System for developing CRT color-intensity control signals in high resolution CRT display equipment

摘要

CRT control apparatus for use in high-resolution graphic display equipment of the type including a frame buffer having storage banks for storing digital signals representing the color intensities of red, green and blue colors of pixels on the CRT screen. The control apparatus is formed in a single MOS integrated-circuit (IC) chip which incorporates three multiplexers for the three 8-bit sets of color digital signals from the frame buffer. The 8-bit outputs of the multiplexers are directed to digital-signal-transformation devices which, in response to each 8-bit signal, produce a corresponding 10-bit signal incorporating the color- intensity information of the original 8-bit signal, and also incorporating a gamma correction factor for the particular intensity represented by the original 8-bit signal. The 10-bit signals are directed to 10-bit DACs, one for each color, to produce corresponding analog control signals for the corresponding electron guns of the CRT. The 10- bit DACs include unique arrangements to minimize differential non- linearity and glitch energy at critical digital code transitions.