Abstract: There is disclosed a circuit and method for providing a reference voltage to a matrix array of video DAC cells. The circuit is located substantially within a center of the matrix array in order to minimize any effects upon the delivered reference voltage that process variations within the integrated circuit supporting the video DAC may produce. The center location minimizes the average distance between the voltage reference circuit and each of the DAC cells within the matrix array. In a preferred embodiment, the circuit is divided so that a reference voltage supplied by one portion of the circuit is unaffected by inherent capacitances within the MOSFET devices utilized within the circuit coupling that voltage reference to the other reference voltages supplied by the second portion of the circuit.

Abstract: A pixel processor is disclosed which is comprised of a video window generator (VWG) (10). VWG (10) utilizes a conversion section for receiving an input video signal in a YUV 422 video format and converting it to an RGB video format. The conversion section includes a chroma interpolator 56 for converting the YUV 422 video format to a YUV 444 video format, a color converter (58) for converting the YUV 444 video format to an RGB video format, and then to a gamma coding removal block (60) for removing gamma coding. After conversion, the RGB video format signal is then scaled down by a linear resampler block (62) to average information over a predetermined portion of the input display space for output to a predetermined portion of the output display space. The scaled video output is truncated by a quantization processor (64) and then input to a FIFO (66). A control unit (68) controls the operation of the system.

Abstract: A quantization processor (64) is provided that is operable to provide an error diffusion for adjacent output pixels in an output display space. Three quantization processors (300), (302) and (304) are provided for the three colors of the video RGB format. A full adder (312) is provided for receiving both an error signal and an input pixel value. The composite output is input to an input/output error register 328 that is operable to store bits of the output of the adder, determined to be output bits, and also to store the remainder of the bits that are determined to be error or truncated bits. The error or truncated bits are fed back to the input of the full adder. A rounding decoder (306) is operable to receiving a masking word, such that the outputs from the register (326) are either selected as bits to be truncated, provide an error to be added to the next sequential pixel value, or they are selected as outputs. The register (326) is operable to store the error bits for the next sequential cycle.

Abstract: There is disclosed a system and method of controlling the timing in a system having a number of different elements, each requiring individual timing signals. The system utilizes a RAM memory divided into a number of groups or cycle types, each cycle type having a number of addressable words. The individual bits of each word serve to control the individual system elements. The memory is programmed to allow each group of words to control the system timing in a different manner. Provision is made for the memory to skip certain words in a particular group under control of externally provided signals.

Abstract: There is disclosed a memory controller for controlling addresses to a plurality of different memory types while treating the memory system as a whole so as to create a unified addressing arrangement. The controller is structured to allow for a reprogramming of the split address between the memories and for maintaining contiguously addressed locations. A register is used to hold the split address and the register can be updated at initialization to vary the split depending upon physical memory changes. The controller also maintains a common bit length addressing word regardless of the memory size being addressed by the system processor.