Abstract: A video monitor operable in either a 16 or 64 color mode includes a PROM having logic level color video inputs and logic level function inputs, including a mode select input, for accessing different memory locations at each of which binary data is stored for activating a plurality of logic level color video outputs. A plurality of analog R, G and B processing circuits are coupled to the PROM outputs, with their gains being controlled by the color video signals supplied from open collector connected outputs in the PROM. The gains are user adjustable by means of logic level driven analog circuits. The horizontal scan frequency differs in the two modes and a mode switched brightness compensation output is provided by the PROM.

Abstract: A video terminal is capable of operating with three different vertical formats which are determined by the polarities of the incoming horizontal and vertical sync signals. A PROM is supplied with address inputs corresponding to the different combinations of incoming vertical and horizontal sync signal polarities and signal levels, and outputs comprising mode selection signals and horizontal and vertical sync pulses of given polarity for use by the monitor.

Abstract: A color video switching circuit comprises a first and a second emitter-follower transistor receiving color video input signals from different sources and being connected at their emitters to a pair of oppositely poled diodes having a junction connected to a common output terminal. An AND gate and an inverter are coupled to the emitters of the transistors for applying complementary voltages thereto to simultaneously bias one transistor into saturation to preclude passage of its associated color video signal to the output terminal and bias the other transistor into its active region for coupling its associated color video signal to the output terminal. The diode associated with the saturated transistor is also back-biased to enhanced isolation of the non-selected video signal from the output terminal.