Abstract: A video RAM write control circuit has a video RAM for storing pattern data of one frame at addresses thereof which correspond to display positions, and a control circuit for generating write pattern data and write addresses. The video RAM stores a pattern which is continuous in the horizontal direction, at consecutive addresses thereof. Each row on the screen consists of several rasters. A video RAM address has a memory address representing a position in the horizontal direction, in its lower bits, so well as a raster address representing a raster position of the row, at upper bits thereof. A write address is rotated toward the MSB by the number of bits of the raster address, and a resultant permuted address is supplied to the video RAM.

Abstract: A video display control system displays a multicolor animation pattern on a screen of a video display unit. The video display control system is mainly constructed by a video RAM (VRAM) and a video display processor (VDP). The VRAM stores animation pattern data, display position data and at least two color data. The VDP reads these data and makes an animation pattern image displayed in at least two colors at a display position on the screen. The animation pattern image, two colors and display position are determined by the animation pattern data, two color data and display position data. In another video display control system, the VRAM stores at least two sets of animation pattern data, display position data and color data. When displaying two animation patterns, the VDP effects a logical operation on the two color data with respect to the overlapping portion of the two patterns and makes the overlapping portion displayed in a new color corresponding to the operation result.

Abstract: An image display apparatus reads color data and attribute data accompanied with the color data from a RAM of a look-up table (LUT) in accordance with each color code read from a video memory (VRAM). The read color data is subjected to a data modification determined by the read attribute data, and a color of each display dot is determined in accordance with the color data obtained as the result of the data modification. According to this image display apparatus, an image and the color thereof can be displayed without storing all the color codes of the image into the VRAM, so that the load on the CPU can be reduced and the image can be displayed at a high speed. The LUT can be omitted by storing, correspondingly to each display dot, display data composed of color data and attribute data in the VRAM. The circuit for effecting the data modification may comprise a plurality of registers and an operation circuit for effecting an operation on data contained in the registers.

Abstract: An interface circuit can assign a common input/output port address to a plurality of I/O circuits. Each common I/O port is defined in terms of pages. In an actual data input/output, a specific port address is used for port control so as to select one common page. The interface circuit has a first decoder for decoding a specific port address signal. The interface circuit also had a data setter for setting data supplied from a specific bit line of the data bus. The data is set in the data setter in accordance with the decoded signal from the first decoder. Each of the plurality of I/O circuits has a second decoder for decoding the common I/O port address signal. An output from the setter enables a corresponding one of second decoders. As a result, a specific page is selected.

Abstract: A display controller can display a cursor having sufficient contour irrespective of the background color. The display controller has two cursor pattern memories from which first and second cursor patterns are read in such a timing that the first cursor pattern is displayed at a selected position on the screen and that the second cursor pattern is superimposed on the first cursor pattern. The display controller also has two registers storing therein first and second color codes corresponding respectively to the first and second cursor patterns. The color of the first cursor pattern is determined by a color code obtained by subjecting the first color code and a background color code read from a video memory to a logical multiplication, and the color of the second cursor pattern is determined by a color code obtained by subjecting the color code of the first cursor pattern and the second color code to an exclusive-OR operation.

Abstract: A display control system has a digital interface therein. When software using a color display is executed and displayed in a monochrome monitor, this system is responsive to color code information to arbitrarily select either a hatching pattern conversion or a grey scale display according to application software or the like. The system can thus discriminate the display contents thereof.In a color monitor that permits input of a plurality of digital signals, the display control system can convert a given piece of color code information into digital video signals according to frames and display positions in a given area of a display screen for display of natural colors.

Abstract: A pattern write control circuit of the invention has a graphic memory consisting of a plurality of memory planes each storing corresponding to color data for color display, an address selector for supplying a common address to the plane memories, a register storing the color data corresponding to each memory plane and simultaneously supplying the color data to a common location of the memory planes accessed by the common address, and a decoder for producing write enable signal for writing the color data into a specified memory plane in accordance with the display color data of the dot supplied from a CPU.

Abstract: A video display processor (VDP) is connectable to an input control device such as a light pen and a mouse. The VDP comprises a counter circuit which is composed of an X counter and a Y counter. When a mouse mode is selected, X and Y pulse signals are supplied to the X and Y counters so that the contents of the X and Y counters represent the amount of movement of the mouse. When a central processing unit (CPU) connected to the VDP reads the contents of the X and Y counters in this mouse mode, the X and Y counters are reset. When a light pen mode is selected, the X and Y counters effect a count operation of a clock signal generated in the VDP in synchronism with the display of image on a screen so that the contents of the X and Y counters represents X-Y coordinates of a display element which is currently displayed on the screen.

Abstract: A video display control system displays a video image composed of a plurality of display elements on a screen of a video display unit. The system comprises a memory (VRAM) for storing a plurality of color codes each representing at least one display element and a video display controller (VDP). The VDP comprises a mode register for selecting one of normal display and transparency processing modes, display processing circuit for reading the color codes from the VRAM, a backdrop color register for storing a color code such as one representing a backdrop color, a detection circuit for detecting a predetermined color code from the color codes read by the display processing circuit, and a selector controlled by an output of the detection circuit. In the normal display mode, the selector outputs all color codes read by the display processing circuit to the display unit.

Abstract: A color video display apparatus displays a first image represented by luminance and color difference data stored in a VRAM and a second image represented by color codes stored in the same VRAM on a screen of a CRT display unit in a superimposed relation. Each address of the VRAM stores the luminance data and an attribute bit of the corresponding display dot of the first image, and the color difference data is formed with respect to each group of a predetermined number of display dots of the first image and stored in a predetermined number of addresses of the VRAM. The color code of each dot of the second image is stored in the corresponding addresses of the VRAM. The data sequentially read from the addresses of the VRAM are shifted into a register group composed of a predetermined number of registers.

