Apparatus and method for testing and verifying the timing logic of a cathode ray tube display

摘要

A data processing system includes a cathode ray tube (CRT) display. Apparatus associated with the CRT tests and verifies the vertical and horizontal synchronization and the logic associated with a character generator. Refresh signals, horizontal synchronization signals and data bit signals from the character generator are counted. The counts of those signals which occur within a predetermined number of occurrences of vertical synchronization signals are verified.