A General purpose terminal system included microprocessor-controlled line refresh apparatus wherein an internal address table is updated, in real time, to control the line refreshing of the CRT display; a pulse width modulated serial keyboard scanning apparatus; and smooth scrolling/double-height/double-width...http://www.google.ca/patents/US4434472?utm_source=gb-gplus-sharePatent US4434472 - General purpose data terminal system with display line refreshing and keyboard scanning using pulsewidth modulation
