JPH0573023A - Display controller - Google Patents

Abstract

PURPOSE:To make a display controller comply with centering processing in accordance with the number of lines automatically or by the use of a program even in the case of display having optional resolution by varying the number of display starting lines. CONSTITUTION:This controller is provided with a display starting line register 1 for setting the number of display starting lines, an application soft display line number register 2 which stores the number of lines actually displayed, a screen vertical direction counter 4 which counts the number of vertical lines, a display line starting control circuit (display starting line calculation part) 7 which decides the display starting line based on output from the register and the counter, and a comparator 6 which compares the display line starting value of the circuit 7 with the counted value in the vertical direction of the counter 4 and outputs a display starting signal, and constructed so that the display starting line is not fixed but variably set. Namely, centering processing is executed automatically or by the use of the program even in the display having the optional number of lines.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display controller suitable for use in a personal computer.

[0002]

2. Description of the Related Art Recent advances in semiconductor technology have made it possible to supply microprocessors, peripheral control LSIs, memory LSIs, etc. at a very low cost. I can do it. Further, in the field of personal computers, a laptop type, which is small, lightweight, and convenient for carrying, has been in widespread use in place of the conventional desktop type. The display device that the laptop type has,
Flat panel displays such as liquid crystal displays and plasma displays are often used. The display device which is the core of the man-machine interface is required to have more and more advanced functions, and high resolution and multicolor display are typical examples. Therefore, not only this but also a controller chip for controlling it is required to be multifunctional. For example, the resolution starts from 640 * 200 and ends at 640 * 3.
50, 640 * 400, 640 * 480 and the tendency of expansion.

Normally, when an application program is executed, the number of display lines suitable for the execution environment of the software is set in a predetermined register incorporated in the display controller, and the number of display lines on the display is determined. Now 4
When operating software compatible with 350 line (640 * 350) display on a plasma display of 00 line (640 * 400) display, the number of lines increases by 50 lines. This can be handled by displaying only 350 lines. Also, other limited combinations of lines (400 → 480, 350 →
480) can be handled by doing the same. However, when the number of display lines is changed from the largest to the smallest (the reverse of the above combination), the first line of the screen becomes the display start line, and the display lines exceeding the maximum number of lines are not displayed. In order to display the display area in the center of the screen by using the above method, the area newly set as blanking is equally distributed to the top and bottom of the screen. These methods are called centering processing methods.

[0004]

The above-described conventional centering processing is flexible and flexible in that it can handle only a limited number of display lines such as 350, 400, and 480 lines, and cannot handle a larger number of display lines. I lacked sex.

The present invention has been made in view of the above circumstances, and the conventional centering process can be performed only for a display having a limited number of lines, whereas the number of display start lines is variable. With this function, centering processing according to the number of lines can be handled automatically or by a program even for displays with arbitrary resolution, and in the case of manual operation, the display area is moved to the blank area of the screen by the set number of lines. An object of the present invention is to provide such a display control device.

[0006]

A display control device according to the present invention is set with a counter that counts the number of lines in the vertical direction of a screen that configures a display and a parameter set by an application program to set a display start line value of a screen display area. Centering process that starts the display operation by a register that is compared with a register that sequentially compares the register value and the counter value, and the match detection by this comparator, and starts the display from an arbitrary line position on a display having an arbitrary resolution. And a circuit. Further, a counter for counting the number of lines in the vertical direction of the screen which configures the display, a register for indicating the number of display lines set by the application program, a register for indicating the total number of lines that the display can display, and the above two Depending on the value indicated by the register,
An arithmetic circuit for calculating the display start line value so that a screen area corresponding to the number of display lines set by the application program is displayed in the center of the display, and the number of lines calculated by this circuit is compared with the counter value. A comparator and a centering circuit that performs centering processing on an arbitrary line position according to the number of display lines set by an application program for a display having an arbitrary resolution by detecting a match with this comparator may be provided. Characterize. In this case, the arithmetic circuit calculates (L−N) / 2 based on the number of lines N set by the application program and the total number of lines L that can be displayed on the display.
Is calculated and output.

[0007]

According to the present invention, as described above, the number of display start lines is set in the register or pin, the register or pin for storing the number of lines to be actually displayed, and the counter for counting the number of vertical lines are provided. While the display start line is fixed in the conventional centering process by the display line start control circuit that determines the display start line and the display circuit that receives the signal and performs display,
This can be set variably, and even if the display has an arbitrary number of lines, the centering process can be performed automatically or by a program, and in the case of manual processing, the number of lines is set if a blanking area is set on the screen. Only the display area can be moved within the screen. The automatic centering process is the process of automatically calculating the display start line to set the display area in the center of the screen for any display and setting the display area on the screen.In the case of manual operation, the display starts in the register. Write line and set display start line directly.

