Video display controller system with attribute latch

摘要

The present invention relates to a video display controller system which permits a variety of differing video attributes for each displayed character. A character code is stored in a character memory and an attribute code is stored in an attribute memory at corresponding memory locations for each display position. In accordance with the present invention the transfer of data to and from the attribute memory is through an attribute latch. Each time a character is written into the character memory the attribute stored in the attribute latch is stored in the corresponding location in the attribute memory. Similarly, the attribute stored in the corresponding location of the attribute memory is stored in the attribute latch upon reading a character from the character memory. The attribute latch can be independently read out or written into. This technique is advantageous for specifying a display screen in which many characters have the same video attribute and for executing block moves within the display screen.