Re: question about system memory space mapping

From: Dirk Wolfgang Glomp (spamtrap_at_crayne.org)
Date: 10/16/04 

Date: Sat, 16 Oct 2004 09:18:56 +0000 (UTC)

Min Wang schrieb:
> Hi Herman,
>
> Thank you very much for the reply.
>
> Several more questions:
> 1) If I have 1M physical memory in my system and I'm using DOS 6.0,
> a0000-bffff of physical memory is disabled and therefore never used/wasted,
> right?

If you write to a0000-bffff(in text-mode3), the graphic ram store the value
and you can read it, to get the value(very slow).
If you set a graphik-mode with clear the screen,
the graphik-ram between a0000-bffff(64KB window) will cleared(other banks too).

I use DOS 6.22(with 512MB) to get in the Big-Real-Mode(max. 4GB data-acess).
So i can use the vesa-bios(vesa.org) of my GF4(VESA3),
to set a video-mode with linear graphic-memory acess.
The linear adress of a VESA-2/3-card, is most mapped in the 4GB.

Dirk