output pixels incorrectly and misalign the Mode 8-9 line. The bug is absent when narrow width playfield is used. If Mode 8 or 9 is NOT using Horizontal scrolling and follows: Mode 2, 3, 4, 5, D, E, or F and HSCROL is , or : then corruption continues through the mode line. Mode 2, 3, 4, 5, D, E, or F and HSCROL is or : then corruption resolves itself within two scan lines. Mode 6, 7, A, B, or C and HSCROL is or : then corruption continues through the mode line. If Mode 8 or 9 is using Horizontal scrolling and follows: Mode 2, 3, 4, 5, D, E, or F: then corruption resolves itself within three scan lines. Mode 6, 7, A, B, or C: then corruption resolves itself within two scan lines. Since the HSCROL values causing the problem are greater than 7, the problem can be averted when Mode 8 or 9 is NOT using Horizontal scrolling by limiting HSCROL shifts to 0 through 7 color clocks and updating the Display List LMS address to horizontally coarse scroll in smaller increments. This strategy resolves all cases in all the Text modes, and all Map modes from A through F which generate 8 or fewer color clocks per byte of screen memory. Hi-Res Last Line Bug A display list should not be built with a hi-res (Mode F) instruction in scan line 247—the last displayable scan line. If the DMACTL Playfield Width bits are not 00 then ANTIC will not generate the vertical sync properly potentially causing display distortion. In any case, this is easy to avoid, since this is not a practical Display List arrangement as this places the Mode line in the overscan area where it is not ordinarily visible. Wide Playfield Horizontal Fine Scrolling The Horizontal Fine Scrolling display list modifier causes ANTIC to fetch extra screen memory corresponding to the next larger Playfield width which provides the data needed to scroll into the display. Since there is no Playfield width larger than the Wide Playfield, ANTIC has no extra data for fine scrolling. ANTIC presents fake data for the area emptied by the shifted screen—on the left side of the display the background color will be shifted in and on the right side a few color clocks of random data will appear at the end of the scrolling range. This pixel