JPS597115B2 - How to create an address - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to raster scan CRT (cathode ray tube) displays, and more particularly to an improved method for accessing a character generator (memory).

An object of the present invention is to realize a display device that can be used not only as a normal character display device but also as a kanji display and a simple image display.

FIG. 1 shows an example of the configuration of a conventional CRT display.

A conventional access method will be explained with reference to this figure. Reference numeral 1 denotes a refresh memory for storing information to be displayed on the CRT display screen for a predetermined period of time.

In the raster scan method, by performing the read operation of the refresh memory several tens of times per second, the
Text information etc. are displayed on the RT display screen. 2 is a character selection code, which is composed of a 6-bit code corresponding to the storage capacity of the character generator 3.

CS is used to select a character generator when a plurality of character generators are used. The No. 3 character generator can accommodate 64 display characters, usually consisting of 5 x 7 or 7 x 9 dots.

In this example, one character is represented by 5×7 dots as shown in FIG.

4 is a line selection circuit, and 5 is its output line selection signal, which is used to select lines o, 1, . . . of the character pattern in FIG.
. . . This is a signal for selecting 7.

Characters can be displayed using the character selection code 2 and line selection signal 5.

Now, if the character selection code 2 indicates the character "A" and the line selection signal 5 indicates the line "01", the output 6 of the character generator 3 will be 00100, and this output 6 will be sent to the parallel-serial conversion circuit 7, video circuit 8
Dodoi'' is displayed through (Figure 2).

Next, even when the character selection code changes to the second character ゜゜B'', the line selection signal does not change (because of the raster scan method), and the output of the character generator 3 becomes 11110.

In this case, dot ゛口'', ゜゛ha'', ゛゛ho'' are C
Appears on the RT display screen. Similarly, line ゛゛1''
The display will move from left to right and when all is completed,
Next, the process moves to line "2" and the same operation is continued. A timing circuit 9 adjusts the timing of the above operation.

10 is a scanning circuit, and 11 is a CRT.

Conventional character displays have been described above, but character displays and kanji displays were conventionally considered to be different things.

The present invention aims to break through these barriers and display not only alphanumeric characters but also Chinese characters on the same display device. That is, the present invention expresses alphanumeric characters with one word, allocates four words to kanji, and adds selection bits (additional information) such as alphanumeric characters and kanji, images and characters, 16 raster display and 32 raster display, etc. This provides a display device that can be used not only as a normal character display device, but also as a kanji display and a simple image display. That is, a method is provided for accessing a character generator by combining a character selection code, a line selection code, and the additional information. This will be explained in detail below using the drawings.

FIG. 3 is a diagram for explaining to which part of the display device the present invention applies.

In FIG. 3, a microprocessor 21 controls reading of display information from the refresh memory 22. In FIG. 23 is a microprocessor bus, and 24 is an address line for transferring character selection codes and the like.

A display controller (CRTC) 25 generates a line selection signal 26 and the like.

27 is a character selection code, and 28 is additional information for selecting whether to use alphanumeric characters, kanji, or images.

Reference numeral 29 denotes a buffer for synchronizing the timing of the control information with CRT scanning.

30 is the data line C read out from the refresh memory.
The dot pattern information to be displayed on the RT screen is transferred to the character generator 31.

Character generator 31 is composed of RAM.

32 is a serial/parallel converter circuit, and 33 is a CRT (cathode ray tube) display.

A new access method for normal character display operation and kanji display operation using the CRT display device as described above will be explained.

FIG. 4 is an enlarged view of the portions in FIG. 3 that are directly related to the present invention.

In FIG. 4, numeral 41 is a line address register, which requires 5 bits if there are 32 rasters per line at maximum.

Reference numeral 42 denotes a character selection code register, which has an 8-bit configuration for selecting 256 character types.

43 is a register for additional information, which displays an under cursor,
Consists of 2 bits for reverse display and normal numeric display.

44 is 1 bit for accessing kanji, 45 is 16
It consists of 1 bit that determines whether to use raster display or 32 raster display.

A total of 16 bits can specify 64 kilowords of alphanumeric characters, kanji, etc. in the character generator.

