JPS61254986A - Character graphic 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 [Field of Application of the Invention] The present invention relates to a display device having both character display and graphic display functions.

[Background of the invention]

Generally, a character display device develops each character code into υ character pattern data using a character generator, and displays the data at a position defined by a row and a column. For continuous display, the data to be displayed is held in a display memory and read out from there repeatedly in synchronization with the scanning of the display. Recently, a type of device that retains developed character pattern data for two sides in a display memory has become common. By the way, on the display screen, appropriate spaces are provided between characters and lines. However, display memories provided in character display devices typically do not have storage locations corresponding to these spaces. Therefore, this type of display device is not capable of graphical display. In order to develop and display graphic data in a dot pattern, a display memory having memory locations corresponding to every pixel location on the screen is required. This type of graphic display device is described, for example, in Japanese Patent Laid-Open No. 57-30030.

Most conventional display devices having a character display function and a graph ink display function have a structure as shown in FIG. In the case of character display, character pattern data corresponding to the character code is taken out from the character memory 4 by the character generator 3 and set in the character display memory 5. In the case of graphic display, the graphic data is developed into a dot pattern by the graphic processing circuit 6 and set in the graphic display memory 7. image display memory 5,
The outputs read from 7 are combined in a superimposing circuit 8, and
given to CRT9. The communication control circuit 2 sends and receives data to and from the host computer via the communication line 1.

According to this structure, sufficient functions as a character/graphics display device can be realized, but a large amount of hardware is required by having a double character display memory and a graphic display memory.

From a practical point of view, there is a need for a character/graphics display device that is simple, compact, and inexpensive.

[Purpose of the invention]

An object of the present invention is to realize both character display and graphic display functions with a small amount of hardware. The object of the present invention is to provide a graphic display device.

[Summary of the invention]

The present invention eliminates the need to provide a graphic display memory separate from the character display memory, and intends to utilize the character display memory as a part of the graphic display memory. From a certain point of view, the present invention provides a character display device equipped with a character display memory that does not have a memory location corresponding to the character and line spaces, and a display memory that has a capacity corresponding to the character and line spaces. It corresponds to what was added. In character display mode, only the character display memory is conventionally used; in graphics display mode, both memories are concatenated to provide a contiguous address space capable of accommodating all pixel locations on the display screen.

Graphic coordinate data is converted by simple arithmetic processing into position data that is unique to the character display mechanism and consists of character positions (rows, columns) and dot positions within the character area.

[Embodiments of the invention]

On the display screen of a character display device, characters are arranged in rows and columns, as shown in FIG. The standard specifications for the screen of a kanji display device are 24 vertical lines x 40 horizontal columns (80 horizontal columns for alphanumeric characters). The case of a kanji display device will be explained below.

As shown in FIG. 4, the kanji pattern is formed within a 24 x 24 dot madrisk, but on the display screen, this 24 x 24 dot area 15 (herein referred to as the character pattern area) is There are spaces between characters and lines around it.

These spaces are allocated to each character, and the sum of the character pattern area and the space area is considered to form the character area. If the character spacing is 4 dots and the line spacing is 6 dots, add a 4 dot width area to the right of the 24 x 24 dot character pattern area 15 for the character spacing, and A character area 16 of 28 dots in width x 30 dots in height is defined by adding a 3-dot width area for line spacing. 24X2 on display memory
The 4-dot character pattern area 15 occupies 72 bytes,
The 28x30 dot character area 16 occupies 105 bytes. The display memory of a normal character display device only has 2 shift bytes per character and does not have storage locations corresponding to these space areas, so it is not suitable for graphic display, but it is not suitable for graphic display. By adding storage locations and preparing 105 bytes for each character,
Graphics can be displayed through any screen location, including space areas.

FIG. 1 shows one embodiment of the invention. In the figure, the same reference numerals as in FIG. 2 represent equivalent elements.

The main display memo IJ 10 has 72 bytes per character (24X
It has a capacity to accommodate character pattern data of 24 dots for one screen (24 lines x 40 columns). The reinforcement display memory 11 has a capacity corresponding to the sum of the inter-character and inter-line spaces. Therefore, the sum of the capacities of both memos + J10 and J11 is sufficient to accommodate the data of all pixel positions on the screen (1120 x 720 dots), in other words, 1 character per character.
05 bytes of character area pattern data for one screen can be accommodated. Both memories 10.11 may be separate memories or different areas of a single memory.