Abstract: A display control system can implement a gray-scale display of an image composed of a plurality of display dots on a display screen. A plurality of luminance data each representing an intensity level of a corresponding one of the plurality of display dots are first generated. Each luminance data is then converted into a pulse signal whose pulse number corresponds to an intensity level of the corresponding display dot represented by the luminance data. And, each display dot on the display screen is activated in accordance with a corresponding one of the thus produced pulse signals. To eliminate flicker of the display dots, the display dots on the display screen are grouped into a plurality of display sections each composed of a predetermined number of adjacent display dots, and if the display dots in one display section are equal in intensity level, these display dots are activated by the pulse signals which are equal in pulse-number but different in phase.

Abstract: A display controller displays an image on either of a CRT display unit and a liquid crystal display unit (LCD) having upper and lower screens in accordance with image data stored in a memory. When a CRT display unit is driven, an address generating circuit calculates at the beginning of each horizontal scanning an address of the memory corresponding to the leftmost display position on the current horizontal scanning line in accordance with the vertical position of the horizontal scanning line and the number of display positions on a horizontal scanning line, and stores data representing the address in a first register. The data in the first register is incremented in accordance with the horizontal scanning and fed to the memory to read the image data.

Abstract: A display controller which can display a cursor on either of a CRT display or a liquid crystal type display device is described. The liquid crystal type display device is a type that has an upper and lower display blocks which are scanned substantially in parallel. This display controller allows the display position of the cursor to be designated in the same manner, independent of the type of display device used. The display controller operates in a time sharing manner, alternately on the upper and lower display blocks of the liquid crystal device. Two groups of data corresponding to these upper and lower blocks are formed and are supplied to the liquid crystal display device substantially in parallel. X and Y coordinate positions of the cursor position are also stored. The cursor pattern signal for the liquid crystal display device is also stored in a time shared manner.

Abstract: An improved display control system for use in a computer is disclosed which is equipped with functions of X, Y addressing and area movement so as to reduce the execution time necessary for display operations of the computer. Also, in this display control system, means for executing line commands is composed of the hardware so as to reduce the execution time necessary for display operations on the line commands.

Abstract: A video display processor (VDP) produces a video signal by which a black and white image of an increased gradation can be displayed on a video display unit. The VDP reads from a video RAM (VRAM) either color codes each representative of a color of each display element, or amplitude data representative of amplitudes of a video signal to be reproduced. When displaying an image based on the color codes, the color codes are converted by a color palette circuit into color data each composed of three primary color data, and then supplied to a digital color encoder. The digital color encoder multiplies each of the three color data by predetermined coefficients at proper phase timings to output data representative of three chrominance signals. This output data is summed by an adder circuit and then converted into an analog signal to be supplied to the video display unit as the video signal. When displaying an image based on the amplitude data, the color palette circuit converts the amplitude data into gradation data.

Abstract: A display control circuit comprises dynamic memory chips as a video RAM for storing pattern data or character codes to be displayed on a screen, and a read controller for generating a reading address (including a raster address and a memory address). For refreshing all memory cells for the dynamic memory chips within a predetermined refresh period, the circuit further comprises an address converter for supplying a part of the raster address and a part of the memory address to a row address of the memory chips and for supplying all or a part of the remaining reading address to a column address thereof so that a part of the raster address is assigned to the lower bit location of the row address.

Abstract: There is provided a video display controller which can vertically and horizontally shift a whole video image displayed on a screen of a video display unit. The video display controller comprises an image data read circuit which reads the image data from a video RAM, a register into which data representative of amount of shift of the video image is stored by a central processing unit, and a first counter which cyclicly counts a clock signal. An adder adds the data contained in the register and a count output of the first counter, and at a timing determined by this addition result a predetermined value is preset into a second counter. This second counter counts the clock signal from the predetermined value, and the image data read by the image data read circuit is outputted to the video display unit at a timing in accordance with a count output of this second counter. The register, first counter, adder and second counter are provided in each of vertical and horizontal scanning control circuits.

Abstract: An inexpensive A-D converter circuit comprising a signal conversion circuit for converting an analog signal into a digital signal based on a reference voltage, in which the whole reference voltage is varied periodically, the output signal just ahead of the signal conversion circuit is held by an output buffer, and the output signal of the signal conversion circuit and the signal just ahead are added. Also, in the A-D converter circuit, after the above addition, a difference between two consecutive pieces of data of the output data of the signal conversion circuit is detected. When the data difference is within a given range, then the output of the above addition is selected, while for the data difference exceeding the given range double the above output is selected.

Abstract: A video display control system for displaying a video image on a screen of a video display unit. This video display control system basically comprises a VRAM (video RAM) and a video display processor (VDP). The VRAM has memory locations corresponding to display elements on the screen. The VDP includes a first register for receiving area information identifying a display area on the screen, an address generator for generating addresses of memory locations corresponding to the display area in accordance with the area information, and a memory accessing circuit for accessing the memory locations having the addresses. Therefore, the memory accessing operation through this VDP does not need a complicated support by a central processing unit. The VDP further comprises a second register for storing a color code supplied from an external device or read from the VRAM.

Abstract: A video RAM write control apparatus cmprises a video RAM of byte access for storing dot pattern data, and a write circuit for supplying write data of one byte and a write enable signal to the video RAM. The video RAM includes n (n being an arbitrary natural number) memory blocks, each consisting of 1 bit.times.N addresses, the same address being assigned to the n-bits word. The write circuit includes a bit mask register in which an n-bit bit mask pattern data having a flag in a specific bit is set, and NAND gates for supplying AND signals of an output of each bit of the bit mask register and a write enable signal to the write enable terminal of each memory block.