JPH0235987B2 - - Google Patents

Description

[Detailed Description of the Invention] (a) Technical Field of the Invention The present invention relates to an output control method for a display device that displays display information such as characters, and particularly relates to a method for controlling the output of a display device that displays display information such as characters, and particularly when the display device is attached with another display device such as a printer. The present invention relates to an improvement in an output control method used when transferring display information of the display device to another output device in a system comprising the above-mentioned display device.

(b) Background of the Technology In general, a CRT display device as a display device displays display information such as characters on a cathode ray tube as a display section, but sometimes the display information displayed on the cathode ray tube is transferred to a recording paper. There arises a request to print on other documents. For this reason, the above
Systems have already been provided in which a CRT display device is equipped with a printer as another display device. In this type, the printing speed of the printer is
Since the display speed is much slower than that of a CRT display device, the control section of a CRT display device cannot be used as it is as a control section of a printer. For this reason, generally the printer side
A printer control section corresponding to the display control section of a CRT display device is separately provided, and in this type, the display control section includes, for example, a character generator that generates a character pattern as display information,
Since this character generator is equipped with a refresh memory that stores character codes for creating character patterns, and a CRT controller that controls the timing of outputting character patterns from the character generator, it is necessary to use the printer as described above. There is a problem in that the configuration of the control section becomes complicated, and the cost of the entire system increases accordingly. Therefore, in order to solve such problems, there is a growing demand for the display control section to serve as the majority of the printer control section.

(c) Prior art and its problems Conventional output control methods that meet the above-mentioned demands include, for example, controlling the vertical scanning signal of the horizontal scanning signal on the cathode ray tube during the period when the CRT display device is not displaying. Some printers operate the display control section as a printer control section during the retrace period. This means, for example, that the CRT controller above creates an interrupt signal that indicates the vertical retrace period, and then sends this interrupt signal to the microprocessor (hereafter
By interrupting the MPU), the above
Printer control information is output from the MPU, and based on this printer control information, the character generator outputs a character pattern, and the character pattern is transferred to the printer.

However, in such conventional output control methods, the output to the printer is controlled by software using the MPU, so the transfer speed of character patterns to the printer is relatively slow, and the printer's Depending on the model, the above transfer speed may be insufficient.

As a means to solve this situation, a counter circuit that sequentially outputs the printer control information is newly installed, and the outputs of this counter circuit and the refresh memory are input to the character generator via a multiplexer to generate characters. A hardware option that switches and transfers the character pattern from the generator to the cathode ray tube and printer is conceivable, but this type requires an additional counter circuit and multiplexer, so However, there is a problem in that the display control section itself becomes complicated and the cost of the entire system increases.

(d) Purpose of the Invention This invention has been made from the above viewpoint, and its purpose is to add a display device to another output device without unnecessarily increasing the cost of the entire system. An object of the present invention is to provide an output control method for a display device that can reliably transfer display information.

(e) Structure of the Invention The basic structure of the present invention is that display control means such as a commonly used CRT controller synchronizes an address signal corresponding to the number of display information on the display section with a horizontal scanning signal of the display section. This technology focuses on the fact that it has the characteristic of outputting an address signal that is continuous with the address signal of each horizontal scanning period during each horizontal retrace period, and outputs the address signal in the same period as the address signal of each horizontal scanning period. When transferring the display information to the output device, display control information for causing the display information generating means to output the display information to be transferred to the output device is stored in advance in the memory, and the display information is stored in the memory in advance during the horizontal retrace period immediately before the vertical retrace period of the display device. During the horizontal retrace period immediately before the vertical retrace period of the display device, an address signal not used by the display control means outputted from the display control means during the display is made to correspond to the display control information.
The output of the address signal causes the display control information to be output, and the display control information causes the display information generating means to output display information, and after the display information is temporarily stored in the buffer memory, the above-mentioned other information is generated during the vertical retrace period. This is to transfer the data to the output device.

(f) Embodiments of the invention Hereinafter, the present invention will be described in detail based on embodiments shown in the accompanying drawings.

FIG. 1 is a block diagram showing the overall system of a CRT display device for implementing the output control method according to the present invention.

In the figure, 1 is a cathode ray tube that serves as the display part of the CRT display device, 2 is an MPU that controls the entire system of the CRT display device, and 3 is the above-mentioned
A program memory 4 stores the execution program of the MPU 2, and 4 is a display control unit of a CRT display device. A refresh memory 6 is connected to the system bus to enable rewriting character codes as display control information to addresses corresponding to the address signals, and a read-only memory outputs character patterns as display information based on the character codes. (hereinafter referred to as ROM), etc., a parallel-to-serial converter 8 for converting a character pattern of a string of parallel dots outputted from the character generator 7 into a character pattern of a string of serial dots, and a parallel-to-serial converter The video control circuit 9 matches the character pattern output from the cathode ray tube 1 with the horizontal scanning speed of the cathode ray tube 1, and outputs the character pattern during the horizontal scanning period onto the cathode ray tube 1.

