JPS62231287A - Display unit - 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] [Purpose of the invention] (Industrial application field) The present invention is a graphic scanning type CRT.

This invention relates to improvements in display devices for displaying characters.

(Prior Art) The basic configuration of this type of display device is as shown in FIG. CRT2 that displays the contents of this memory 1
and a CRT controller 3 that controls the drawing (hereinafter referred to as "drawing") and reading of the display memory 1.

When scrolling up the display screen in this type of display device, for example, as shown in FIG. It is conceivable to do this by setting the start address to, for example, a-+b as shown in FIG. Incidentally, the display screen shown in FIG. 4 shows the case where the successive output start address is b.

By the way, in the above-mentioned scroll-up method, it is necessary to draw the character in the display memory 1 for two erasures that cross the boundary of the display memory 1, as shown in FIG. .

However, in conventional display devices, the display memory 1
The X coordinate when drawing to is specified as a position that is sequentially incremented by 1 from the drawing start address, so if the drawing start address is other than the initial value O, display memory 1
I specified the X coordinate beyond the boundary of display memory 1.
It was not possible to draw in these two areas. Therefore, it was not possible to scroll up the display screen using the method described above.

(Problems to be Solved by the Invention) As mentioned above, when scrolling up the display screen, in conventional display devices, the drawing of characters, etc. in the display memory is performed in a 2f space that straddles the boundaries of the display memory.
This could not be done for tlt.

SUMMARY OF THE INVENTION Therefore, it is an object of the present invention to provide a display device that can draw graphics, etc. even in two areas that straddle the boundary of the display memory, and thereby allows easy scrolling up of the display screen. It is in.

[Structure of the invention] (Means for solving the problem) The present invention provides M (x=0 to M-1) XN (y=0-
A display controller that controls drawing in the display memory of M-1), an X address generating section that outputs an
=
and an X coordinate control section that outputs information to be set to the drawing processor.

(Function) When the x coordinate determined based on the drawing command and output from the X address generation section is input to the address conversion section, it is converted into a continuous number of physical addresses and the However, if the X coordinate crosses the boundary of the display memory, the X coordinate is forcibly set to the initial value O by the X coordinate control unit. Drawing can be done in the area, and the display screen can be easily scrolled up.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram of a drawing address control section of the CRT controller of the apparatus of this embodiment, and FIG. 2 is a schematic diagram for explaining the display memory 1.

The overall configuration of this embodiment is as shown in FIG. Of the configuration shown in FIG. 3, the display memory 1 will first be explained based on FIG. 2.

In the figure, the display memory 1 has a storage area of M pixels and XN pixels, and in this embodiment, as shown in the figure, the drawing of KV tract T is performed from the necessary y coordinate=k at the drawing start address, as shown in the figure. The character F is drawn at a position across the boundary of the display memory 1.

The configuration of the CRT controller 3 for performing the above-described drawing will be explained with reference to FIG.

In the figure, numeral 10 denotes a drawing processor, which inputs drawing commands and determines the coordinates of each drawing point. Reference numeral 11 denotes an X address generation unit, which outputs the X coordinate (x=O−M−1>) based on the output of the drawing processor 10. Reference numeral 12 denotes an X address generation unit, which outputs the X coordinate (x=O−M−1>) based on the output of the drawing processor 10. It outputs the X coordinate which is incremented by 1 from the drawing start address based on the drawing start address.In addition, this y at 92 generating section 12 outputs the X coordinate when the drawing start address is from O, y=0.1, 2. ..., N-1 will be output, but if the drawing start address is other than the initial value O, it will exceed V=N-1 and output the X coordinate. 13 is an address conversion unit, which generates both of the above addresses. Part 11.12 x
, X coordinates are input, converted to a physical address of L=X+MV, and outputted to the display memory 1.

Reference numeral 20 denotes an X-coordinate control section, which detects that the X-coordinate has reached N-1 and outputs information for setting the detected X-coordinate to the initial value O to the drawing processor 10. This X coordinate control section 20 includes a shift register 21.
It is composed of AND circuits 22 and 23, an OR circuit 25, and a set register 24. The shift register 21 shifts the contents of the register one by one using the output of the y address generator 12 as a clock, and the output terminals of the most significant bit and the second most significant bit are connected to the AND circuits 22 and 23. Connected to one input terminal. The set register 21 also stores the maximum value of the X coordinate (N-1>+
In this embodiment, the most significant bit and the output terminal of the second most significant bit of the set register 24 are connected to the other input terminal of the AND circuit 22 and 23. It should be noted that display memory 1. allows two types of coordinates to be set in this way. If the image size of display 2 is 21I, for example, 128X12B, 256X
The above-mentioned display screen can be scrolled up in accordance with each of the two sizes of H.256. For this reason, an OR circuit 25 is provided which inputs the outputs of the AND circuits 22 and 23, and when the output of the OR circuit 25 is old GH, the address converter 13 is set to Wa, and the An interrupt signal that sets the X coordinate to the initial value O is output to the drawing processor J10. In this embodiment, only the upper two bits of the set register 24 are set to "1", so When "1" is set in the upper two bits of the shift register 21, the old gh is output from the OR circuit 25. The second most significant bit is the y-coordinate N of the display memory 1 (the X-coordinate of the display memory 1 is actually N
Since there is only -1, this X coordinate corresponds to an imaginary coordinate beyond the boundary line of the display memory 1). Incidentally, in this embodiment, the y coordinate N is detected as a result, but this means that the y coordinate N-1, which is the boundary line of the display memory 1, is detected.
This is equivalent to detecting .

