公开(公告)号：DE3782830T2

公开(公告)日：1993-06-09

申请号：DE3782830

申请日：1987-01-08

Applicant: IBM

Inventor： RAHIM OMAR MAHMOUD ,  KWONG EDWARD YUMAN ,  IIDA YOSHIO ,  ELSNER MATTHEW

IPC: G09G5/36 ,  G09G5/00 ,  G09G5/02 ,  G09G5/06 ,  G09G5/393 ,  G09G5/395 ,  G09G1/28 ,  G09G1/16 ,  G06F3/153

Abstract: A colour graphics display having a read/write control system for a buffer memory therein provides Line-on-Line and Underpaint mode operation, if selected and enabled, by reading the contents of a frame buffer storage location for which new pixel data is being provided, comparing those contents with data representing a display background characteristic or colour, and if the result of the comparison is positive, storing the new pixel data to the frame buffer storage location. If the result of the comparison is negative, a selected data value different from the new pixel data is stored to the frame buffer storage location.