JPS6140998B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a raster scan type character display device equipped with a refresh memory, and in particular, as a so-called typewriter, it is equipped with a high-performance document function for quick recovery from misinputs and flexibility in editing. The present invention relates to a character display device used in systems such as word processors.

When performing document processing such as editing using a character display device, it is desirable that various format information such as scales indicating character positions, tabs, left and right critical points, etc. be displayed on the screen simultaneously with the characters. In addition, the type and display form of this format information can be changed arbitrarily and flexibly as needed.
It has to be a choice.

Accordingly, an object of the present invention is to provide a character display device suitable for use in document editing work and the like. Another object of the present invention is to provide a character display device that allows the display mode of format information to be freely changed while simplifying the refresh memory and its peripheral circuits.

In order to achieve the above object, in the present invention, a random access memory is used as a refresh memory, and character data and format data are stored in this memory by correlating addresses with each other to form a screen. Format data is read from the memory during the horizontal scanning period for format display among the horizontal scanning lines, character data is read from the memory during the horizontal scanning line period for character display, and characters and format information are displayed on the screen. Configure so that they are associated and displayed at the same time. The format information can be changed independently of the character data by rewriting the format data stored in the format area of the refresh memory. Furthermore, the positional relationship between format data and character data on the screen is uniquely determined by the correspondence between the storage addresses of both data in the refresh memory, and the method of reading the refresh memory is by changing the format data. It can be constant regardless of the

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a character display device according to the present invention will be described in detail below with reference to the accompanying drawings.

FIG.
1 is a block diagram showing a line character display device; FIG. Note that the numbers in parentheses in the figure indicate the number of signal lines.

The configuration and operation will be explained below with reference to FIGS. 2 to 4.

Display data (character data and format data) is taken in from a CPU (Central Processing Unit) via a buffer 1 to a random access memory (referred to as RAM) 2 as a refresh memory. At this time, the CPU supplies an R/W signal specifying writing or reading and a CPU-side system clock. When writing display data to RAM 2, the R/W signal enables buffer 1, write timing gate 3, and 256-base counter 4. Counter 4 counts the CPU clock,
Its output (8 bits) is supplied to RAM 2 via write timing gate 3 and OR gate 5 as a write address code. In this embodiment, RAM2 is 2048 bits (256 words x 8 bits),
Addresses 0 to 127 are assigned to store format data, and addresses 128 to 255 are assigned to store character data (see Figure 2).

The format data sent from the CPU is taken in via buffer 1 in synchronization with the CPU clock, and is written to 0 in RAM 2 indicated by the write address code supplied from counter 4.
They are written in order from address 127. Then
Character data sent from the CPU is sequentially written from address 128 to address 255 in RAM 2 in the same manner as above.

To display the display data stored in RAM2,
This is done in synchronization with the basic clock output from the generator 6. Counter 7 operates as a hexadecimal counter in cooperation with decoder 8, which outputs bit pulses _t1 to _t5 and digit pulse _t6 from the basic clock (see FIG. 4). In this embodiment, one character is displayed with five horizontal dots, and a space of one dot is provided between characters, and each bit pulse t ₁ to t ₅ is 1 dot.
The digit pulse t6 corresponds to each dot forming a character, and the digit pulse _t6 corresponds to a space between each character.

Digit pulse _t6 output from decoder 8
consists of a counter 9 and a decoder 10 129
Serves as the clock for the advance counter. Decoder 10 is 1
It outputs a trigger pulse T129 for each horizontal scan, and this trigger pulse T129 causes the CRT to
The horizontal scanning circuit 12 which supplies horizontal deflection current to (Cathode Ray Tuke) 11 is triggered.

