JPH04295926A - Screen display device - Google Patents

Abstract

PURPOSE:To increase the speed of a screen scrolling process by providing a means which starts scanning for a screen display at an optional address in a screen data area. CONSTITUTION:A screen address calculating circuit 4 calculates a screen address on a display from the register values of an AMIN register 8, an AMAX register 9, an SS register 7, an SE register 6, and an SC register 5, and screen data obtained from a memory 1 are converted by a screen display circuit 2 into a screen signal, which is displayed on the display. In scroll mode, scrolling operation is performed only by rewriting the SS and SE registers and screen data of one line which appears nearly, thereby speeding up the process.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for displaying screen information stored in a memory on a display.

0002

2. Description of the Related Art A conventional screen display device, as shown in FIG. Display circuit 1
2, the screen data is converted into a screen signal (luminance signal, color signal) for display on the display 13 and displayed. In this conventional screen display device, there is a one-to-one correspondence between the display address 10 and the display position on the display 13.
Referring to the memory map of FIG. 2, the scan start address of the screen display is fixed at AMIN, and the scan end address is fixed at AMAX.

In the conventional screen display device described above, since the display address has a one-to-one correspondence with the display position, when the screen is moved up or down by one line (hereinafter referred to as scrolling), all the information in the memory is There was a problem in that the screen data had to be rewritten to an address moved by one line, which took time to process.

0004

[Problems to be Solved by the Invention] The present invention provides a screen display device that is equipped with means that can start scanning the screen display from an arbitrary address in the screen data area, thereby making it possible to speed up the screen scrolling process. The purpose is to provide.

[0005]

[Means for Solving the Problems] The screen display device of the present invention includes a memory for storing screen data, a screen display circuit for converting the data into a screen signal, and an SC register for indicating the address of the currently displayed screen data. The AMIN register indicates the minimum address value of the area storing screen data on memory, the AMAX register indicates the maximum address value, the SS register indicates the display start address of screen data, the SE register indicates the display end address, and the screen signal. It is characterized by comprising a display for displaying information.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a block diagram of one embodiment of the present invention, and FIG. 2 is its memory map.

[0008] The minimum address value in the memory of the screen data area is stored in the AMIN register 8, and the AMAX
The maximum address value in the memory of the screen data area is stored in the register 9, the address of the screen data at which the screen display scan starts is stored in the SS register 7, and the address of the screen data at which the scan ends is stored in the SE register 6. Then, the address of the screen data corresponding to the display position currently being scanned is entered into the SC register 5, and these AMIN registers 8
, AMAX register 9, SS register 7, SE register 6, and SC register 5 are stored in the screen address calculation circuit 4.
is input. As can be seen from the memory map in FIG.
An area is reserved up to the value of the MAX register 9, and screen display scanning starts from the address indicated by the SS register 7 of the memory map and ends at the SE register 6. The address currently being scanned is indicated by SC register 5, which is incremented after displaying the data of the current address, and when the address value exceeds the value indicated by AMAX register 9, the value of SC register 5 is transferred to AMIN register. 8
is rewritten to the value indicated by . The screen display address is calculated using the value of the SS register 7 as a starting point. Note that the method of writing data to these four registers is omitted from the block diagram because it is not directly related to the present invention.

These calculations are performed by the screen address calculation circuit 4, and the processing shown in FIG. 4 is performed by hardware to obtain screen address data.

The screen data, which is the content of the address indicated by the SC register, is converted into a screen signal by the screen display circuit 2 and displayed on the display at the display position indicated by the screen address obtained by the screen address calculation circuit. With this, screen scanning can be started from any address in the screen data area on memory, and when scrolling the screen up and down, for example, when scrolling up, the contents of the SS register 7 indicating the scanning start address and the scanning The contents of SE register 6 indicating the end address are added for one line and stored in SS register 7 and SE register 6, respectively (however, the addition result is not stored in AMAX register 9).
If the value exceeds the value of AMAX, the amount exceeding the value of AMAX is
(Put the value added to the value in N register 8 into each register). Then, upward scrolling can be realized by writing the screen data of the newly appearing line in the memory area corresponding to one line of the screen display area from the value indicated by the changed SE register 6 to the value indicated by the SS register. In contrast, downward scrolling subtracts one line from SS register 7 and SE register 6, and displays newly appearing screen data in one line of screen display area from the changed value of SS register 7. This can be achieved by writing.

[0011] As a result, although scrolling conventionally required rewriting the entire screen data area, according to the present invention, scrolling can be achieved by simply rewriting one line of screen data, and the scrolling process is simplified. Speed can be improved.

0012

[Effects of the Invention] As explained above, since the present invention can start scanning the screen display from any memory address in the screen data area, it is possible to scroll faster than before. It has the effect of being able to.

[Brief explanation of drawings]

FIG. 1 is a block diagram of one embodiment of the invention.

FIG. 2 is a memory map of FIG. 1;

FIG. 3 is a block diagram of a conventional screen display device.

FIG. 4 is a flowchart showing an algorithm for address calculation by the screen address calculation circuit 4 of FIG. 1;

[Explanation of symbols]

1 Memory 2 Screen display circuit 3 Display 4 Screen address calculation circuit 5 SC register 6 SE register 7 SS register 8 AMIN register 9 AMAX register 10 Display address 11 Memory 12 Screen display circuit 13 Display

Claims (1)

[Claims] Claim 1: A memory that stores screen data, a screen display circuit that converts the data into a screen signal, an SC register that indicates the address of the currently displayed screen data, and the minimum area of the memory that stores the screen data. A screen display device comprising an AMIN register indicating an address value, an AMAX register indicating a maximum address value, an SS register indicating a display start address of screen data, an SE register indicating a display end address, and a display displaying a screen signal. .