JPS63236087A - Character generator - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention [Summary] In order to use memory efficiently in a character generator, the present invention divides an empty area into two blocks, and divides the bit pattern in the odd address part of a character pattern into one block. The bit pattern in the even address part is written to another block, and the contents are read out alternately in block units.

[Industrial application field]

The present invention relates to a character generator.
In particular, it relates to a character generator configured using a 4M focus mask ROM.

Conventionally, character generators used several 1M bit masks l'lQM, but as 4M bit mask ROMs became more practical, there was a demand for character generators to be constructed using one 4M bit mask ROM. It's here.

[Conventional technology]

Fig. 4 is a block diagram of a conventional character generator, and Fig. 5 is a conventional 4M bit mask RO? It is a character pattern assignment diagram of I.

In FIG. 4, 41 is a character code designation section for specifying a character that the operator wants to read out of the plurality of characters stored in the mask ROM 44, and 42 is a divided block of characters designated by the character code designation section 41. 43 is a scan counter that specifies atlas and dots in the block specified by the block specification section 42; 44 is a mask ROM storing a plurality of characters; 45 is a mask ROM 44 to 8-bit mode; Byte information input to the mask ROM 44 for switching the output or 16-bit mode output, 46 indicates A and B output from the mask ROM 44.
A multiplexer (hereinafter referred to as MPX) that selects a code using a selection signal is shown.

When writing a character pattern to the mask ROM 44, as shown in FIG.
Since it is soto, 24X, which is usually used in this area,
Write the entire 24-dot character pattern.

Furthermore, the empty area created to write a 24 x 24 dot character pattern in the 32 x 32 dot area, that is, the address "ooooo" of block 1.1 101
11'' is the central block required when reading 12 bits x 2 times as described below (here, the address of block 0.1 is ``oooooo'' to ``10111'').
Write the same content twice as is.

When reading a 24 x 24 character pattern from the mask ROM 44, if 8 bits x 3 times, 16 bits x 1 time + 8 bits x 1 time, 8 bits x 1 time + 16 bits x 1 time, etc., read the same as before. For the mask ROM 44, the character code designation section 41. By sending signals from the block specifying unit 42 and scan counter 43, and inputting hide information 45 to the mask ROM 44, for example, if the byte information 45 is "0", 8-bit mode output, If it is "1", it can be switched such as 16 bit mode output, and various readings can be performed.

Also, if you want to process bit data in two parts on the processing device, that is, if you want to read out a 24x24 dot character pattern in two parts of 12 bits each,
MPX 46 is installed on the output side of mask ROM 44,
In the mask ROM 44, the 16-bit mode is used with the byte information "1", and only 12 bits out of 16 bits are read out, and during the first read, block 0.
First, 12 bits from D8 to D1 of the address "ooooo" of block 0 and from 016 to 013 of the address "ooooo" of block 0.1 are read out and used as the A code.

When reading for the second time, address of block 1, 1”
Read the 12 bits from D12 to D9 of "oooooo" and from D8 to Di of the address "ooooo" of block 1.0, and use this as the B code. The MPX 46 selects either the A code or the B code based on a selection signal which is an external signal.

Thereafter, by repeating the above operation, 12 bits
A character pattern is formed by reading twice.

[Problem that the invention attempts to explain]

However, when writing one character pattern into a 4M bit mask ROM, areas are allocated to each character pattern in units of powers of two in order to facilitate decoding. Therefore, for the normally used character pattern of 24 x 24 dots, an area of 32 x 32 dots is allocated, resulting in an empty area of 8 x 32 dots. The purpose of this invention is to provide a character generator with improved problems.

[Means for solving problems]

FIG. 1 is a diagram showing the principle of the present invention.

The present invention divides an empty area a generated by writing a character pattern with an arbitrary number of dots into two blocks, and in one block 2, odd-numbered addresses of character patterns with a smaller number of dots than the character pattern with an arbitrary number of dots are written. A memory 1 in which the bit pattern in the even address part is written in the other block 3, a block specifying means 4 for alternately specifying the two blocks, and an address in the block 2.3. The configuration includes an intra-block address designating means 5 for designation.