The 128-decimal counter 13 counts the output of the 129-decimal counter 9 and outputs the lower 7 bits A1 to A7 of the read address code of the RAM 2 (see FIG. 3). Further, the hexadecimal counter 14 counts the trigger pulse T129 output from the decoder 10. That is, the contents of the hexadecimal counter 14 indicate horizontal scanning line numbers (L2 to L12 in FIG. 4). A vertical scanning circuit 15 that supplies a vertical deflection current to the CRT 11 is triggered by the output of the hexadecimal counter 14 at the end of the final horizontal scanning line L12. The hexadecimal counter 14 also supplies the most significant bit A8 (see FIG. 3) of the read address code of the RAM 2. In this embodiment, the horizontal scanning line L2~
Format data is displayed during the period L4, and character data is displayed during the period L6 to L12 of horizontal scanning lines. Therefore, the most significant bit A8 of the read address code is the horizontal scanning line L.
“0” for 2 to L4, horizontal scanning lines L6 to L
For 12, it becomes "1". Therefore, the read address codes A1 to A8 output from the 128-decimal counter 13 and the 12-decimal counter 14 are sent to the RAM 2 through the display timing gate 16 and the OR gate 5.
is supplied to Note that at this time, the read timing gate 16 is in an enabled state by the output of the inverter 17.

Thus, during each scanning period of horizontal scanning lines L2 to L4, the 8-bit parallel format data stored at addresses 0 to 127 in RAM 2 is sequentially read out. Formats Generator (FG)
18 receives the read format data and the scanning line number designation signal from the scanning line decoder 19, and outputs a format pattern signal (5 bits per word of format data) corresponding to each horizontal scanning line L2 to L4. bit). This format pattern signal is sent to a parallel-to-serial converter 21 via an OR gate 20. The parallel-to-serial converter 21 strobes the 5-bit parallel format pattern signal with bit pulses _t1 to _t5 , converts it into a serial format dot pulse train (see FIG. 4), and supplies it to the Z-axis amplifier 22. .

Similarly, during each scanning period of horizontal scanning lines L6 to L12, 8-bit parallel character data stored at addresses 128 to 255 in RAM 2 is sequentially read out. The character generator (CG) 23 is
In response to the read character data and the scanning line number designation signal from the scanning line decoder 24, each horizontal scanning line L6
A character pattern signal (5 bits for one word of character data) corresponding to ~L12 is generated. This character pattern signal is converted by a parallel-to-serial converter 21 into a character dot pulse train (see FIG. 4) synchronized with bit pulses t ₁ to _{t 5} and supplied to a Z-axis amplifier 22 .

In this way, character data and format data are processed as shown schematically in FIG.
It is displayed on the CRT 11 as a dot matrix of 5 dots horizontally and 3 dots vertically (for format data) or 7 dots vertically (for character data).

The character display device of the present invention is as described in detail above, and is capable of displaying format data and character data at the same time.Moreover, since a random access memory is used as a refresh memory, it is possible to display format data and character data simultaneously. Since the format data and character data can be changed and rewritten separately, and the format data and character data are stored in addresses that are associated with each other, the display positions of characters and format information are uniquely associated. , it has the advantage of simplifying the configuration of peripheral circuits of the refresh memory, etc., and is ideal for applications such as document editing processing.

Although the above embodiment is a one-line character display device, it goes without saying that a full-line character display device can be easily realized. Further, in the above embodiment, the number of words that can be displayed on the screen is the same for both characters and format information, but the number of words for both may be different. Even in this case, if the storage addresses of character data and format data are associated with each other, the peripheral circuit (readout circuit) of the refresh memory will not be complicated at all.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the character display device according to the present invention, FIG. 2 is a diagram explaining the storage area of character data and format data in the refresh memory, and FIG. 3 is a diagram showing the storage area of the refresh memory. Diagram showing the correspondence between addresses and address codes, 4th
The figure is a time chart for explaining the operation of the apparatus shown in FIG. 2... Refresh memory (random access memory), 3... Write timing gate, 4...
Write address generation counter, 11...CRT,
12...Horizontal scanning circuit, 13, 14...Read address generation counter, 15...Vertical scanning circuit, 1
6...Read timing gate, 18...Format generator, 19, 24...Scanning line decoder, 21...Parallel-to-direct converter, 23...Character generator.

Claims (1)

[Claims] 1. In a raster scan type character display device equipped with a refresh memory, the refresh memory is a random access memory, and character data and format data for one screen are stored in the memory with addresses associated with each other, Of the horizontal scanning lines that make up the screen, the format data is read from the memory during the horizontal scanning line period for format display, the data is read from the memory during the horizontal scanning line period for character display, and then displayed on the screen. A character display device characterized by displaying characters and format information at the same time by associating their positions.