Other numbers are the same as in FIG. The number of bits required to represent one character will now be explained.

As shown in FIG. 5, alphanumeric characters such as alpha bets can be displayed clearly with 10 bits horizontally and 16 bits vertically, so this is taken as one word area. On the other hand, since kanji characters require 20 bits horizontally and 32 bits vertically, they require an area of 4 words. A method for accessing characters that occupy different areas of the character generator will be described below. (1) In the case of displaying kanji characters In this case, 32 rasters are required, so all 5 bits of the line selection signal 26 are required.

It goes without saying that this line selection signal 26 is a signal for addressing characters in the character generator 31, and is also used as a line scanning signal. Next, all 8 bits of the character selection code 27 can be used to specify Kanji characters.
The numeric designation bit 46 is fixed at ``0'' in this case.
Kanji designation bit 47 is fixed at 1. The raster number designation bit 48 is fixed to the 32 raster side. In total, 13 bits can be used to specify kanji, and 8
You can specify kilowords of kanji. (2) In the case of alphanumeric display In the case of alphanumeric display, 16 rasters are enough to display characters clearly.

Therefore, if the characters are displayed using the 32 rasters required for displaying kanji characters, the characters will be displayed with larger characters than necessary. Also, if the character generator is simply displayed in 16 rasters, only half of the memory of the character generator is used and is wasted. Accordingly, in the present invention, when access is made using a combination of the raster number designation bit 48 and the line selection signal 26, the memory area of the character generator 31 is used without wastage, as shown in FIG.

Specifically, the object of the present invention is achieved by using the raster number designating bit instead of the most significant bit of the five bits of the line selection signal 26.

In this case, by setting the raster number designating bits to 0 for each character, the line selection signal 26 becomes 4 bits, and 16 rasters can be displayed.

When displaying kanji, the kanji designation bit is fixed at 47 and 1.
The most significant bit of line selection signal 26 is selected. In case of alphanumeric display, kanji designation bit 47 is fixed to ``O''.
Raster number designation bit 48 is selected. Since the raster number designation bit 47 is set to ``1'' or ``O'' for each character under the control of the display controller 25, the entire character generator memory can be used. character generator 31
The size relationship of alphanumeric characters and kanji characters accommodated in is as shown in Figure 5. Depending on this size relationship, 32 raster display,
By switching between 16 raster displays, it is possible to display kanji and alphanumeric characters in an optimal size. In the present invention, one bit of the line selection signal is replaced by a raster number designation bit, but it is clear that a configuration in which two or more bits of the line selection signal are replaced is possible.

Furthermore, a simple image display such as a graphic display can be easily performed by selecting display block units equal to those for Chinese characters (for example, 10×32 bits).

The present invention has created a display that has functions such as a kanji display and a simple image display in addition to the conventional character display, and its economic effects are extremely large.

This means that what used to require three machines is now just one. Furthermore, since the configuration of the present invention uses a RAM for the character generator 31, display information can be rewritten by changing the contents of the refresh memory 22, and predetermined characters can be instantly rewritten with the same access as described above. There are advantages.

As explained in detail above, the present invention uses a combination of line selection bits and raster number specification bits to increase the number of rasters per character.
It is possible to perform 6 raster display and 32 raster display, and as a result, alphanumeric display, kanji display, and simple image display can be performed on the same display device.

[Brief explanation of the drawing]

FIG. 1 is a diagram for explaining a conventional display method, and FIG. 2 is a diagram showing an example of a dot pattern of a refresh memory.
FIG. 3 is a diagram showing one configuration example of the display device of the present invention, FIG. 4 is a partially enlarged view of FIG. 3 showing the bit arrangement for address selection of the character generator, and FIG. FIG. 2 is a diagram showing the size relationship of alphanumeric characters and kanji characters stored in a character generator used for.

Claims (1)

[Claims] 1 A new feature that combines a character selection bit used only for character selection in a character display, a line selection bit used for scanning character dot patterns, and multiple additional bits for special display. At the same time, depending on the state of the additional bit, a plurality of upper bits of the line selection bit are fixed to the state of the additional bit, and the remaining lower bits, the character selection bit, and the An address creation method characterized by creating an address in combination with additional bits.