Posted By
IstvanV
on 2008-01-11
05:42:27
|  Re: So I want to do plus/4 gfx...
The memory usage is actually slightly less than what would be expected from the size of the generated PRG files, since there is a trivial bug in the converter that makes it save 4K more data than needed. So, the real memory usage is $1001-$E4FF, rather than $1001-$F4FF. That is still much more than the $1001-$B3FF of the original 400 line version, though. Perhaps the best solution would be to allow the selection of any particular size (400, 456, 464, or 496); the memory layout of the FLI data in the larger versions is mostly backward compatible with the smaller ones (the overscanned versions have the data shifted by 24 characters), which makes the implementation easier, and other than limiting the number of lines, the converter would only need to choose from the various display modules. I thought that 464 would be a good default, since it is still NTSC compatible, and has an aspect ratio of about 4:3, which is probably the most common for images.
The YAPE bug is probably related to the manipulation of the internal DMA position counter by FF1E writing tricks. Although it already did not work correctly, since interlaced resolutions are not supported yet by YAPE.
The joystick getting stuck can indeed be annoying. You can avoid this problem by increasing the threshold in the options, or just disabling the use of joystick input if you do not need it anyway. I think it would be possible to prevent the joysticks from being interpreted as key presses in Plus/4 programs by writing the row select value to FD30 only, and #FF to FF08, rather than writing the row select to both registers.
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