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Entering VGA in protected mode

Posted: Sun Aug 31, 2008 11:47 am
by RevivalDBM
Hello,
I was wondering, is it possible to enter VGA in protected mode? I've heard of several methods, including temporarily dropping back to real mode, and running a v8086 task (how would one do that?), are there any other methods, and which do you think would be best?

Re: Entering VGA in protected mode

Posted: Sun Aug 31, 2008 11:56 am
by salil_bhagurkar
'Enter VGA' -- You mean use the VGA functions provided by your BIOS i guess.. Yes it is possible to do that. I drop to real mode and come back in my os (that was when i was making a stupid GUI). But this is a really bad idea if you are using the VGA system frequently.

Optionally you could do what linux does. It sets up the video information and video mode while it is in the real mode at boot time. Using a v8086 task is also feasible. For that you will have to read up on v8086 from the 386 manuals. You can search this post or google for v8086.

Besides you could also directly use the VGA registers to do stuff. Refer to tauron vga utilities (google it)...

Re: Entering VGA in protected mode

Posted: Sun Aug 31, 2008 12:57 pm
by Dex

Re: Entering VGA in protected mode

Posted: Sun Aug 31, 2008 5:20 pm
by Combuster
Try the wiki: VGA Hardware
EDIT: and please use the search function as this question has been asked many times before.

Re: Entering VGA in protected mode

Posted: Mon Sep 01, 2008 12:17 am
by egos
RevivalDBM wrote:which do you think would be best?
I'm programming video directly. It is just necessary to check existng VGA compatible video card and not to use other video drivers, because they may support additional features for vga modes.