JPS5557936A - Crt display unit - Google Patents

Abstract

PURPOSE: To obtain a CRT display unit available for highspeed movement by providing a coordinate register which holds coordinates indicating the position of a CRT memory on a display screen and a coordinate comparator circuit which generates a signal when coordinate values exceed limit values.

CONSTITUTION: Display information from electric computer 10 is inputted to CRT controller 20 through interface 11. The information is discriminated by display controller 21 and then inputted to CRT memory 22, coordinate register 28 or memory block converter circuit 26 in accordance with its contents. Register 28 indicates what part of memory 22 should be displayed on CRT display unit 30, and information on it is supplied from computer 11 and shift signal generating circuit 40 through shift signal control circuit 27. Chaniging coordinate vlues of register 28 by a command from circuit 40 provides movements of the contents on display unit 30 in any direction. Further, coordinate comparator circuit 29 makes checks on upper and lower limits of coordinate all the time and when a coordinate is detected exceeding the limit, an interruption signal is supplied to the computer and the screen is corrected in the movement direction by a command from the computer.

COPYRIGHT: (C)1980,JPO&Japio