A circuit and method for displaying characters in a point matrix on a video screen raster with improved resolution utilizes first and second character generators each storing a portion of the character points to be displayed. Each character generator provides an input to an associated shift register, and the shift registers are controlled by complementary clock pulses so that the outputs are shifted by one-half of a bit representing a character point in the matrix. The outputs of the shift registers are combined in a mixer to provide a single output having twice the resolution power of conventional units but without increased band width.
A computer video demultiplexer for combining a plurality of low resolution, video input signals into a plurality of higher horizontal and vertical resolution video output signals. Control signals for the video demultiplexer are coded on non-displayed video scan lines which are uniquely addressable so that several demultiplexers operated from one video signal may control a number of high resolution peripheral devices.
A video graphics controller circuit for a personal computers includes a standard, EGA-compatible graphics adapter and a high-resolution companion module. A method is disclosed for configuring the graphics adapter is to generate 2 pixels in parallel in each clock cycle. The companion module serializes the pixels to generate a serial stream of pixels at twice the frequency of the graphics adapter. The companion module can also be configured as a video line driver so that the graphics controller circuit can also run software in standard video modes.
A method and apparatus are provided for increasing the number of characters or symbols that can be displayed on a line when the video signal that produces the display is restricted to a limited bandwidth, such as in the case of RF modulating the video signal to produce the display on an unmodified television set. The bandwidth of the video signal is reduced by displaying different portions of the display during one field time and the remaining portion of the display during the next field time. The persistence of the television screen creates the illusion of a complete display. Each luminescent region of each line will be displayed during one field time and blanked during the next field time. In the preferred embodiment, adjacent luminescent regions of a scan line (e.g., separated only by a black region) will be displayed in opposite fields. In an alternative embodiment, adjacent character regions will be displayed in opposite fields. The invention is compatible with standard and high definition television receivers.
A video display memory expansion system for expanding the graphics memory within the video display. The memory expansion system is suited for increasing the resolution of a graphics display from a low-resolution to a high-resolution display. A video display device is adapted to receive a relatively simple graphics memory expansion accessory to thereby easily and inexpensively provide the increased graphics memory capability.
