Abstract: A system which utilizes two buffers of dual-port memory to seamlessly display video frames on a raster scanned video display device. Dual port memory is organized into two alternate memory banks, each having sufficient capacity to buffer a full frame of video data. As long as the display memory write and read addresses are sufficiently separated by a predetermined number of lines, video data is written and read using alternate banks of memory for each frame. When the write and read addresses are closer than a predetermined number of lines, the video data already stored in a given bank of memory is re-read. After the write and read addresses are again sufficiently separated, video data is again written and read using alternate banks of memory.

Abstract: A system which utilizes dual-port memory to seamlessly display video frames on a raster scanned display device. Dual port memory is partitioned into a ‘single frame buffer’ having sufficient capacity to buffer a full video frame, and an ‘extension buffer’ which is a contiguous extension of the single frame buffer. The two sections together comprise an ‘extended buffer’. As long as the video memory write and read addresses are sufficiently separated by a predetermined number of lines, video data is written and read using the single frame buffer for each frame. When the write and read addresses are closer than a predetermined number of lines, the incoming video data for the next several new frames is written using the ‘extended’ buffer, and also read therefrom. After the write and read addresses are again sufficiently separated, video data is written and read using only the single frame buffer.