JPS592028B2 - display terminal device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a program-controlled display terminal device, and uses direct memory access (hereinafter referred to as DMA) to facilitate multiple control operations by shortening processing time.
The present invention relates to a device for detecting characters stored in a memory circuit and repeatedly writing arbitrary characters to the memory circuit.

In general, display terminal devices have a configuration in which various input/output devices (printers, cassette magnetic tape devices, etc.) are connected and are connected to a computer via a modem, so changes in the configuration of input/output devices, A program control method is widely used in order to easily handle changes in control procedures with computers and changes in screen editing functions.

Generally, as an on-screen editing function of a display terminal device, the same character is repeatedly written into the memory circuit corresponding to the entire display screen or a portion thereof (for example, when clearing the entire screen with ``00'' or inserting a dividing line with an asterisk). Because the function of detecting specified characters that determine a specified area on the display screen is often used, the program control method, which is conventional sequential control, takes longer to process than the wire logic method, and the line from the input/output device calculation center etc. In a configuration in which these are connected, multiplex control becomes extremely inefficient.

An object of the present invention is to detect specified characters and repeatedly write characters by using direct memory access (DMA) to directly manipulate data in memory (not under program control), thereby increasing processing efficiency and achieving multiple control. An object of the present invention is to provide a display terminal device that improves efficiency.

Next, the present invention will be explained by giving a specific example.

FIG. 1 shows an example of the configuration of a display terminal device. A conventional program-controlled display terminal device has a display unit 1 for displaying characters, a character generation circuit 2, a display control circuit 3, and connections with external equipment such as a keyboard, modem, input/output device, etc. It is composed of an input/output control section 6 for controlling the entire circuit, a common control section 5 for controlling the entire circuit, and a storage circuit 4 for temporarily storing control programs and various data. This device usually performs the following processing.

(1) Display data on the screen and control the screen (described later) in accordance with input data from the keyboard. (2) Send screen display data to a line via a modem or transmit it to an output device. (According to the data sent from the line via the 3-way demodulator or the input data from the input device,
Writes data to the screen and performs corresponding screen control.
By the way, screen control of a display terminal device often involves writing the same character on the entire screen or a part of the screen and transferring data within the memory circuit 4, and the same process is repeated for the number of characters.In the case of program control, This requires a lot of processing time. In addition, in order to improve the operability of the device and increase the transfer efficiency of the entire system, we have created several areas on the screen, such as the area where data input from the keyboard is permitted, and the area where display data from the center is protected (for example, the area where data input from the keyboard is permitted). data), the data part sent to the center,
Recently, a method has been widely used in which the input section is divided into numbers, etc., but when this method is applied, the character of the relevant screen section must be determined according to the character of the relevant screen section when transferring data and performing screen control. It is necessary to check in advance each time, and the second
As shown in the figure, the [instruction characters] 21, 22, 23, and 24 that define the character of the screen must first be found.

Therefore, in this case as well, like the repeated writing process of the same character,
Reading from the memory circuit is repeated until the target character is detected, which requires a large amount of processing time and reduces the processing capacity of the entire device. Therefore, in the present invention, in order to reduce the time required for repeatedly writing a specific character and detecting a specified character, the "D" shown in FIG.
An MA control circuit was provided to execute these processes in a short time using DMA transfer processing rather than program control.

FIG. 3 shows an example of the configuration of this circuit. In FIG. 3, an address counter 31 specifies a read or write address in the memory circuit, and prior to starting processing, the start address of a range for repeated writing or detection of a specified character is set. The end address register 32 is a register that sets the final address of a range in which repeated writing or specified character detection is performed. The match circuit 33 detects a match between the contents of the address counter and the end address register, and is a circuit that notifies that the processing has reached the end address. The data register 34 is a register in which the code of a character to be repeatedly written or data read from the memory circuit is set. The code detection circuit 35 is a circuit that checks the contents of the data register when a designated character is detected, and detects that the corresponding code has been read out from the storage circuit.
The command register 36 is a register for storing a command code sent from the common control unit in order to specify what processing is to be performed on the DMA control circuit.

The status display register 37 is a register indicating under what termination conditions the process was terminated. The timer 38 is D
This is used to count the time when repeated character writing and specified character detection processing under MA control is executed in intervals of a certain period of time. Finally, the control section 3
9 is a part that comprehensively controls the entire circuit. The processing procedure will be explained below using the specified character detection operation as an example.

First, in order to designate the range of the storage circuit in which the designated character is to be detected, its start address and end address are set in the address counter and end address register, respectively. At this time, if it is desired to interrupt the process after a certain period of time, the time is set for the timer. Next, by setting a code that instructs the command register to start processing at the same time as the specified character that you want to detect, this circuit will send a command to the CPU in the common control section.
An MA start request is issued, and when the request is accepted, the storage circuit is addressed according to the contents of the address counter, and data read from the corresponding address is set in the data register. In this manner, DMA transfer is continued while incrementing the address counter until the corresponding code for the specified character is detected. If the corresponding code is detected, the control unit will
Set a code indicating this to the status display register, and
Turn off MA transfer request. Furthermore, even if the end address is reached or the timer reaches the set time before the corresponding code is detected, a code indicating this is set in the status display register at that time, and the DMA transfer request is also turned off. Finish the process. When the DMA transfer request is turned off, execution of the control program starts again, but at that time, by reading the contents of the address counter in the control program, you can know the address where the corresponding code was detected, and also read the contents of the data register. By reading it, you can know the data contents of that address. Also, when repeatedly writing a specific character, set the data to be written in the data register, the data write range in the address counter and end address register, respectively, and then set the code that commands repeated writing in the command register. conduct.

As described above, by using DMA transfer for the process of detecting a specified character and repeatedly writing a specific character, the process that was conventionally performed by a combination of several instructions can be reduced to a single read from the memory circuit. This can be realized by , or writing, and the effect is particularly great when the reading detection and writing processes are repeated for several thousand characters, such as in a CRT display terminal device.

[Brief explanation of the drawing]

FIG. 1 shows an example of the configuration of a display terminal device, and FIG. 2 shows an example of a screen when the screen is divided into several areas. FIG. 3 shows a circuit configuration of a DMA control circuit which is an embodiment of the present invention. 1...Display section, 2...
Character generation circuit, 3...Display control circuit, 4...
...Memory circuit, 5...Common control section, 6...
...input/output control unit, 7...DMA control circuit,
21-24...Specified characters, 25-28...
...Parts whose characteristics are defined by designated characters 1, 2, 3, and 4, respectively, 31...Address counter, 32...
... End address register, 33 ... Match circuit, 34 ... Data register, 35 ...
...Code detection circuit, 36...Command register, 37...Status display register, 38...
...Timer, 39...Control unit.

Claims (1)

[Claims] 1 Direct memory access (DMA) is used when controlling a display terminal device with a program, when detecting a specified character from among the characters stored in the memory circuit, and when repeatedly writing arbitrary characters to the memory circuit. A display terminal device characterized in that processing is performed using.