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 DJGPP EGA MEMORY ACCESS 
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Joined: Tue Apr 20, 2010 1:39 pm
Posts: 17
Post DJGPP EGA MEMORY ACCESS
Ok, Ok, its not really OS dev but i thought you might be experienced in protected mode.
I am using an EGA mono card and the memory is at 0xA000:0000 but when i try to access it directly, it segmentation faults.
And if i try to access it with _fpokeb, the computer reboots for no reason.
It is a 486/33 with 12 megs of ram :mrgreen: .


Thu Apr 29, 2010 3:43 pm
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Joined: Sat Jul 25, 2009 7:44 am
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Location: United Kingdom
Post Re: DJGPP EGA MEMORY ACCESS
Have you got a valid GDT?

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Kieran C G Foot


Thu Apr 29, 2010 3:53 pm
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Joined: Tue Apr 20, 2010 1:39 pm
Posts: 17
Post Re: DJGPP EGA MEMORY ACCESS
GDT = Global descriptor table?
Protected mode is setup by a dpmi server so i assume so, but i am a noob in protected mode.


Thu Apr 29, 2010 3:57 pm
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Post Re: DJGPP EGA MEMORY ACCESS
Hmm, i thought you were talking about code compiled in GJGPP, running on a bare pc.

Can you describe the environment?
OS?

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Kieran C G Foot


Thu Apr 29, 2010 4:01 pm
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Post Re: DJGPP EGA MEMORY ACCESS
Its MS-DOS 6.0.


Thu Apr 29, 2010 4:05 pm
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Post Re: DJGPP EGA MEMORY ACCESS
Doesnt MSDOS have an EGA interface or driver???

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Kieran C G Foot


Thu Apr 29, 2010 4:15 pm
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Post Re: DJGPP EGA MEMORY ACCESS
I meant graphics mode ;)


Thu Apr 29, 2010 4:22 pm
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Joined: Sat Jul 25, 2009 7:44 am
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Post Re: DJGPP EGA MEMORY ACCESS
Yeah I know mate, im not sure if direct acces is allowd to that memory???

But i know there are EGA drivers that provide interrupt service for EGA displays...

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Kieran C G Foot


Fri Apr 30, 2010 6:59 am
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Joined: Tue Apr 20, 2010 1:39 pm
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Post Re: DJGPP EGA MEMORY ACCESS
Definitely possible:
http://www.allegro.cc/manual/api/direct ... eo-memory/


Fri Apr 30, 2010 1:34 pm
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Joined: Tue Apr 20, 2010 1:39 pm
Posts: 17
Post Re: DJGPP EGA MEMORY ACCESS
Help?


Sun May 02, 2010 12:25 am
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