Split screen smooth scrolling arrangement

专利名称：Split screen smooth scrolling arrangement发明人：Di Nitto, Robert Salvatore,Porcher, Thomas

Courtenay,Eng, John Wai

申请号：EP84402085.9申请日：19841017公开号：EP0145529B1公开日：19920819

摘要：The present invention is employed in a system which has a bit map memoryconnected to a CRT display device and the CRT display device cab display a fixed regionof information and a scrollable region of information. In a preffered embodiment, thesystem uses a graphic display control circuit (19) to change starting addresses and lengthending values of the fixed and scrollable regions in the bit map memory. By changing thestarting address one scan line per frame, without any actual transfer of data in memory,from one location to another location, the present system effects a «smooth» scroll. Thesystem is able to scroll upward and downward. The system uses logic circuitry to load anoff screen segment of the bit map memory with additional scrollable information, so that(in an upward scroll load) as a top line of the scrollable information region is no longerdisplayed, new information will be displayed at the bottom line of said scrollable region.On the other hand during a downward scroll, a bottom line of information on thescrollable region of the screen will fade out and new information is added, from the offscreen region, of the bit map memory to provide information for a new top line. Inaddition the system has the ability to reorganize the information in the bit map memoryin the event the size or location of the fixed region is to be altered.

申请人：DIGITAL EQUIPMENT CORPORATION

地址：146 MAIN STREET; MAYNARD, MA 01754

代理机构：Mongrédien, André

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