JPH019984Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a control device for a display device using a CRT or the like, and particularly to a mechanism for quickly searching attribute data on a screen buffer.

In conventional display devices, a screen buffer is provided to store screen data corresponding to one display screen. The screen buffer has addresses corresponding to display positions on the screen, and each address stores screen data such as characters and symbols to be displayed at the corresponding position on the screen. On the other hand, it may be necessary to further define the color, pattern type, and other attributes of screen data such as characters and symbols, and attribute data is used for this purpose. The attribute data is combined with screen data as necessary to cause the display controller to perform appropriate display control.

Attribute data can be stored at address locations on the screen buffer where screen data such as characters and symbols are not written. Attribute data needs to be read when inputting data to the screen, transferring data, operating the screen, etc. However, since attribute data is mixed with screen data on the screen buffer, the search conventionally involves sequentially accessing the addresses of the screen buffer, reading out the data, and checking whether it is attribute data or not. This method was carried out by examining the data one after another, which had the drawback of taking a long processing time.

The present invention aims to improve the above-mentioned drawbacks, and therefore includes a screen buffer for storing screen data displayed on the screen and attribute data defining attributes of the screen data; It has a memory plane in which one bit corresponds to each address of the screen buffer, and a binary value indicating validity at a corresponding bit position on the memory plane only when the memory content of an address in the screen buffer is attribute data. a storage means for storing position information of all attribute data on the screen buffer so that values are written;
When searching for attribute data on the screen buffer, means for creating an address of the attribute data on the screen buffer based on position information of the attribute data read from the storage means, and the created address and means for reading out attribute data from the screen buffer using a cursor address when inputting or transferring screen data based on the cursor position on the screen. A control means is provided for automatically searching for positional information of attribute data within a predetermined area on the screen buffer determined by the cursor address from the storage means, and the means for automatically searching for the attribute data is configured to a decoder means for converting the position information of the attribute data read from the storage means into an address on the screen buffer; and a decoder means for detecting whether valid position information of the attribute data has been output when accessing the storage means. a position information detecting means; when the position information detecting means detects position information of valid attribute data, it checks whether the converted output address of the decoder means is within a predetermined range; and if it is within a predetermined range; An address is supplied to the screen buffer to read the attribute data, and the position information detection means is configured to supply the valid attribute data.
and logic circuit means for controlling the conversion output of the decoder when the data position information is not detected, and specifying the next address in the storage means to access the storage means. It is characterized by:

FIG. 1 is an explanatory diagram to facilitate understanding of the embodiment of the present invention shown in FIG. 2, and illustratively shows the address correspondence between the screen buffer and the attribute table storage device. .

In FIG. 1, 1 is a screen buffer, and in this example, 1920 characters are displayed on the screen in an array of 80 characters x 24 lines. The address array of the screen buffer is shown according to the screen image, but in reality any ordinary storage device can be used. Each address has a length of 12 bits, but is shown here as a 3-digit hexadecimal number for convenience. Also, at the lowest level, 16 addresses O to F are collectively represented by X, as expanded for OBX. Each address of the screen buffer 1 can store 2 bytes of data, and either screen data such as characters or symbols or attribute data is written.

2 is an attribute table storage device for displaying the position of attribute data on the screen buffer 1; The table storage device 2 is
Expand the upper two digits of the address on screen buffer 1 from 00 to
It has 120 addresses corresponding to 78 (hexadecimal).
The word length of each of the 120 addresses is 16 bits (2 bytes), and each of the 16 bits corresponds to the least significant digit X (0-F) of the screen buffer 1 address. In the end, it will be understood that the table storage device 2 constitutes a storage plane of (120 addresses) x (16 bits) = 1920 bits, and this corresponds one-to-one with all the addresses of the screen buffer 1.

Binary value “1” in attribute table
indicates that the data at the corresponding address of screen buffer 1 is an attribute. In the diagram,
These are addresses (000), (0BE), and (751).
In particular, for the address (0BE), the process of obtaining the address of the screen buffer from the attribute table is shown.

FIG. 2 is a block diagram for explaining an embodiment of the present invention. Screen buffer 1 in Figure 2
and the attribute table storage device 2 are the same as described in accordance with FIG. 1 except that a cursor (0D7) is added.