The operation of the device configured as above will be explained.

When a drawing command is input to the drawing processor 10, the drawing processor 10 calculates the coordinates of a drawing point based on the command, and generates logical coordinates x(0 to M-1) from the x and y address generation units 11.12, respectively. , generates the logical coordinate y.

Here, the drawing to the display memory 1 is performed as shown in FIG.
Draw character T from coordinate k (drawing start address),
Assuming that the character F is drawn in two areas that straddle the boundary of the display memory 1, the y-coordinate generator section 12 first outputs the coordinate k, and while this coordinate k is being output, the x-coordinate address is From the generation unit 11, the X coordinate is O~127
is output. After this, every time the X coordinate reaches 127,
The coordinates are accumulated by 1 and output as +'l and k+2. The output coordinates of both address generators 11 and 12 are input to the address converter 13, where L=x0M−
It is converted to the physical address of y.

That is, the output of this address converter 13 is 128, 128, +1.128, +2. ...+12 to 128
7.128 (k+1>, 128 (k+1>+1) are output as consecutive numbers of addresses, and the drawing position in the display memory 1 is specified by this physical address.

Here, when the X coordinate reaches N-1 and the drawing of the character T is completed, the X coordinate becomes N, but at this time, 1'' is set in the upper two bits of the shift register 21, and the AND circuit 22
．． The OR circuit 25 is established and the old Oh is output from the OR circuit 25.

Then, a wait is applied to the address conversion unit 13 to temporarily stop the address conversion, and the drawing processor 10
An interrupt signal to set the X coordinate to the initial value O is output. For this reason, (1^ image processor FJ10G, 1y
The address generator 12 is controlled to generate a y-coordinate O in place of the y-coordinate N. Therefore, the address conversion section 13
, the physical addresses 0.1.2 .corresponding to the address of the first line of display memory 1. . . 126 and 127 are output, making it possible to draw in two areas that straddle the boundary line of the display memory 1. After this, addressing is continued until the y-coordinate becomes -1, thereby completing the drawing of one frame on the display 2.

Once such drawing is completed, the next time the contents of the display memory 1 are read out, the readout start address is changed from a to b as shown in Fig. 4, thereby making it possible to scroll up the display screen as described above. It becomes possible.

As described above, in this embodiment, when the y-coordinate exceeds the boundary line of the display memory 1, the next y-coordinate is forcibly initialized (11
[Since the value is reset to 0, drawing can be performed in two areas that straddle the boundary of the display memory 1, and the display screen can be easily scrolled up.

Note that the present invention is not limited to the above embodiments, and various modifications can be made within the scope of the gist of the present invention.

[Effects of the Invention] As detailed above, according to the present invention, when the ya mark crosses the boundary line of the display memory, the y coordinate is forcibly returned to the initial value O. Drawing can be done in the area, and the display screen can be easily scrolled up.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a drawing address control section of the display controller of the present invention, FIG. 2 is a schematic explanatory diagram showing an example of a display memory, FIG. 3 is a block diagram showing the configuration of a display device, and FIG. 4 FIG. 2 is a schematic explanatory diagram illustrating drawing to a display memory and its display screen. 1...Display memory, 2...Display, 3...
Display controller, 10... Drawing processor, 11.
...

Claims (1)

[Claims] M(x=0~M-1)×N(
In a display device that controls drawing to and reading from a display memory (y = 0 to N-1) and displays the contents of the display memory on a display, the display controller inputs a drawing command to control drawing for each drawing point. a drawing processor that determines the coordinates of the drawing processor; an x-address generation unit that outputs the x-coordinate (x=0 to M-1) based on the output of the drawing processor;
A y-address generation unit outputs a y-coordinate incremented by 1 from the drawing start address based on the output of the drawing processor, and L=x+M・based on the outputs of both address generation units.
an address conversion unit that converts the physical address of y into a physical address and outputs it to the display memory; and an address conversion unit that detects that the y coordinate has reached N-1 and sets the y coordinate to an initial value of 0 after this detection. 1. A display device comprising: a y-coordinate control section that outputs an output to a processor.