Programmable timing circuit for cathode ray tube

摘要

A programmable timing circuit for a cathode ray tube includes a register stack (48) in which events to be timed are stored so that they are presented to comparators (45, 46 or 47) in the sequence in which they will occur. Each event is coded in terms of the position (character, line or row) on the screen at which it is to occur and flags stored with the values are decoded to identify the event being timed when a match is found between the presented value and the count in a character, line or row counter (40, 41 or 42) which is indicative of the current beam position on the screen. Values in the register stack can also control internal operations of the timing circuit, for example re-setting counters or re-addressing the stack.