JPS608891A - Character generator control system - 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, and particularly to a control method suitable for a character generator.

[Background of the invention]

A conventional example will be explained using FIGS. 1 and 2.

FIG. 1 is a block diagram of a conventional example, and FIG. 2 shows an example of one display pattern. Display on a CRT unit is performed in the following procedure.

Character code 4 read from refresh memory 3 and rask address 5 to C output from display control device 1
G address 7 is output, character generator 8 is accessed, and character pattern 9 is output. Character pattern 9
is converted into serial data by shift register 10 and sent to CRT.
Displayed in unit 11.

The method of reading the character generator 8 through the data bus 12 is that the character code register 13 and the rask address register 14 set through the data bus 12 become the CG address 7, and the character generator 8 is accessed to read the character pattern 9 to the CG register. In addition to the CRT unit 11, a dot printer or the like that needs to output the dot patterns shown in FIG. 2 in the order of COL, I, 2.5, etc. In a system in which the characters are connected and share the character generator 8, it is necessary to read out all the patterns shown in FIG. 2 from the character generator 8, and in a display device such as a microprogram type, the processing time for reading becomes a problem.

Furthermore, when reading out the character generator 8 via the data bus 12, if it overlaps with the display period to the CRT unit 11 via the refresh memo 'J5, the CRT unit 11
There was a drawback that one refresh was interrupted and one screen flickered.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a control method for a character concentrator that does not degrade system performance or cause flickering on the screen of a CRT unit.

[Summary of the invention]

The present invention provides a memory for refreshing the display surface of a display device, a memory address, a display control device for generating a display timing signal indicating a raster address display period, a key code read from the memory, and a character code read from the memory. In a display device equipped with a character generator that generates a pattern, a raster address counter and a character code register are provided, so that character patterns for all raster addresses of the character specified by the character code register are generated during one display retrace period. It is characterized by being read from a character generator.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 2 and 6.

The display control device 1 has memory address 2. Rask address 50 display timing 15 is output.

Memory address 2 is connected to refresh memory 6 and outputs character code 4.

Character code 4. The raster address 5, the output of the character code register 15, and the output of the raster counter 22 are connected to the selector 6, and by the select signal 16,
One of them is selected and outputs the CG7 dress 7, which is connected to the character generator 8.

Character pattern 9 which is the output of character generator 8
is the CRT unit 11 via the shift register 10
and the CG buffer 26.

The output of the CG buffer 25 is connected to the data bus 12.

The character code 15 input is connected to the data bus.

The CG access control 21 receives a 1 display typing signal 15, a start instruction signal 19, a carry signal 18, and select signals 16. It is configured to output a count up signal 17 and an end signal 20.

C/? The procedure for displaying on the T unit 11 is the same as in the conventional example described above when there is no access from the data bus, and the procedure for displaying on the character generator 8 through the data bus 12 is
The operation of this embodiment for reading out will be explained below.

After the code of the character to be read is set in the character code 15 via the data bus by a microprocessor or the like, upon receiving the activation instruction signal 19, the CG access control 21 operates.

The display signal 15 is connected to the selector 6 directly or via the CG access control 21, and during one display period, that is, when the display timing signal 15 is generated, the character code 4. Raster address 5 is CG address 7
However, during the retrace period, when 'f, that is, the display timing signal 15 is off, the character code register 15.
The raster counter 22 becomes the CG address 7 through the selector 6.

When the CG access control 21 receives the activation signal 19, it detects the blanking period from the display timing signal 15, stores the character pattern 9 which is the output of the character generator 8 in the CG buffer 23, and outputs the count amplifier to the raster callan J'22. Signal 17 gives a count up instruction. The single character pattern 91' is stored in the CG buffer in the same manner. That is, they are stored in the CG bar 26 in the order of ROW1, 2, . . . , 9 in FIG. Raster counter 22
Carry signal 18. Alternatively, by detecting the value of the raster counter 22, storage in the CG buffer 25 is completed, and the completion signal 20 is reported.

A microprocessor or the like that receives the end signal 20 can read the entire CG pattern of the character specified by the character code register 15 from the CG buffer 23 through the data bus 12.

CG buffer 25'ls: It is also possible to directly store it in the main memory or the IJ friend memory 6 without using it.

〔Effect of the invention〕

According to the present invention, the entire dot pattern of a character code can be read during the retrace period of the CRT unit display, so that the CRT unit display busyness is not affected in an apparatus in which the character cornerator is used for a purpose other than the CRT unit display. Moreover, there is an effect that the performance of the device is not impaired.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a conventional example, FIG. 2 is a display pattern diagram, and FIG. 5 is a block diagram showing an embodiment of the present invention. 1...Display control device. 2...Memory address. 3...Refresh memory. 4...Character code. 5... Rusk address. 6...Selector. 7...CG address. 8...Character generator, 9...Character pattern. 10...Shift register. 11...CRT unit. 12...Data bus. 15...Character code register. 14...Rask address register. Closed 1st mouth 2nd mouth

Claims (1)

[Claims] 1. A memory and a memory address for refreshing the display surface of a display device, a display control device that generates a display timing signal indicating a display period of the task address 9, a character code read from the memory, and a character code read from the task address. By providing a raster address counter and a character code register in a display device equipped with a character generator that generates character patterns. A control method for a character generator, characterized in that character patterns for all rask addresses of a character designated by the character code register are polished and extracted from the character generator during a display retrace period.