JPS5895387A - Picture memory control system for character display - 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 When the contents of the screen of a character display device are scrolled up and down line by line, the present invention effectively uses the screen memory and allows a part of it to be used for other purposes. ) This relates to a screen memory control method.

Conventionally, in a character display device, the contents of a screen are moved line by line upward or downward on the screen. A so-called scroll amplifier or scroll down is performed.

In this method, the character *@td of the screen memory is taken out, the oath is performed again, and the remainder @A is shifted. However, this method takes a long time to execute, so a method of changing the start position of the display address during the vertical interval M(VS) while leaving the contents of the screen memory as is is shown in Figure 1(a). shows the initial state of the screen memory, FIG. 2B shows the position of the start address when scrolled up by one line, and FIG. 1C shows the position of the start address when scrolled up by two lines. 80 characters per line, 80 characters x 2 to display on one screen with 24 lines
It is 4 lines - 1920 characters, but the image memory is 2
Uses 048 bytes of memory. Therefore 2048~
1920=128 bytes are indicated by the remainder, all "0"
It becomes gummy memory and is not used effectively.

Figure (b) shows the star (
2) The start address is entered at address "80", and the rest are addresses "2000-2047" and 0-79'. Similarly, in the same figure (C), when scrolling up two lines, the start address is enters address "160" and the rest are addresses "62-159".

For example, when controlling using an MPU, a register is required to store the cursor status and intermediate progress other than data, but at present, a separate RAM is provided. In this case, it would be efficient if the remaining 128 bytes of screen memory could be used for this purpose. However, as mentioned above, this occurs irregularly depending on the number of scroll-up lines, so it is difficult to use them all at once.

SUMMARY OF THE INVENTION An object of the present invention is to provide a screen memory control method that can effectively utilize the surplus generated in the screen memory when scrolling the screen of a character display device.

In order to achieve the above objective, the control method for the screen memory of ``Full ψ'' scrolls the contents of the character screen up or down line by line, so a display character counter is provided to access the screen memory (6), In a character display device that sets and counts a start address according to the movement of a line, means is provided for storing an initial address of a specified line in the screen memory, and the initial address is set in the display character counter, The present invention is characterized in that a predetermined storage area below the initial address is scrolled, and other areas are used for other purposes.

The present invention will be described in detail below with reference to examples.

FIGS. 2(a) to 2(C) are diagrams explaining the principle of the present invention.

The figure (a) shows the initial state of the 1i1111fi memory, the figure (b) shows the case of scrolling up one line, and the figure (C) shows the case of scrolling up two lines, corresponding to figures 1 (,) to (Q). It is something. In other words, as shown in the figure, when scrolling between Figure 1 and Colleague, there is a surplus of 128 bytes, so the area from address 0 to 127 on one side is set as an unused area for work. Then, in the area below the initial address of address ``128'', the first line is the address ``128~207'', and the second line is the address ``208~''.
(4) 287°', etc. 80 characters per line x 24
Line = 1920 characters are completely stored.

Then, endless scrolling is performed only in this area. In the figure (a), the initial address and the start address are the same address "128" in the initial state, but in the figure (b), as a result of scrolling up, the start address is shifted by one line and becomes the address "208". The 24th line is then moved up. In the same figure (C), the start address is shifted by two lines to the address "288", and is further moved up to the 26th line. (Just before or after scrolling up, set the memory to 0" for the number of scroll-up lines.) In this way, the upper limit of the storage area below the initial address.

Since scrolling is performed endlessly between the lower limits and the other areas are irrelevant, in this case, addresses "0 to 127" can be used for other purposes regardless of the number of scroll lines.

FIG. 6 is an explanatory diagram of the configuration of an embodiment of the present invention according to the above-described principle.

In the same figure, the external (host, keyboard, etc.) Continuation or writing is performed. At the time of display, the character code read out from the screen memory 1 by the display character counter 7 is converted into a character image signal by a character generator (CG) 3 via a line buffer 2 for each line, and then sent to a display control circuit 4. is displayed on the display unit 5 via.

The main part of the present invention has a configuration including the MPX 6 and below, which supply the screen memory 1 with a start address and an initial address in the case of scrolling as explained in FIG.

Conventionally, as multiple lines are moved up and down by scrolling, a start address is set in the start address register 8, and the address shifted for each line of scrolling is sent to the display character counter 7, from which the number of characters per line is calculated. is counted, and the corresponding address is switched by the MPX 6 and sent to the screen memory 1, where the data is read. As can be seen in FIG. 1, as a result of scrolling up, the 24th line reads and displays the data next to the 23rd line. Because of (6), the margin changes due to scrolling.

On the other hand, in the present invention, in order to set the initial address of the area to be scrolled, that is, the address "128" in FIG. Set the initial address when moving to a special location that is shifted by a few minutes.

In the case of FIG. 2(a), that is, in the initial state without scrolling, the initial address and start address are set as the same address "12B" in the display character counter 7, and the entire screen memory 1 of the MPX6 is accessed. On the other hand, in (b) and (0) of the same figure, the initial address remains at address ``128'', and the start address is set to address ``208'' and ``288'', respectively, and the count of display character color/7 is set. It is done. As a result of scrolling up in this way, the 24th line in the figure (b) is the data above the 1st line, and the 24th and 23rd lines are the data above the 1st line in the figure (c).
Read and display the data above the row. Just before or after scrolling up, add the scroll alarm (7) by the number of lines you want to scroll up. In this case, the address "0~
127'' is completely irrelevant regardless of whether there is scrolling or not, so it can be used as the t register for other purposes such as recording the cursor position or the status of the progress of processing. Can be omitted.

As explained above, according to the present invention, when scrolling 1m'i of the screen of a character display device, means for storing the initial address of a designated line in the screen memory is provided, and a predetermined storage value below this initial address is provided. This allows only the area to be scrolled, and the remaining area can be used for other purposes. In this way, the screen memory can be used for efficient scrolling, and can also be used as a register used in the middle of processing, which greatly contributes to saving on memory means.

[Brief explanation of the drawing]

Figures 1 (a) to (0) are diagrams of )jAmm of the conventional example, Figures 2 (a) to (C) are diagrams explaining the principle of the present invention, and Figure 6 is a diagram explaining the configuration of the embodiment of the present invention. In the figure, 1 is the screen memory, (8) 2 is the line buffer, 3 is the character generator, 4 is the display control circuit, 5 is the display section, 6 is the multiplexer, 7 is the display character counter, and 8 is the start. Address register 11 indicates an initial address register. Patent applicant Fujitsu Limited sub-agent Patent attorney 1) Yoshishige Saka (9)

Claims (1)

[Claims] In order to scroll the contents of a character screen upward or downward line by line, a character display device is provided with a display character counter that accesses the screen memory, and sets and counts a start address according to the movement of lines due to scrolling. Means for storing an initial address of a designated line of the screen memory is provided, the initial address is set in the display character counter, and a predetermined rated mesh area below the initial address is scrolled; A screen memory control method for a character display device, characterized in that an area other than the area other than the original area is used for another purpose.