In this embodiment, the CRT controller 5 includes a cathode ray tube 1, for example, as shown in FIG.
When the number of characters displayed above is 640 characters (number of horizontally displayed characters 40/line x 16 lines), the number of displayed characters in other words is the address signal corresponding to the display address 0 to 639 on the cathode ray tube 1, that is, the address signal 0 to address 639. is output in synchronization with a horizontal scanning signal (raster scanning signal) in which the number of rasters per line of the cathode ray tube 1 is, for example, 12. Furthermore, the CRT controller 5 is
During each horizontal retrace period (THF) of the horizontal scanning signal, the horizontal scanning period during which horizontal scanning is actually performed, in other words, the address signal that is continuous with the address signal of the horizontal display period (TH) in which horizontal display characters are displayed. It is configured to output, for example, 24 times in the same cycle. Therefore, address signals from address 0 to address 63 are output to the first character display line of the cathode ray tube 1, and address signals from address 40 to address 103 are output to the next character display line. Similarly, address signals from address 600 to address 663 are output for the final character display line. In the vertical retrace period (tvf) of the horizontal scanning signal, the CRT controller 5 uses address 640.
continues to be output. In FIG. 2, the vertical display period (tv) indicates a period during which vertically displayed characters are displayed.

Further, in this embodiment, 10 is a printer;
11 is a printer control unit, specifically,
It consists of a parallel-serial converter 12 connected to the MPU 2 by a system bus, and a printer control circuit 13 that matches the output from the parallel-serial converter 12 to the printing speed of the printer 10 and sets the printing area. Reference numeral 14 is a buffer memory provided between the output end of the character generator 7 and the system bus of the MPU 2.

Next, the operation of the CRT display device according to this embodiment will be explained.

Now, as shown in FIG. 3, in addresses 0 to 639 of the refresh memory 6, character codes C0 to 639 corresponding to the display character A at each display address on the cathode ray tube 1 are stored in advance. Refresh memory 6 address 640
Addresses 663 to 663 contain character codes C640 to 663 corresponding to display character B to be transferred to the printer 10.
Assume that C663 is stored in advance.

In this state, the above CRT controller 5
As shown in FIG. 2, the address signals from address 0 to address 663 are output from the first display character line to the last display character line, with some overlap, but the display control unit 4 Since it is activated only during the horizontal scanning period (th),
Addresses 0 to 639 are sequentially given to the refresh memory 6 from the CRT controller 5.
Predetermined character codes C0 to C639 are read from the corresponding addresses of the refresh memory 6 and given to the character generator 7, and character patterns based on the predetermined character codes are sequentially read out from the character generator 7. Each character pattern is then displayed on the cathode ray tube 1 via a parallel-to-serial converter 8 and a video control circuit 9.

Furthermore, since the address signals from address 640 to address 663 outputted from the CRT controller 5 are those for the horizontal retrace period (THF) of the final display character line, they are generally not used by the display control unit 4. However, in this embodiment, the above address signal can be used. That is, when the MPU 2 activates the display control unit 4 during the horizontal retrace period (THF) of the last displayed character line, the character codes stored at addresses 640 to 663 of the refresh memory 6 are
C640 to C663 are read out and provided to the character generator 7. Then, the above character code C640
Character patterns based on C663 are character generator 7
, and each character pattern is stored in the buffer memory 14. At this stage, the horizontal scanning signal enters the horizontal retrace period (THF), so the operation of reading out the character pattern from the character generator 7 in the display control section 4 is completed. Then, the MPU
2 recognizes the above by the interrupt signal from the CRT controller 5, and the MPU 2
reads the character pattern stored in the buffer memory 14 and transfers it to the printer control section 11. As a result, the characters displayed on the CRT display device are
It is reliably transferred to the printer 10.

In the above embodiment, a printer is used as the other output device, but the output device is not necessarily limited to this, and a hard copy device or the like may also be used.

(g) Effects of the Invention As explained above, according to the output control method for a display device according to the present invention, when transferring display information of a display device to another display device, the existing display control means can control the output of the display device. By using the address signal that is not used as the address signal for display information on the existing display control section and simply adding a buffer memory to the existing display control section, it can be shared as a display section for other output devices, so the system as a whole can be improved. Display information on a display device can be reliably transferred to another output device without unnecessarily increasing costs.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the overall system of a display device for implementing the display device output control method according to the present invention, FIG. 2 is a schematic diagram showing the characteristics of the display control means used in the present invention, and FIG. The figure is an explanatory diagram showing an example of the contents stored in the refresh memory. 1... Braun tube (display section), 5... CRT controller (display control means), 6... Refresh memory, 7... Character generator (display information generation means),
8...Parallel-serial converter, 9...Video control circuit,
10...Printer (output device), 11...Printer control unit, 14...Buffer memory.

Claims (1)

[Claims] 1. When transferring the display information of a display device to another output device, display control information for causing the display information generating means to output the display information to be transferred to this output device is stored in advance in a memory, and the vertical An address signal not used by the display control means output from the display control means during the horizontal retrace period immediately before the retrace period is made to correspond to the display control information,
During the horizontal retrace period immediately before the vertical retrace period of the display device, the display control information is output by outputting the address signal, and display information is output from the display information generating means by the display control information, and the display An output control method for a display device, characterized in that information is once stored in a buffer memory and then transferred to the other output device during the vertical retrace period.