Visual display unit and display method for a programmable computer

摘要

In a cathode ray video display unit which is designed to display graphical and alphanumeric images, the marker is made up by two orthogonal cartesian axes XAX, YAX which can be positioned by the operator or by the program. The axes have the same luminosity as the lines of the displayed image. The points of intersection P1-P5 of the axes of the marker with the portrayed lines are caused to stand out with increased brightness for the purpose of making their relative position more evident on the video unit. The coordinates of the points which stand out (X1, Y1 etc) and those of the origin of the axes (X0, Y0) may be reproduced in the form of an alphanumeric message on part of the screen. The increased brightness is commanded by a signal formed as the AND function of the signal commanding the graphical display and a marker signal which is generated at a predetermined point in every line scan and throughout the whole of one selected line scan.