JPH04134396A - Display controller - Google Patents

Abstract

PURPOSE:To make a device small-sized and high-performance by incorporating a part of a picture memory and a display control circuit, which reads out data for picture memory display, in an LSI chip. CONSTITUTION:A picture memory 12 and a display control circuit 11 are provided in a display controller chip 19. Since the picture memory 12 is in the chip, the bus width of an internal data bus 15 is extended in comparison with the case that the picture memory is provided on the outside of the chip. With respect to the display controller chip 19, the external interface consists of only video interfaces connected to a system interface control circuit 18 and a display device 14. Thus, the device is made small-sized and high-performance.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) This invention relates to a display controller used in computer equipment.

(Prior Art) Display devices used in computer equipment are required to have increasingly sophisticated functions as the core of man-machine interfaces. Typical examples include multicolor display, image display, and multi-window display, and in order to realize any of these functions, high-speed response is required of the display controller and display memory.

Conventionally, in order to display characters, graphics, etc. on a display device, a display controller and an image memory have been connected, and the display controller has controlled reading of the image memory.

Display controllers have progressed from board-level controllers assembled from individual parts to LSIs, and as display systems, image memory access performance and display controller interface bus width have become major performance bottlenecks. .

(Problems to be Solved by the Invention) As described above, conventionally, the performance of the display system is determined by the memory performance such as the access time of the external memory. Furthermore, the number of connection pins between the display controller and the image memory is not large due to the use of LSI in the display controller, and there are problems such as the memory bus width being a bottleneck in performance.

In recent years, the degree of integration of LSIs has gradually increased, and it has become possible to include large-capacity memories within the chip. Also,
Memory within a chip has the great advantage of being able to configure special types without being limited by the number of pins (memory bus width, etc.).

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a display controller that can be made smaller and have higher performance by having an image memory in a chip.

[Configuration of the Invention (Means for Solving the Problems) The present invention is an LSI chip for displaying characters, images, etc. on a display device, which stores information for displaying characters, images, etc. The LSI chip is characterized in that at least a part of the image memory for displaying the image memory and a display control circuit for reading out data for displaying the image memory are built into the LSI chip.

(Function) As described above, the present invention includes an image memory (or character font memory) that holds information to be displayed on a display device, and a synchronization signal, blanking signal, etc. necessary for displaying on a display device. By providing a display controller that performs display control for displaying data generated and stored in an image memory on a display device in one LSI chip, memory interface signals are not required and the size can be reduced. By structuring the internal image memory appropriately, high-speed processing for memory access is realized.

Furthermore, by having an image memory inside the chip, the bus width of the image memory can be expanded without being limited by the number of pins. In addition, by making the memory multi-ported, conflicts in memory access can be avoided, making it possible to speed up memory access.

(Example) Hereinafter, an example of the present invention will be described in detail using the drawings. FIG. 1 is a block diagram showing an embodiment of the present invention. In the figure, reference numeral 19 is a one-chip display controller chip that incorporates an image memory and a display control circuit that reads display data from the image memory and controls display output, and includes reference numerals 11 to 13, 15 to 15. code 1
It is composed of 7 functional elements and accesses the built-in memory to display figures, characters, etc. Reference numeral 11 denotes a display control circuit, which controls the display device 14 to generate synchronizing signals, blanking signals, etc., and to read and display data from the image memory 12.

Reference numeral 12 is an image memory that stores information necessary for display. Reference numeral 13 is a display output circuit, and image memory 12
The data read from the serial data (video signal)
and supplies it to the external display device 14. A display device 14 displays characters, graphics, etc. in accordance with a video signal output from the display output circuit 13 of the display controller chip 19. Reference numeral 15 denotes a memory data bus, which is used for data transfer of the image memory 12.

Reference numeral 16 denotes a transfer drawing circuit, which transfers a designated area to image memory data, draws figures, and the like. Reference numeral 17 is a system interface control circuit, which controls data transfer with the outside. Reference numeral 18 is a system data bus, and external data is connected to the display controller chip 19 through this bus.

FIGS. 2 and 3 are block diagrams showing other embodiments of the present invention, respectively.

FIG. 2 is a block diagram showing an embodiment in which text is displayed. In the figure, reference numeral 21 denotes a display control circuit, which controls the display device to generate synchronization signals, blanking signals, etc., and to read and display data from the image memory 22.

