Abstract: An apparatus for providing precise convergence compensation in a shadow mask type color CRT display. Coarse compensation is provided by the coefficients of primary terms x.sup.2, y.sup.2 of the beam's longitudinal and vertical position polynomial in an analog format, and fine compensation is provided by digital programmable read-only-memories. The fine compensation is representative of the precise values of the coefficients of the remaining terms in these polynomials, and a digital-to-analog converter converts the fine compensation to an analog format. The coarse and fine data are summed together and applied to the convergence correction coils of the CRT.

Abstract: A cathode ray tube linear beam deflection system capable of operation over a wide range of beam deflection rates providing automatic power supply voltage switching to maintain linear operation and provide minimum power dissipation. Information for the automatic switching is obtained by continuously monitoring the yoke voltage, the power supply voltage being switched to a voltage of higher magnitude when the yoke voltage exceeds a predetermined level and returned to the power supply voltage of lower magnitude when the higher magnitude voltage is no longer required.