[Effect]

With the above configuration, the present invention utilizes the empty area created by writing a conventional character pattern to write a character pattern with a smaller number of dots than the conventionally written character pattern, for example, a 16×16 dot character pattern. On the other hand, for reading, the block specifying section 4 alternately specifies blocks 2 and 3, and the intra-block address specifying means 5 specifies the address within the block, thereby reading the bit pattern alternately from each block. By doing this, any character pattern can be formed.

〔Example〕

Hereinafter, one embodiment of the present invention will be described in detail using FIGS. 2 and 3.

FIG. 2 is a diagram showing an embodiment of the present invention, and FIG. 3 is a diagram showing an embodiment of the present invention.
It is a diagram showing the configuration of a 6×16 dot character pattern.

As shown in Figure 2, in a 4M bit mask ROM, the area allocated for one character pattern is 32x32.
Since it is a dot, for example, an entire 24 x 24 dot character pattern is written in one mask ROM in this area, and a 24 x 24 dot character pattern is written in a 32 x 32 dot area. For example, the third
Write a 16x16 dot character pattern as shown in the figure. To write this 16×16 dosoto character pattern, the empty area is divided into two blocks. For example, in the left block, the 16×16dosoto character pattern 110000″ and “110010” shown in FIG. 3 are written.

AO writes "0", that is, the bit pattern at an even number address, and the right block contains 16x16 characters (7) "110001",
"110011".

The lowest pinpoint 80 of an address such as "110101"... writes "l", that is, a bit pattern of an odd address.

By writing as above, the 16 x 16 dot character pattern is masked.
It can be converted into a character pattern of ×32 dots.

16X converted to 18,000 x 32 dot empty area and written
When reading out a 16-dot character pattern, an address within the block is designated by a scan counter 43 as an intra-block address designation means as shown in FIG. For example, if the address "11000" is specified, either the left or right block is specified in the block specifying section 42. For example, if the right block is specified, the bit pattern written in the right block is read out. Next, the output ("11000") of the address designation part in this block is left as is, and the left block is designated by switching the output of only the block designation part, and the bit pattern written in the left block is read out. When the bit pattern of the same address in the left and right blocks is read,
By amplifying the output of the scan counter 43 by +1 and specifying the address "11001", the block specifying section 42 alternately specifies the left and right blocks as described above, and reads out the bit pattern written in the block. By repeating the count up by +1 up to the address "11111", the 16x16 dot character pattern written in the 8x32 dot empty area can be read out.

〔Effect of the invention〕

As explained above, according to the present invention, the mask ROM can be used without waste by writing different dot character patterns into the empty area of the mask ROM.

[Brief explanation of drawings]

Fig. 1 is a diagram showing the principle of the present invention, Fig. 2 is an embodiment of the present invention, Fig. 3 is a diagram showing the configuration of a 16 x 16 dot character pattern, and Fig. 4 is a diagram of the conventional character pattern. FIG. 5 is a block diagram of a character generator; FIG. 5 is a character pattern assignment diagram of a conventional 4M focus mask ROM. In the figure, 1-memory, 2.3--block, 4-block specifying means, 5-block address specifying means, 41-character code specifying section, 42-block specifying section, 43-scan counter, 44-mask ROM , 45- byte information, 46- multiplexer (MPX). x/6 Daunt's Civilian Pattern Hanawa Tsume L Convex% 37b No. 1 for every 4 pieces of the earlator's reservoir, which is used as a tattoo for a long time 54
゛Zurin 8 Kei's 4 Δ Bisotomazufu RO Relais and Zu Ryo Pa Gaina 1st time 145
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Claims (1)

[Claims] Divide the empty area (a) created by writing a character pattern with an arbitrary number of dots into two blocks, and fill one block (2) with an odd number of character patterns with a smaller number of dots than the character pattern with an arbitrary number of dots. A memory (1) in which a bit pattern in an address field is written and a bit pattern in an even address field is written in the other block (3), a block designating means (4) for alternately designating the two blocks, and a block designating means (4) for alternately designating the two blocks; ), (3).