Reference numeral 22 is an image memory that stores information such as character codes. A font memory 23 stores font images corresponding to character codes. A display output circuit 24 converts data read from the font memory 23 into serial data and supplies a video signal to an external display. Reference numeral 25 is a system interface control circuit, which controls data transfer with the outside.

FIG. 3 is a block diagram showing an embodiment in which the built-in image memory of the display controller chip is multi-ported. In the figure, reference numeral 31 denotes a display control circuit, which controls the display device to generate synchronization signals, blanking signals, etc., and to read and display data from the image memory 32.

Reference numeral 32 is a two-port image memory that stores information necessary for display. Reference numeral 33 is a display output circuit;
The data read from the image memory 32 is converted into serial data and a video signal is supplied to an external display. Reference numeral 34 denotes a transfer drawing circuit, which transfers a designated area to image memory data, draws figures, and the like. code 3
5 is a system interface control circuit, which controls data transfer with the outside. Reference numeral 36 is a display read address, which supplies the display address from the display control circuit 31 to the image memory 32. Reference numeral 37 is an image memory address, which supplies an address for memory access other than display. Reference numeral 38 is a display data bus, and the data read out for the address 36 is supplied to the display output circuit 33 through this bus. Reference numeral 39 is a memory data bus, and data is transferred to and from the image memory 32 using an address 37.

Hereinafter, the operation of the embodiment of the present invention will be explained in detail. First, one embodiment shown in FIG. 1 will be explained.

The display control circuit 11 reads the contents of the image memory 12,
This display data is converted from parallel to serial by a display output circuit 13 to generate and output video data suitable for an external display device 14.

In addition to the display operation, the transfer drawing circuit 16 or the like transfers a specified rectangular area (BIT-BLT).

Bit-boundary Biock Transf
The image memory 12 is accessed in order to draw and fill figures such as er ), straight lines, circles, etc. Also, from the outside, the image memory 12 is accessed by the system interface control circuit 17.

The image memory 12 is inside the chip (display controller chip 1
9), the bus width of the internal data bus 15 can be made larger than that in the case where it is externally connected, and performance can be improved.

Furthermore, the display controller chip 19 can be configured with only the system interface control circuit 18 and a video interface connected to the display device 14 as external interfaces, and can be made smaller.

FIG. 2 shows an embodiment in which text is displayed. 1st
Only the display operation by a display circuit different from that shown in the figure will be explained. The display control circuit 21 reads out data such as codes and attributes from the image memory 22, reads out an image from the font memory 23 according to the code, and outputs the image to the display output circuit 24.
is converted into a video signal.

FIG. 3 shows an embodiment in which the image memory shown in FIG. 1 is made into two ports. When reading from the image memory 32 for display, the address bus 36 is sent from the display control circuit 31.
The data read out from the two-point image memory 32 is transmitted to the display output circuit 33 via the data bus 38 and converted into video output. Image memory access other than display is
This is done by separate address bus 37 and data bus 39. In this way, the image memory 32 has a feature that by having a plurality of separate address buses and data buses, it can be accessed independently and the speed can be increased.

[Effects of the Invention] As described above, according to the present invention, an image storing information for displaying characters, images, etc. on an LSI chip that performs display control for displaying characters, images, etc. on a display device. By incorporating at least a portion of the memory and a display control circuit that reads display data from the image memory, a memory interface with the image memory is no longer necessary, and miniaturization can be achieved. Also, since it is possible to have memory inside the chip, it is possible to widen the memory bus width, and by making it multi-ported, it is possible to avoid memory access conflicts and speed up memory access. .

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG.
and FIG. 3 are block diagrams showing other embodiments of the present invention. 11... Display control circuit, 12... Image memory, 13
...Display output circuit, 14...Display device, 1
5...Memory data bus, 16...Transfer drawing circuit,
17... System interface control circuit, 18...
・System data bus, one display controller chip,
22...Text memory, 23...Font memory, 32...2 point image memory. Applicant's agent Patent attorney Takehiko Suzue Figure 1

Claims (3)

[Claims] (1) At least a part of an image memory that stores information for displaying characters, images, etc. on an LSI chip that performs display control for displaying characters, images, etc. on a display device, and display data from the image memory. A display controller characterized by having a built-in display control circuit that reads out. (2) The display controller according to claim (1), wherein the LSI chip is connected to the outside without having an interface with an image memory. (3) The display controller according to claim (1), wherein a memory having a plurality of input/output ports is used as the image memory.