HSCROL register. The maximum HSCROL value range covers fine scrolling 16 color clocks from 0 to 15. The color clock information used is buffered from the beginning of the mode line (ANTIC's current memory scan pointer) using enough screen memory bytes to satisfy the 16 color clocks. Horizontal scrolling simply directs ANTIC how many color clocks it can output from the buffered 16 color clocks starting at the last (right most) color clock of the buffered memory. Zero (0) is no color clocks output from the buffer. 1 is the last (right most) color clock of the buffer. The color clocks are inserted at the left edge of the screen, causing the scrolling area of the screen to shift to the right. When the fine scrolling limit is reached, continue scrolling by resetting the HSCROL value and performing a coarse horizontal scroll of the scrolling region. ANTIC's 16 color clock range permits fine scrolling multiple Text Mode characters or more than one byte worth of Map mode pixels. Therefore, the update to the LMS addresses may add or subtract multiple bytes. Alternate Scrolling Methods An interesting use of ANTIC's DMA memory scan behavior permits a strategy for apparently long horizontal scrolling distances, but uses a fraction of the real memory required. As discussed in Horizontal Coarse Scrolling ANTIC's automatic memory scan increment from Mode line to Mode line conflicts with the idea that the rows of screen data are wider than the display. Using memory actually organized as a long, horizontal, contiguous series of bytes requires an LMS modifier for every Display List Text or Map Mode instruction in the scrolling region. Instead of using an LMS modifier for every line this method uses a more "normal" display list that only requires one LMS modifier at the start of the scrolling region. An increment (+1) to the LMS modifier address makes the scrolling region appear to move toward the left. However, the "new" information that has moved into the right side of the scrolling region was previously the first byte on the following line (except for the last byte of the last line — that information had been completely off screen). The second half of this strategy requires the last byte/character of every line in the scrolling region to be updated to show the desired, new information. For a typical scrolling display this would mean updating the last byte of