JPS62265694A - Cg access system - 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 [Field of Industrial Application] The present invention relates to a Ca (Character Generator) access method suitable for display units of personal computers, terminals, and the like.

[Conventional technology]

The display unit of current personal computers and the like is shown in Japanese Patent Application Laid-Open No. 57-112786.

Generally, it has two parts: a text display section that displays characters at high speed, and a graphics display section that displays graphics. An example of this is shown in FIG. 1 is a CPU, 2 is a display controller, 3 is a text memory that stores character codes,
4 is a graphic memory that stores graphic patterns. The character code 5 read from the text memory 3 is converted into character pattern information 7 by the CG 6 which stores single character patterns, and sent to the serial conversion section 81. on the other hand.

For graphic display, the graphic data 9 read from the graphic memory 4 is directly transferred to the serial converter 8.
Sent to 2. A synthesizing section 10 synthesizes these two display data and sends out a video signal 11 to a CRT or the like.

Recently, display resolution has improved and the clock speed that controls one display section has also become faster. Therefore, if CPU 1 is C
If you want to read the character pattern information of G6, it is impossible to use the cycle steal method that alternates 1 display cycle and CPU cycle, so you have to wait until the blanking period of the CRT and read the D/5P TMG signal 13, which represents 1 display period. Therefore, it was necessary to switch the address switch 12 to the CPU side to access CG6.

Alternatively, a mode called CG access mode is provided using the '10 register 14, and when the CG access mode is set, the address input of CG6 is forcibly switched to the CPU i side by the address switch 12, and the serial converter 81 There is also a method of masking the text display by controlling the CG6 and accessing the CG6 at high speed without waiting until the retrace period.

Such reading of character patterns from the CG 6 is necessary for programs such as word processors.

In other words, special display such as enlargement of characters such as single-width characters, reduction such as subscripts, and rotation such as vertical writing is not possible with the text display method, so when character patterns are expanded and displayed in the graphic memory 4. It will be held in

Furthermore, recently, a single personal computer can perform multiple processes at the same time. There are products on the market that have built-in multitasking capabilities. These products have a system line (or system message line) as shown in Japanese Patent Application Laid-Open No. 59-195745 to inform the user of the status of other processes other than those displayed on one screen. ) may be displayed in one or two lines at the top or bottom of the screen.

An example of this is shown in FIG. 15 is a user screen area, and 16 is a system line.

[Problem that the invention seeks to solve]

The system line 16 is displayed as text due to memory capacity, but if the system line 16 is displayed using the CG access mode described above,
When an attempt is made to access G6, the display of the system line 16 based on the 7" text also disappears, making it impossible to notify the user of important information such as errors.

Alternatively, waiting to access CG6 until the retrace period to prevent the display on system line 16 from disappearing slows down the execution speed of a word processor, etc., and is problematic in multitasking processing that requires an immediate response to one interrupt. There is.

In order to prevent such problems, it is conceivable to display the system line 16 using a graphic display. As an example, if we consider a general case where the display of the user screen area 15 is 25 lines with 16 rasters per line and 80 characters with 8 dots per character horizontally, the number of displayed dots of the graphic is horizontal (soxs) x Vertical (16 x 25) = 640 horizontal x 4 vertical
It becomes 00. The capacity of the graphic memory 4 required for this is 640 x 400 ÷ 8 ÷ 1024 == At
It is 25 kB. If you add one system line 16 to the bottom as shown in Figure 2, the vertical line will be 2.
In order to have 6 lines, the display dots of the graphic are 64 horizontally.
0 x 416 vertically, and the required graphic RAM capacity is 640 x 416 ÷ 8 ÷ 1024 = 52.5k
It becomes B. On the other hand, to graphics RAM4.

1) RAM (dynamic type RAM) of 16kh x 4
), it will be 52kB with 4 pieces, but if you use 8 pieces and display 16'@:
52.5kB of the kB will be displayed. Thus, displaying the system line 16f by a graphical display is inefficient in memory usage.

In order to solve these problems, an object of the present invention is to access the CG 6 at high speed without significantly increasing the memory for displaying the system line 16.

[Means to solve the problem]

The above purpose is to display the system line 16 display as text, and to erase only the text display in the user screen area 15 even if the CG access mode is set, so that the display of the system line 16 and the access to the CG 6 by the CPU 1 are This is achieved by placing a wait on the CPU 1 only when the numbers overlap and making it wait until the retrace period.

[Effect]

In the present invention, since the display of the system line 16 does not disappear even in the CG access mode, the user can always be informed of information on the system side.

