JPS6474596A - Multiplex display controller - Google Patents

Abstract

PURPOSE: To detect specified picture information from display data read out from a display memory, to selectively control writing operation based on the detected result and the state of superscription instruction, and to selectively use the specified picture element information used for the detection as effective color information. CONSTITUTION: A basic picture display position information generation circuit 6 generates display position information on a scanning line on the screen of a CRT. When the display data for a basic screen becomes complete, a multiple picture processing signal is activated and the display operation of a multiple signal is started. An address selection circuit 17 reads out the output of a retrieval counter 9 in order of the attribute information of an attribute memory 3, detects a multiple picture, and performs the write-control 10 of a superscription instruction signal from the memory 3. In the case the display data read out from the display memory 2 is edited in an editing memory 4, prioritization and the control of a display state are performed by the control circuit 10. The data read out from the memory 4 is parallel-serially converted by a video data register 13 and supplied to the CRT 15 through a video generation circuit 14.