公开(公告)号：CA2021831A1

公开(公告)日：1991-04-13

申请号：CA2021831

申请日：1990-07-24

Applicant: IBM

Inventor： HARRISON ROY B ,  WOOD ROGER T ,  HAIGH DAVID C

IPC: B41J29/42 ,  B41J2/485 ,  G09G5/22 ,  G09G5/24

Abstract: A display system has, in addition to a display memory for the main storage of display information for a character mode, a separate cache for the temporary storage of the definitions of one or more fonts currently required for display and control logic for updating the font cache from the display memory. This enables the efficient support of a character mode on a display system, particularly where the display memory of that system is implemented with dual-ported memory technology. Compatibility with existing display standards is achieved.

公开(公告)号：CA2021828A1

公开(公告)日：1991-04-13

申请号：CA2021828

申请日：1990-07-24

Applicant: IBM

Inventor： HAIGH DAVID C ,  HARRISON ROY B ,  BONNOR HELEN R

IPC: G09G5/00 ,  G09G5/08 ,  G09G5/39

Abstract: A display system has cursor definition memory for storing data defining a graphics cursor, a cache for the temporary storage of a portion of the graphics cursor for display on a display device, the cache being such that its data rate is sufficient to support the display of the graphics cursor, and control logic for updating the cache from the cursor definition memory at a slower data rate. The cache need only be large enough to store a portion of the cursor at any one time as the graphics cursor is only displayed for a fraction, for example one-tenth, of a scan line and the cache can be updated during the portion of the scan time when the cursor is not displayed. Through the use of a small cache operable at the required data rate, inexpensive memory which does not support the required data rate can be used for the cursor definition memory.