When modifying an existing character display device, another memory will often be added as the reinforcement display memory 11. However, in this case, it is necessary to make both memories consecutive in terms of addresses.

In character display mode operation, character memory 3, character generator 4 and main display memory 1O perform exactly the same processing as in conventional character display devices. In graphics display mode operation, main display memory 10 and supplementary display memory 11 are linked in terms of addresses to form one screen's worth of graphics display memory. At this time, both memories 10° and 11 are converted using an appropriate address translation mechanism.
A continuous address space corresponding to each 105-byte character area arranged in 24 rows x 40 columns is provided. The graphic data is developed into a dot pattern by the graphic development circuit 12, and at this time, the position of each dot is determined by the coordinate processing section 13! 6. The X and Y coordinates are converted into bit positions corresponding to character area positions and dot positions within the area indicated by rows and columns. This conversion is performed as follows.

FIG. 5 shows a state in which the display screen is oscillated in a character area of 28×30 dots. In the figure, the numbers written in each section (c character area) are the row and column numbers, and the numbers written in parentheses at the upper left corner of each section are the X and Y coordinates of the first dot of the character area. shows.

FIG. 6 shows the byte arrangement within each character area (28×30 dots), and the numbers enclosed in circles are byte numbers. However, ■, ■, ■, ...... (1 byte is
It is 4 pits long. As an example, assume that the coordinates of a given dot are )(=3%O, Y=500).

SOO÷30=16' ... Remainder: 2035
0÷28=12 ... Remainder: 14, that is,
This dot is the 14th dot on the 20th line in the character area corresponding to the 13th column on the 17th line. The first byte number of the 20th line in the character area is 4X19+1=@, and the 14th bit of this line corresponds to the 6th bit of the 2nd byte. Thus, this dot is in line 47, line 13.
It is calculated that this corresponds to the 6th bit of the @ byte in the display memory area that corresponds to the character area of the column.

The coupling circuit 14 supplies data read from the main display memory 10 to the CRT 9 in the character display mode, and collects data sequentially read from the main display memory 10 and the reinforcement display memory 11 in the graphic display mode. and supplies it to the CRT9.

Regarding the combination of the address spaces of the main display memory 10 and the supplementary display memory 11 for graphic display, it is simple to simply follow the former with the latter and sequentially accommodate character area data in units of 105 bytes. However, it is also possible to keep the address space of the main display memory 10 the same as in the character display mode (character pattern area) and to associate the address space of the reinforcement display memory 11 only with the space portion of each character area. be.

〔Effect of the invention〕

According to the present invention, by using a display memory for character display also as a graph ink display memory, a small and inexpensive character/graphic display device can be realized. Compared to a structure in which a character display memory and a graphic display memory are provided separately, the required memory capacity is reduced to about 60 inches. especially,
Assuming an existing character display device, display memory for the space area (less than 50 inches of conventional character display memory capacity)
By adding , you can easily add a graphic display function.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of an embodiment of the present invention, Fig. 2 is a block diagram of a conventional device, Fig. 3 is a character arrangement diagram of the display screen, Fig. 4 is a diagram of the character area on the display screen, and Fig. 5 is a block diagram of an embodiment of the present invention. is an arrangement diagram of the character area, and FIG. 6 is a diagram of the byte arrangement within the character area. 4...Character generator, 10...Main (first) display memory, 11...Reinforcement (second) display memory, 12...Graphic development circuit, 13...Coordinate processing unit, 14.・・・
Combined circuit.

Claims (1)

[Claims] 1. In a type of display device in which a character area consisting of a character pattern area and a surrounding space area is arranged in rows and columns to form a display screen, the display device has a capacity equivalent to the sum of the character pattern areas and is in character display mode. a first display memory section that holds all character pattern data for one display screen;
A second display memory section having a capacity corresponding to the sum of the space areas, and in the graphic display mode, graphic coordinate data is stored in the character area position in the connected address space of the first and second display memories and the dots in the character area. A character/graphics display device comprising: a coordinate processing unit that converts address data corresponding to a position.