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cod3b453



Joined: 25 Aug 2004
Posts: 619
cod3b453
I got VESA working and am able to write colour data to the screen, but, having specified the linear addressing flag, the screen data is "chopped" into megabyte (2^20 byte) sections allowing me to only write to the top and bottom thrids of my screen at 1024x768x32bpp.

Does this imply a memory limit or does VESA split the memory up?

Any ideas what's going wrong? Embarassed

Thanks,

COD3B453
Post 15 Jul 2006, 17:50
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Mac2004



Joined: 15 Dec 2003
Posts: 313
Mac2004
Are you using real mode or protected mode? From my experience I can say that lfb needs to be accessed from protected mode. Full lfb access doesn't work from real mode nor unreal mode.

regards,
Mac2004


Last edited by Mac2004 on 16 Jul 2006, 19:33; edited 1 time in total
Post 15 Jul 2006, 18:38
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Dex4u



Joined: 08 Feb 2005
Posts: 1601
Location: web
Dex4u
I think you need to implement A20, as i had the same problem years ago, but it was the bottom half that was black, but this was at a smaller size.
If you have enable A20, make sure it works, as some do not work on some PC.
Post 15 Jul 2006, 19:23
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cod3b453



Joined: 25 Aug 2004
Posts: 619
cod3b453
Well it's supposed to be in protected mode... Sad But I don't know how I would test that for sure, other than the fact that it hasn't faulted and hung or rebooted.

Thanks for the tip, Mac2004, I'll check I haven't done something stupid.
Post 15 Jul 2006, 19:31
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cod3b453



Joined: 25 Aug 2004
Posts: 619
cod3b453
Dex4u wrote:
I think you need to implement A20

Shocked I missed your reply when I was writing my last reply...
I'd forgotten to include my a20.inc, but also didn't realise A20 would affect something like that Confused
Thanks, Dex4u! Wink
Post 17 Jul 2006, 19:04
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Dex4u



Joined: 08 Feb 2005
Posts: 1601
Location: web
Dex4u
Your welcome Wink, Oh yes with out A20 enabled, you can only access every other MB.
Post 19 Jul 2006, 00:02
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