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Convert notes into blockquotes

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James Gregory 2013-12-31 11:06:31 +11:00
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@ -57,9 +57,12 @@ screen start scan line is set—that seems to me to be an advantage—but
because the changed screen can appear *before* the new split screen
start scan line is set.
------------------- ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
![](images/i.jpg) *Remember, the split screen start scan line is spread out over two or three registers. What if the incompletely-changed value matches the current scan line after you've set one register but before you've set the rest? For one frame, you'll see the split screen in a wrong place—possibly a very wrong place—resulting in jumping and flicker.*
------------------- ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
> ![](images/i.jpg)
> Remember, the split screen start scan line is spread out over two or
> three registers. What if the incompletely-changed value matches the
> current scan line after you've set one register but before you've set
> the rest? For one frame, you'll see the split screen in a wrong
> place—possibly a very wrong place—resulting in jumping and flicker.
The solution is simple: Set the split screen start scan line at a time
when it can't possibly match the currently displayed scan line. The easy
@ -103,9 +106,12 @@ designing split-screen images that might be displayed on EGAs, and you
should in any case check how your split-screens look on both VGAs and
EGAs.
------------------- ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
![](images/i.jpg) *I have an important caution here: Don't count on the EGA's split-screen bug; that is, don't rely on the first scan line being doubled when you design your split screens. IBM designed and made the original EGA, but a lot of companies cloned it, and there's no guarantee that all EGA clones copy the bug. It is a certainty, at least, that the VGA didn't copy it.*
------------------- ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
> ![](images/i.jpg)
> I have an important caution here: Don't count on the EGA's split-screen
> bug; that is, don't rely on the first scan line being doubled when you
> design your split screens. IBM designed and made the original EGA, but a
> lot of companies cloned it, and there's no guarantee that all EGA clones
> copy the bug. It is a certainty, at least, that the VGA didn't copy it.
There's another respect in which the EGA is inferior to the VGA when it
comes to the split screen, and that's in the area of panning when the