Vertical Window CRT Address Generator
Original Publication Date: 1987-Aug-01
Included in the Prior Art Database: 2005-Feb-01
A technique is described whereby an address generator circuit refreshes cathode ray tube (CRT) display images during active display periods and transfers character font patterns to a buffer during vertical blanking intervals. The concept is an improvement over bit plane implementation in that it minimizes memory storage requirements and provides a means of expanding CRT vertical windows. A typical alphanumeric character generating display system, as shown in Fig. 1, consists of six key circuit blocks: Regen buffer 10, which contains the character and attribute code information, horizontal row scan counter 11, address generator 12, used to refresh the image; timing sequencer 13, character generator 14, used to store fonts, and pixel processing block 15.