address in the horizontal direction is started (step S5), and it is determined in the next step S6 whether or not the control of the display address in the horizontal direction has been completed. If the horizontal display address control has not been completed, the process returns to step S5 to execute the display address control, and the operations of steps S5 and 86 are repeated until the display address control is completed.

When the display address control in the horizontal direction for the - raster is completed, the process advances to step S7, and it is determined whether or not the display address control for the entire display screen, that is, all rasters, has been completed. Here, if it is determined that it has not finished,
Proceeding to step S8, for example, by checking whether the count value of the zoom counter 22 matches the enlargement coefficient loaded in the internal comparison register, the enlargement display control for the - raster display data is completed. Determine whether or not.

If the enlarged display control has not been completed, the process advances to step S9, where the contents of the zoom counter 22 are incremented. Then, return to step S5 and step S5
．． S6. S7. S8. Repeat the operation of S9. While repeating this operation, when the count value of the zoom counter 22 matches the expansion coefficient inside the comparison register,
It is determined that the enlarged display control has ended, and the process jumps to step SIO to reset the zoom counter 22.

Thereafter, the process returns to step S3 and it is again determined whether or not it is the first raster on the display screen, and if it is determined that it is not the first raster, the process jumps to step Sll. Then, instead of the expansion coefficient register 21b, the contents z of the register 21a
1 is loaded into the comparison register in the zoom counter 22, and then the process proceeds to step S56.Therefore, from then on, until it is determined in step S7 that the display control of the entire screen has been completed, the magnification coefficient register 21a is loaded with Z1. and repeat the same operation as above. Then, when it is determined in step S7 that the display control of the entire screen has ended, the series of control operations is ended.

According to this embodiment, for example, the expansion coefficient Z1 corresponding to the expansion rate "3" is stored in the expansion coefficient registers 21a and 21b, respectively.
Assuming that pZ2 is set.

Each display data of the first raster and other rasters is repeatedly displayed three times each.

Therefore, for example, display 1 data rAJ and rBJ as shown in FIG. 6(A) are displayed as being enlarged three times in the vertical direction as shown in FIG. 2(A).

In addition, if the expansion factor register 21b is first set to the expansion rate "2" and the register 21a is set to "3" as above, the display data will be displayed at the beginning, as shown in FIG. 2(B). Only for the raster, 2 times 1°-1e #kL A 1.3 Ka 1o Yuka Awa □ 47- is performed.

Similarly, the setting value Z1 of the expansion coefficient register 21a is left as is, and the content Z2 of the register 21b is set to "1" first.
If set to , only the rasters other than the first raster will be displayed enlarged three times as shown in FIG. 2(C).

Therefore, according to the control flow shown in FIG. 3, each time the display of one screen or several screens is completed, the expansion coefficient register 21b
The set value Z2 is decreased in order as r3J, r; IJ, rl'' using the CPUI or display control circuit 5, and after ``1'', the value is changed from S to S+α (α is the memory width). and change it to the address of the next display data. In this way, Figure 2 (A) → (B) → (C)
→As the display changes as shown in (D), each dot shown in black in one drawing appears to disappear upwards from the screen.

As a result, when performing an enlarged display as shown in Figure 6 (B) using the conventional method, scrolling could only be done in display data units, which caused awkward movement, but vertical scrolling in raster units is now possible. This makes the movements smoother and the screen much easier to see.

If you want to scroll the display screen downward in the opposite way to the above, increase the contents of the expansion coefficient register 21b for each screen in sequence, and decrease the start address like S-α. Just do it like this.

Note that in the above embodiment, the case where one display screen is controlled by one display device has been explained, but if you want to display multiple split screens on one display screen, the The circuit block 2 as shown in FIG.
1a, 21b to 25, and if display control is executed according to the control flow shown in FIG. 3 for each split screen,
In multi-window display control, vertical enlargement and scrolling can be performed for each split screen.

[Effect] Two registers are provided to set the vertical expansion coefficient,
In addition to being able to set the expansion factor for the display data of the first raster separately from the expansion factors of other rasters,
Since a detection circuit for the first raster is provided to automatically select the register, vertically enlarged characters and figures can be moved vertically in raster units rather than display data units with a simple circuit configuration. This effect has the effect that a smooth vertical scrolling function can be realized by adding a simple circuit and without increasing the burden on software.

Although the invention made by the present inventor has been specifically explained above based on Examples, it goes without saying that the present invention is not limited to the above Examples and can be modified in various ways without departing from the gist thereof. Nor. For example, in the above embodiment, two enlargement coefficient registers 21a and 21b, each of which can set an enlargement coefficient separately, are provided to realize a vertical school function. In addition, it is also possible to control the display of characters and figures by partially changing the vertical enlargement ratio.

[Field of Application] The above description mainly describes the application of the invention made by the present inventor to a CRT controller or its external circuit in a graphic display system equipped with a CR1 display device, which is the field of application that forms the background of the invention. However, the present invention is not limited thereto, and can be used in general systems having raster scan type display devices.

For example, it can be used in a system using a dot matrix type liquid crystal display device. In this raster scan method, individual display data is not sequentially supplied to display devices within one raster period as in the CR1 display device, but one raster's worth of display data is used as a signal retainer such as a shift register. Output from the circuit in parallel, and the parallel signals are simultaneously supplied to the display device.
−

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of a vertical enlargement and scroll display control circuit according to the present invention. Explanatory diagram showing the effect when scrolling and scrolling, Part 3
The figure is a flowchart showing an example of a display control procedure by the display control circuit of this embodiment. 4 is a block diagram showing an example of a graphic display system in which the vertical enlargement scroll display control circuit according to the present invention is used; FIG. 5 is a block diagram showing an example of a conventional vertical enlargement scroll display control circuit; FIG. 4 is an explanatory diagram showing the effect when the M-th circuit performs three times vertical enlargement and scrolling. ■・・・CPU (microprocessor), 4...
- Video RAM, 5... Display control circuit (CRT controller), 6... Parallel-serial converter, 10. . °°Graphic display system (personal computer), 11...CR1 display device, 12...external storage device, 13...input operation device, 21.21a
, 21b...Enlargement coefficient register, 22...Zoom counter, 23...Raster/display address control circuit, 24...Selector, 25...Start raster detection circuit. /-ゝ, Agent Patent Attorney Katsuma Ogawa (\,-1/ Figure 1 Figure 2 (A)
(Bn (C) (D) Figure 3 Figure 4

Claims (1)

[Scope of Claims] 1. A display control device that forms and outputs display addresses for sequentially reading display data for a raster scan type display device from a predetermined memory, the display control device comprising: a vertical enlargement factor on a display screen; It has two registers that can be set, and a counter that performs counting corresponding to each expansion factor in these registers, and displays data related to the same line or raster a number of times according to the expansion factor in each register. A display control device characterized in that vertical enlarged display and scrolling are made possible by forming display addresses to be read. 2. A patent characterized in that it comprises a circuit for detecting the first raster on a display screen, and a selector capable of selectively supplying the contents of the two registers to the counter based on the output signal of this circuit. A display control device according to claim 1.