JPS6041360B2 - Cursor display method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in the cursor display method of a character display device, and particularly to an attempt to enable accurate cursor display using a more simplified logic circuit.

An example of a character display device using a cathode ray tube (CRT), which is widely used as a display medium, will be explained with reference to FIG.

When display information is received from the pond system through the input/output interface 10, it is stored in the refresh memory 11. The address of the refresh memory 11 is specified by the contents of the cursor register (ram) 12 and cursor register (row) 13. On the CRT screen, an indicator, ie, a cursor, indicating where in the refresh memory 11 the next display information is stored is displayed. The new display information is displayed where the cursor is displayed. After storing the display information in the refresh memory 11, the cursor register (
The contents of column 12 are incremented to 11, and the cursor on the CRT screen is moved one character to the right in preparation for storing the next display information. The one-line memory 14 temporarily stores display information of the line being scanned by the electron beam of the refresh memory 11.

Each time the scanning of the electron beam moves to the next row, display information for the next row is transferred from the refresh memory 11 to the memory 14 by one row. The coded output of the memory 4 for one line is led to a character generation circuit 15 and converted into a character shape corresponding to the code. Where the CRT electron beam is scanning is determined by a column counter 16 that counts the horizontal position on the CRT screen, a row counter 17 that counts the vertical line position, and a line counter 18 that counts the line position within the line. This can be determined by the content of A synchronization signal is generated from a synchronization generation circuit 19 for decoding these three counters 16, 17, and 18, and the electron beam scanning of the CRT 21 is synchronized through a video synchronization synthesis circuit 20. The cursor display is based on two forces - Sol Regis E 12, 1
3 and the contents of the column counter 16 and row counter 17 match in the comparison circuits 22 and 23, in response to the output of the AND circuit 24. The cursor shape is created by a cursor shape generation circuit 25, logically ORed with the output of the character generation circuit 15 by an OR circuit 26, and converted into a serial signal by a parallel-to-serial conversion circuit 27. Thus, in this conventional example, cursor register (column) 1 is used to display the cursor.
2. Cursor register (low) 13, column comparison circuit 2
2. It can be seen that the low comparison circuit 23 is essential. The present invention has been made in view of the above circumstances, and aims to eliminate the need for the four types of circuits that were conventionally considered indispensable for displaying a cursor, and to display a cursor using a more simplified logic circuit. It is.

The details of the present invention will be explained below with reference to FIG.

In FIG. 2, the same parts as in FIG. 1 are given the same numbers and their explanations will be omitted. Now, with the development of IC technology, CPUs made with ratio 1 called microprocessors can now be obtained at low cost. FIG. 2 shows an example of a character display device to which this microprocessor is applied. In this example, the microprocessor 100 plays the central role of control, and therefore control information is stored in a control program storage section 101, which is usually constituted by a ROM. The content of the refresh memory 102 is characterized by being easily changed by the arithmetic and logical judgment functions of the microprocessor 100. The refresh memory 103 not only stores character codes, but also
As shown in the figure, one bit is added to determine whether or not to display the cursor at the position of that character. BI-B in the diagram
7 indicates a character identification bit (display data such as a character code), and the leftmost BO' cursor bit. It is clear that the addition of this cursor bit makes the two cursor registers in FIG. 1 unnecessary. 1 line memory 1
04 fetches one line of display information from the refresh memory 102 and temporarily stores it, but when the cursor bit output of the one line memory 104 is "1", a cursor pattern is output from the cursor shape generation circuit 25. , circuit 26,
A cursor of the CRT 21 is displayed via 27 and 20.

At this time, the contents of the memory 104 for one line have already been synchronized with the scanning of the CRT's electron beam, so
The column comparison circuit and row comparison circuit, which were essential in the figure, are no longer necessary. When storing new display information in the refresh memory 102, the refresh memory 102
All you have to do is search the cursor bit and store it at the address that is set to "1". Mike again. processor 100
If the cursor bit search takes a long time and becomes inconvenient, the address of the refresh memory 102 where the cursor bit is set to ``1'' may be stored in the data buffer 105, for example. In any case, independent hardware called a cursor register is unnecessary. If the access time and cycle time of the fresh memory 102 are far enough apart, one row of the memory 10
4 may not be necessary, but the same is true in this case because the contents of the refresh memory 102 are refreshed in synchronization with the CRT's electron beam. As is clear from the above, the present invention has the following advantages.

{1' A separate cursor register to store the force-sol position is no longer needed.

The comparison circuit that was necessary for leg force-sol display becomes unnecessary.

'3} The above resulting circuit can reduce the hardware cost by simplifying it.

Note that in FIG. 3, the cursor bit is one bit, but if multiple bits are used, cursors with various meanings or shapes can be used.

For example, one may be a cursor for operator input, and the other may be a cursor for another system, such as a host computer. Furthermore, even if the cursor bit is one bit, it is in principle quite easy to create a plurality of cursors. Further, in the above description, the CRT is used as an example of the display medium, but it goes without saying that the present invention is not limited to this and that plasma, liquid crystal, and other display devices can also be used.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a conventional character display device, FIG. 2 is a circuit diagram of a character display device to which the method of the present invention is applied, and FIG. 3 is a bit configuration diagram of a refresh memory. B0...Cursor bit, BI~B7...
Character identification bit, 25... Cursor shape generation circuit, 102... Refresh memory. Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1 The display information stored in the refresh memory is composed of display data such as character codes and cursor bits for displaying a cursor, and the cursor bits set to a specific value are read from the refresh memory. A cursor display method characterized by outputting and displaying a cursor pattern from a cursor shape generating circuit.