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VBXE question again


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You can override PF0, 1 and 2. Can't change COLBAK in an attribute list.

Note also there's the bit that allows alternate background colour taken from COLPF3 instead of the attribute value.

And of course the mode inversion bit that allows mixing of hires and multicolour modes.


If the thing is just totally screwed and not properly working then chances are the XDL isn't setup properly or you're not storing to the proper locations in the attribute map.

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its a bitmap overlay...


last bytes of the XDL block is 3,0 so wide screen with priority 0...


and ANTIC displays normal standard Gr.0 screen over it. but the background color and the char color is remaining unchangeable... i can not do a LDA #15 $d017 e.g. to get the lines from back to white? so $d017 seem to be controlled by the VBXE... but with which palette entry? 0 or 1?


same with $d01a/d018...

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Ignore the stuff I posted first up, for some reason I thought you were talking attribute maps.


It's easy to get stuff wrong with the graphic setup, Altirra debug can be of some help.

Charmode or not doesn't matter I don't think - the hires/mutlicolour flip bit should work equally well in both modes.

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Check your XCOLOR bit setting in the VIDEO_CONTROL register. One of the things this changes is how ANTIC hires screens are interpreted for priority, specifically whether the whole screen is PF2 priority like with GTIA or if lit pixels are PF1 priority. For ANTIC text over bitmap graphics you would want XCOLOR=1 so the mode 2 screen is split PF1/PF2, then set overlay priority to be over PF2 and under PF1.


By the way, VBXE's attribute map has a hidden 1-bit bitmap in it separate from the overlay, so you can have three independently scrollable hardware bitmap display layers if you are creative....

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