jeepcj2a@fluke.UUCP (Dale Chavdiere) (09/21/84)
I am having trouble with modifying the display list to mix graphics and text modes. Specifically, I have written a slot machine game using the PM Animator software. I poked memory locations used by the display control chip to put some graphics mode 2 lines in a graphics mode 7 field. The program works fine on my 800 using a monitor for display. If I use a normal TV the display rolls vertically. Question; Am I sending too many lines to the display chip? Is there a memory location to control the number of scan lines sent to the display?I believe the monitor just ignores the extra lines.
jhv@houxu.UUCP (James Van Ornum) (09/23/84)
<> The display list itself determines how many scan lines are to be generated. Thus if you modify the display list, you need to redetermine how many scan lines are defined and make adjustments in the list to keep that number to about 216. "Your ATARI Computer" by Ion Poole has a lot of information about customizing the display list. ----------------------- James Van Ornum, AT&T Bell Laboratories, inhp4!houxu!jhv
dan@gloria.UUCP (Dan O'Connell) (10/03/84)
In order to make a custom display list work best on a normal TV, you should have no more than 192 scan lines in total. If you have more than that, rolling may occur on a TV because of the overscan. I can not recall how many scan lines each line of graphics takes, but I think each line of gr.7 is 2 scan lines, and each line of gr.0 is 8 scan lines. Another problem that could cause the rolling on the TV is that if the screen data crosses a 4 K boundry, weird things happen.