Apparatus and method for providing a raster-scanned display with converted address signals for VRAM
AssigneeTexas Instruments Incorporated
InventorRichard D. Simpson
Life of this patent
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Abstract
Method and apparatus of providing a display on a raster-scanned screen (1) from data stored in a video random access memory (8) having row and column addresses (6,7) for the storage elements, wherein the display area of the screen (1) is divided into a plurality of identical rectangular areas or "tiles". Addressing of the video random access memory (8) is derived by converting the screen raster-scanning signals via conversion circuits (5) such that sequential addressing of entire rows of storage elements of the video random access memory (8) corresponds to a description of all of the rectangular areas in turn, wherein the number of rectangular areas across the screen width is not equal to an integral power of 2.
Claims9
Display apparatus including
- a display device having a screen,
- scanning circuits for producing a scanning raster on the screen of the display device,
- video random access memory means having an output channel connected to supply data to the display device, and an input channel for data to be stored in the memory means,
- addressing means for addressing the memory means, and
- conversion circuits responsive to signals from the scanning circuits representing the picture elements being scanned to produce address signals for application to the addressing means to cause the memory means to supply the data for the picture element being scanned,
- the conversion circuits being such that sequential addresses of the memory means correspond to sections of the scanning lines of the raster containing an integral power of two of picture elements, the sections forming identical rectangular areas of the screen having a width equal to an integral submultiple of the screen width and a height of an integral power of two of consecutive scanning lines, wherein the width of the identical rectangular areas of the screen is equal to the width of the screen divided by a number other than an integral power of two.
A method of providing a display on a raster-scanned screen from data stored in a video random access memory having row and column addresses for the storage elements in which the display area of the screen is divided into a plurality of identical rectangular areas, each having a height of an integral power of two scanning lines and a width of an integral submultiple of the screen width, said method comprising:
- producing signals representative of picture elements in a scanning raster on the screen;
- converting signals from the scanning raster representative of the picture elements being scanned to produce address signals such that sequential addressing of entire rows of storage elements of the video random access memory corresponds to a description of the whole of each of the rectangular areas in turn, there being a number other than a power of two of the rectangular areas across the screen width;
- and
- addressing the video random access memory based upon the conversion of signals from the scanning raster.
Dependencies are inferred from the claim text.