Scrolling display refresh memory address generation apparatus
US4375638A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 16, 1980 |
| Grant date | Mar 1, 1983 |
| Priority date | — |
| Expiry date | Jun 16, 2000 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG09G5/343
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A refresh memory address generation apparatus for a video display controller is disclosed wherein rows of character information stored in a display refresh memory may be relocated without requiring the reconstruction of the display information as stored in the display refresh memory. A roll register and PROMs precoded to perform modular addition and multiplication are used to generate an address used to access the display controller refresh memory such that all but one stationary row of information on the display screen may be scrolled (rolled) up. The scrolling of the information on the display screen is accomplished without requiring movement of the display information in the refresh memory, and the only rewrite of information in the refresh memory is done to blank the one row of information which is vacated.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.