Multiple character set generator for CRT display - uses camera to scan artificial grid elements on image and stores contents of each element in alternative character set RAM

摘要

An image is reproduced on a cathode ray screen using a video camera and a visual display unit having a facility to enter an alternate character set into random access memory. A microprocessor with a keyboard input controls the display using a text memory and a display functions memory. Both memories are normally connected via an electronic switch to a fixed character set generator with a read only memory (ROM), which drives the cathode ray tube via an OR gate. A specified key on the keyboard instructs the microprocessor to switch the signals to the alternate character set held in RAM. If an image is to be reproduced it is divided into a square grid and the part of the image located in each grid is detected by the video camera and stored in the alternate character RAM as appropriate dot matrix elements for the character formation.