In addition, the display of the system line 16 and the C
Way i until the retrace period only when G6 accesses overlap
However, during the period when system line 16 is displayed,
Since the time is as short as about 1/30 of one vertical scanning period of a CRT, etc., the influence of the wait caused by accessing CG6 is also reduced on average. Therefore, problems such as a slow execution time of software such as a word processor or a delay in response to an interrupt do not occur.

〔Example〕

The present invention will be explained in detail below. Figure 1 is.

This is an example of an embodiment, and the difference from the conventional example shown in FIG.
``A decoder 18 that detects the boundary of the area where only the text surface is displayed, and a decode signal 19 output from the decoder 18.
This is the addition of a weight generation circuit 21 that generates a weight signal 20 for the CPU 1 based on.

Here, the user screen area 1st 1'' 80 characters horizontally x 25 lines 2
000 characters, and the system line 16, which is an area where only the text screen is displayed, has 80 characters (80 horizontal characters x 1 line). And the address of text memory 3 is ooooH~o7c
It is assumed that pg (x is an abbreviation for Has and represents a hexadecimal number) corresponds to the user screen area 15 and 0800H to 084 FH corresponds to the system line 16.

FIG. 3 shows an example of the weight generation circuit 210.

The decoder 18 is not particularly necessary in the example of address assignment described above, and by using the MA1D signal 171 of the 11th bit of the display address 17 as the decode signal 19, it is possible to know the magnitude of the address relative to osooH.

FIG. 4 is a timing chart illustrating the operation of the weight generation circuit 21 shown in FIG. I10 register 1
If the CG access mode is set by 4, C
The GAMODE signal 22 becomes L°. System line 1
6 is displayed, the MA10 signal 171 is "Ho," and when the DISPTMG signal 13 is 1H°, that is, during the display period, when the CPU 1 accesses the CG6, the memory access signal MRIP' 25 and the CG chip select The signals CGC 524 each become active, and the WAIT signal 20 becomes "L" to put a wait on the CPU 1. After that, in the non-display period (retrace period), when the I) ISPTMO signal 13 becomes °L°, 1f'
The AIT signal 20 becomes °H0, and the weight of the CPU 1 is released.

On the other hand, if an access occurs from CPU 1 while displaying user screen area 15 or during a non-display period, W
Since the AIT signal 20 does not become "L", CG6 can be accessed at high speed.

In this example, if the CG access mode is not set, the address switch 12 does not switch to the CPU 1 side until the non-display period, so there is a period in which the CPU 1 cannot access the CG 6. Therefore, 1. For example, a certain I10 boat has a DIS
Connect the PTMG signal 15, and before accessing CG6, CPU 1 first reads this I10 port, waits for the DISPTMG signal 15 to enter the non-display period state, and then accesses CG6. . Alternatively, when not in the CG access mode, the CPU 1 may be weighted by the weight signal 20 output from the weight generation circuit 21 until the non-display period whenever the CG 6 is accessed.

Although the above description has been made regarding the case where the system line 16 is displayed, it may also be applied as an area for displaying a partial text screen displayed as a work for kana-kanji conversion, for example.

Similarly, the present invention may be applied to a case where a part of the background jog during multitasking operation is displayed by dividing one screen.

〔Effect of the invention〕

As described above, according to the present invention, Ca can be accessed at high speed without preparing a large capacity graphic memory for the system line and without erasing the display of the system line.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention. FIG. 2 shows an example of a screen displaying the system line 16, FIG. 5 shows an example of the weight generation circuit 21 shown in FIG. 1, and FIG. 4 shows its timing chart. FIG. 5 shows a conventional example. It is a diagram. 1 ・・・・・・・・・・・・ CPU2・・・・・・
・・・・・・Display controller 3・・・・・・・・・・・・
...Text memory 4...Graphic memory 6...CG 12...Address switch 14...・
・・・・・・I10 Register 18・・・・・・・・・Decoder agent Patent attorney Masaru Ogawa 1st son X i ■ 3 2 Ki 33 Kohiro 4 Takumi

Claims (1)

[Claims] 1. A CPU that controls the system, a text memory that stores character codes, and a text memory that stores character codes;
In a display system comprising a text display section that is converted into a character pattern by a generator (CG) and displayed, and a graphics display section that has a graphic memory that stores figures to be displayed as bits and patterns, the display screen is divided and a first A graphic screen is displayed in the display area, a text screen is displayed in the second display area, and when the first display area is displayed, the address input of the CG is connected to the address path output by the CPU. and when the second display area is displayed, the address input of the CG is connected to the output of the text memory. 2. When displaying the second display area and when the CP
2. The CG access method according to claim 1, wherein when accesses from U to the CG overlap, the CPU is given a wait until a non-display period.