As a result, conventionally, the centering process is performed in a specific line interval (350 to 400, 400 to 4).
According to the present invention, centering processing can be realized even between arbitrary lines, while the processing of only 80) can be performed.
It is possible to move freely by the number of lines set as the blanking area.

[0009]

1 is a block diagram showing an embodiment of the present invention.

In the figure, reference numeral 1 is a register for storing a display start line, and reference numeral 2 is a register for storing the number of lines to be actually displayed, which are set by an application program. Reference numeral 3 is a register in which the number of displayable lines of the flat panel display is set and stored. Reference numeral 4 is a counter for counting the number of lines in the vertical direction of the screen.

Reference numeral 5 is a multiplexer, and selects which of the registers 1 and 2 is input to the comparator circuit 6 described later. Here, it can be realized either automatically or manually, and any one is selected.

Reference numeral 6 is a comparison circuit, which compares the display line start value with the vertical counter value and outputs a display start signal. Reference numeral 7 is a display start line calculation circuit, which calculates the display start line value from the line value set by the software and the display line value. FIG. 2 is a diagram cited to explain the operation of the embodiment of the present invention, and is a diagram showing the correspondence between the number of lines on the screen and the display lines.

The operation of the embodiment of the present invention will be described in detail below. The embodiment shown in FIG. 1 causes a display monitor having an arbitrary number of lines to perform a centering process by automatically generating a line value of a display start as a signal by a program or the like and outputting the signal to a centering processing circuit. It is a thing. The display start line control will be described below for each of the program processing and the automatic processing. First, the case of processing by a program or the like will be described. The value indicated by the counter 4 indicating the number of lines in the vertical direction of the screen and the value of the display start line register 1 selected at the time of setting by the program by the multiplexer 5 are compared by the comparator 6.
By sending the comparison result to the display start signal centering processing circuit (not shown), the display can be started from an arbitrary line position. This makes it possible to move the display area in the screen by the number of lines newly set as blanking by the above centering processing. Next, the case of automatic processing will be described. Based on the value of the display line number register that stores the number of lines to be actually displayed, which is indicated by the register 2, and the value of the flat display register 3 that stores the number of lines of the flat display, the display start line calculation circuit 7 The display start line is calculated, the value is selected as “automatic” by the multiplexer 5, and the value is compared with the value of the counter 4 for counting the vertical direction of the screen by the comparator 6. A display start signal is generated according to the comparison by the comparator 6, and a centering process is performed. Further, the display start line calculation circuit 7
A function to adjust the number of lines from the first line of the screen to the [display start line -1] (hereinafter referred to as the upper blank area) and the number of lines from the [display end line +1] to the last line as follows: To have. That is, the number of blanking lines is L, the number of screen lines is W, and the number of display lines is N.
, L = (W−N) / 2. In the case of manual processing, L is arbitrary. This means that the line address at which display should be started can be set at an arbitrary position, and the display area is prevented from exceeding the maximum number of lines when the screen is moved.

[0014]

As described above, until now, the centering processing has been performed in a specific line interval (350 to 400, 400).
To 480), the centering process can be performed between arbitrary lines by the above-described functional configuration of the present invention, and the line can be freely moved by the number of lines set as the blanking area. it can. As a result, it is possible to realize a system construction that is highly expandable and flexible.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a diagram showing the correspondence between the number of lines on the screen and the display lines, which is cited for explaining the operation of the embodiment of the present invention.

[Explanation of symbols]

1, 2, 3 ... Register, 4 ... Counter, 5 ... Multiplexer, 6 ... Comparator, 7 ... Display start line control circuit.

Claims (3)

[Claims] 1. A counter for counting the number of lines in the vertical direction of a screen which configures a display, a register for setting a display start line value of a screen display area by a parameter set by an application program, and the register value and the counter value. Display control characterized by comprising a comparator for successive comparison, and a centering processing circuit for starting display operation by detection of coincidence by the comparator and starting display on an arbitrary line position on a display having an arbitrary resolution apparatus. 2. A counter for counting the number of lines in the vertical direction of the screen, which constitutes a display, a register for indicating the number of display lines set by an application program, and a register for indicating the total number of lines that the display can display. An arithmetic circuit for calculating the display start line value so that a screen area corresponding to the number of display lines set by the application program is displayed in the center of the display by the values indicated by the above two registers, and the arithmetic circuit A comparator that compares the number of lines with the counter value, and a centering circuit that performs centering processing at an arbitrary line position according to the number of display lines set by an application program for a display having an arbitrary resolution according to the detection of coincidence by the comparator. And comprising Display controller. 3. The arithmetic circuit calculates and outputs (L−N) / 2 based on the number of lines N set by an application program and the total number of lines L that can be displayed on a display. The display control device described.