[hatari-devel] New support for STE's 224 bytes overscan

Anders Eriksson ae at dhs.nu
Mon Dec 7 20:20:07 CET 2009


On Mon, 7 Dec 2009, npomarede at corp.free.fr wrote:

> this is strange, the non working screens are now ok for me (for example
> the picture asking to insert disk 2 in MOLZ).

Hi!

Strange. But ok let's forget that now and assume the version my friend 
compiled did not contain your fixes. I'll ask him later if he can make 
another try.


> You mean on STE the screen is shifted to the left (not to the right) ?
> Else I don't understand how the far right pixels would be more visible.

Phu, how should I explain this..

I mean that the STe 224 byte overscan is shifted to the right, look at 
this picture I threw together:

http://ae.dhs.nu/pics/overscans.jpg

The pictures are taken with a PAL capture machine from a real STe output.


> How do you count 416 pixels ? 224 bytes would give 448 pixels, and as the
> first 16 are background ones, this would leave 432. Do you count only
> usable pixels ? (I count 8 pixels per bytes, even if the hi/lo switch are
> sometimes adding some black bars or things like that).

Yes I count usable pixels, and as my understanding have always been that 
the traditional 230 byte overscan makes 416 usable pixels. Then when 
comparing to the 224 byte overscan, the same amount of usable pixels are 
available (look at the picture linked to above, you'll see that what the 
224 byte overscan misses at the left, it gains at the right).

There might be a misunderstanding though - that there in fact are not 416 
usable pixels on a 230 byte overscan line, then my calculations are not 
correct, but I also wonder why Hatari would then display graphics that are 
not displayed correct on a real ST/e.

> But on real ST, you wouldn't change the color outside the visible area,
> or you wouldn't see the colors there too. Do you mean something that would
> use Hatari in a way a nomal ST can't be used ?

Yes! As I said, for _coding_ fullscreens, plasmas etc, not watching them 
:)

--
Anders Eriksson
ae at dhs.nu     http://www.dhs.nu/
ae at atari.org  http://www.atari.org/



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