JPS5829513B2 - Special character selection control method - Google Patents

Description

Detailed Description of the Invention The present invention relates to a dot printer that prints characters in a dot matrix or a display that displays them, and provides a special character selection control method that allows special characters other than commonly used characters to be printed or displayed with a simple configuration. Regarding.

The following explanation will be limited to dot printers.

1 as a character generator for the commonly used standard 128 characters.
At the stage of manufacturing character generator chips, a mask ROM was used to write character codes.

In addition to the standard 128 characters, for example, “Usu January 1 year, Birth”.

When you want to additionally print a small number of special characters such as "Yen".

These codes were written into a mask ROM as a character generator for the special characters.

For this reason, when special characters are required, the code in the mask ROM must be changed each time, resulting in a problem of high mask (mold) costs.

In view of the above points, the present invention provides FIELD PROGR-A
MMABLE READ 0NRY MEMORY (hereinafter abbreviated as P,ROM) is added, special characters are stored and stored in the P,ROM, and the mask ROM and P,ROM
It is designed to be used selectively.

A special character selection bit is written in the code read out first of each character in the PROM, and when the special character selection bit is read out, the PROM is used to print. be.

Table 1 is the standard 128 character code table based on the JIS code, and Table 2 is the katakana lowercase letter "yo" among the characters in Table 1.
The matrix pattern code table of 01902・
....03 are read out sequentially.

The matrix pattern code of the characters in Table 1 is written into the mask ROM.

Table 3 is a special character code table based on JIS code,
Table 4 shows a matrix pattern code table for "Tate" among the characters in Table 3.

FIG. 1 is a block diagram showing a configuration for implementing the selection control method of the present invention, and FIG. 2 is a time chart for explaining the operation of FIG.

Data bus b8. b6=b4 two b3-b2-1. b7=
A case will be described in which the special character "tachi" out of the characters "yot1.Iltachi" corresponding to b, =b, and =o is printed.

First, data bus b8=b4=b3=b2=1. b7b5
=b1=O code to mask ROM8.

b4=b3=b2-1. The code bl-O is P, R
Input to OM9.

b, -b7=o are input to the NOR gate 5, and b6=1 is input to the NANT gate 6.

LIMT when the print head leaves the left limit position
Nt becomes °°1” and CHAR8T indicates the print digit position
Flip-flop 1 is set at the rising edge of B-Pl.

As a result, the CLR of the hexadecimal counter 2 is released and a column address is output every time one column strobe is input.

When the flip-flop 1 is reset, the output of the Nant's gate 20 becomes n 1 t+, the output of the Nant's gate 6 becomes 0'', and the CE of P and ROM 9 also becomes O''' and is written to the O address of the 1st column address. TaP, ROM9
OI+ is read from the output 0 of the flip-flop 1.
9 is set.

Every time the column address changes, a code is read from P and ROM 9, and a special character ``stand'' is printed.

When the column address becomes address 10, the flip-flop 19 is reset, the output of the Nant gate 2-0 becomes "Ott," P, CE of ROM9 becomes "1", and C of mask ROM8 becomes "Ott".
E becomes O'' and mask ROM8 is selected.

If you do not want to print special characters, either do not install that P, ROM9, or 0 of the column address of P, ROMB.
It is sufficient to write 1" in 1 bit of the address, which is used as a special character selection signal.

In the present invention, the special character is written in P, the character code is written in the ROM, and one bit of the output is used as a special character selection signal, so compared to the conventional method, 1) expensive masking is not required, 2) any special Character codes can be quickly written to P, ROM.

It is possible to achieve the following effects.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a configuration for implementing the selection control method of the present invention, and FIG. 2 is a time chart for explaining the operation of FIG. 1.

Claims (1)

[Claims] 1. A main memory in which commonly used characters are stored as a matrix pattern and the pattern is sequentially read out column by column or line by line, and a code in which special character selection bits are read out first, similar to the main memory. An additional memory is provided in which the pattern is stored as a matrix pattern added to the main memory, and the pattern is sequentially read out column by column or row by line in the same manner as the main memory, and the point matrix is read out by the selected output of either the main memory or the additional memory. For items that are printed or displayed using a font. A special character selection control method characterized in that the additional memory is selectively used when there is a special character selection bit in a code read out first in the additional memory, and the main memory is selectively used when there is no special character selection bit.