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Re: Double Lo-Res Broken on the IIe card (Macintosh)?

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On 13/10/2019 12.09, Paul MacMillan wrote:
 > why this difference? I guess in a "real" IIe there are timing
 > differences between the main and aux memories, so the colors appear
 > differently -- and this timing difference may not be there in the
 > IIe card?

In a sense.  If you look at the DGR output of a IIe in monochrome (or 
one of AppleWin's monochrome monitor modes), you'll see that each colour 
is made up of a pattern of monochrome sub-pixels, horizontally.  There 
are 7 of these sub-pixels for for each horizontal DGR pixel (as opposed 
to 14 for single-GR).  Since 7 is an odd number, if you write the same 
value to adjacent DGR pixels, the sub-pixel pattern will in a different 
phase, so it will be interpreted by a colour monitor as a different 
colour.  So it has to be adjusted to be the same colour.  (This is also 
true of DHGR, since only 7 bits per byte are displayed; if you write the 
same value to adjacent screen bytes (aux,main), you'll get a different 
colour pattern.)

I gather that the IIe card software just interprets the DGR colours and 
puts that on the Mac screen, but has a bug in that it fails to interpret 
them differently for the auxmem pixels.  I seem to recall talk of 
patching it.  (I could be talking out my ass for this paragraph, though.)

Given this situation, it would be good if there's a way for a programme 
to tell if it's running on the IIe card, and further to tell if it's 
running with fixed software.

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Thread

Double Lo-Res Broken on the IIe card (Macintosh)? Paul MacMillan <paul.s.macmillan@gmail.com> - 2019-10-13 08:09 -0700
  Double Lo-Res Broken on the IIe card (Macintosh)? Antoine Vignau <antoine.vignau@laposte.net> - 2019-10-13 08:41 -0700
    Re: Double Lo-Res Broken on the IIe card (Macintosh)? Paul MacMillan <paul.s.macmillan@gmail.com> - 2019-10-13 09:13 -0700
      Re: Double Lo-Res Broken on the IIe card (Macintosh)? Paul MacMillan <paul.s.macmillan@gmail.com> - 2019-10-13 10:09 -0700
        Re: Double Lo-Res Broken on the IIe card (Macintosh)? inexorabletash@gmail.com - 2019-10-13 14:11 -0700
        Re: Double Lo-Res Broken on the IIe card (Macintosh)? Brian Patrie <bpatrie@bellsouth.spamisicky.net> - 2019-10-14 02:15 -0500
          Re: Double Lo-Res Broken on the IIe card (Macintosh)? Steve Nickolas <usotsuki@buric.co> - 2019-10-15 15:20 -0400
            Re: Double Lo-Res Broken on the IIe card (Macintosh)? Andy McFadden <thefadden@gmail.com> - 2019-10-15 14:39 -0700
              Re: Double Lo-Res Broken on the IIe card (Macintosh)? MG <mg@zlink.us> - 2019-10-16 11:15 -0700
  Re: Double Lo-Res Broken on the IIe card (Macintosh)? Steve Nickolas <usotsuki@buric.co> - 2019-10-13 19:33 -0400

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