WINDOWING AND SCROLLING FOR A CATHODE-RAY TUBE DISPLAY

摘要

WINDOWING AND SCROLLING FOR A CATHODE-RAY TUBE DISPLAY A method and a circuit for producing an independent scrollable display region (sometimes referred to as a "window") on the face of a cathode-ray tube (CRT) in a bit-mapped data display system is disclosed. Circuitry is provided to detect the presence of the window along a vertical axis and to detect the presence of the window along a horizontal axis. When both a vertical and a horizontal presence are detected simultaneously, a window is deemed to be present. When the window is deemed to be present a memory address selection circuit selects memory addresses from one memory address circuit and when the window is deemed to be not present, the memory address selection circuit selects memory addresses from another memory address circuit.