In FIG. 2, when inputting screen data to the cursor position shown in the screen buffer 1 or transferring the data, it is necessary to read related attributes. Typically, attributes to the left of the cursor, ie, at addresses lower than the cursor address, are searched. In screen buffer 1, in order to quickly search the attribute data mentioned above,
A mechanism according to the invention is used, which is shown below the dashed line in the figure. The operation will be specifically explained below.

The upper two digits (hexadecimal) of the cursor address in the cursor address register 3 are initially sent to the table address register 5 without any action by the address-1 circuit 4. Attribute table storage 2 is accessed by the address in register 5 and reads the 16-bit word of data at that address location into data register 6. This 16-bit
The word contains information regarding the existence and position of attributes for 16 screen buffer addresses (0D0) to (0DF) that share the upper two digits (0D) of the cursor address (0D7) in the illustrated case. ing.

Data bits in register 6 are ALL “0”
The detector 7 checks whether all the bits are "0", and if all the bits are "0",
Since this indicates that the attribute does not exist there, a signal is sent to the address-1 circuit 4 via the attribute search logic circuit 8, and 1 is subtracted from the cursor address to find the attribute.
Causes the next 16-bit word of the table to be read. In the example shown in the figure, it is repeated twice from (0D) to (0B).

The attribute search logic circuit 8 has a cursor
It accepts the least significant digit (hexadecimal) of the cursor address from the address register 3 and the least significant digit (hexadecimal) of the attribute address from the decoder 9. The decoder 9 converts the bit position into a 4-bit code only when a "1" bit indicating an attribute exists in the 16-bit word in the register 6.

The logic circuit 8 compares the size of the attribute address and the cursor address, and if it is confirmed that the attribute address is correct ((0BE) in the figure), it opens the gate 10 and registers the table address register. The upper two digit address from the decoder 5 and the lower one digit address from the decoder 9 are combined and sent to the buffer address register 11 of the screen buffer.

Finally, screen buffer 1 is accessed by the address in buffer address register 11,
The desired attribute data is read.

Further, in screen data processing, when an attribute is inserted or an attribute is rewritten to screen data, the corresponding bit in the attribute table is rewritten at the same time as the data in the screen buffer is rewritten.

Although the present invention has been described in terms of embodiments using special circuit elements, many of these circuit elements can be implemented as needed by other equivalent devices, such as microprocessors. Can be easily replaced.

As mentioned above, in the present invention, extra time is required to create the address of the screen buffer compared to the conventional method, but the screen buffer is read out based on the search result of the attribute table. Thereby, the processing time for attribute detection can be significantly reduced and can be easily replaced.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram for facilitating understanding of the present invention, and FIG. 2 is a block diagram of an embodiment of the present invention. 1 is a screen buffer, 2 is an attribute table storage device, 3 is a cursor address register, 4 is an address-1 circuit, 5 is a table address register, 6 is a data register, and 7 is a
8 is an attribute search logic circuit, 9 is a decoder, 10 is a gate, and 11 is a buffer address register.

Claims (1)

[Claims for Utility Model Registration] A screen buffer for storing screen data displayed on the screen and attribute data that defines the attributes of the screen data, and one bit corresponding to each address of the screen buffer. 2, which indicates that the corresponding bit position on the memory plane is valid only when the memory content of the address with the screen buffer is attribute data.
storage means for storing positional information of all attribute data on a screen buffer in such a manner that a digital value is written; and attribute data read from the storage means when searching for attribute data on the screen buffer. A display control device comprising means for creating an address for attribute data on the screen buffer based on position information of the screen buffer, and means for reading the attribute data from the screen buffer using the created address, When performing operations such as inputting or transferring screen data based on the cursor position on the screen, a cursor address is applied and attribute data in a predetermined area on the screen buffer determined by the cursor address is retrieved from the storage means. A control means for automatically searching for position information is provided, and the means for automatically searching for attribute data converts the position information of the attribute data read from the storage means into an address on the screen buffer. a decoder means, a position information detection means for detecting whether position information of valid attribute data is output when accessing the storage means, and the position information detection means detects position information of valid attribute data. When the converted output address of the decoder means is within a predetermined range or not, and if it is within the predetermined range, the address is supplied to the screen buffer to read the attribute data, and the position information detection means Attributes with valid
and logic circuit means for controlling the conversion output of the decoder and specifying the next address to the storage means to access the storage means when the data position information is not detected. A display control device featuring: