Xref:	news2.mv.net comp.os.msdos.djgpp:6173
From:	jb3207 AT eclipse DOT co DOT uk (Jason Barstow)
Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: Any VBE experts out there?
Date:	Fri, 19 Jul 1996 16:34:07 GMT
Organization:	Jabber Interactive
Lines:	46
Message-ID:	<4sodf5$nb1@pub.news.uk.psi.net>
References:	<4s9jq3$3p5 AT status DOT gen DOT nz> <4sa5en$j3l AT status DOT gen DOT nz>
Reply-To:	jb3207 AT eclipse DOT co DOT uk
NNTP-Posting-Host:	callisto-p3.eclipse.co.uk
To:	djgpp AT delorie DOT com
DJ-Gateway:	from newsgroup comp.os.msdos.djgpp

brucef AT central DOT co DOT nz (Bruce Foley) wrote:

>brucef AT central DOT co DOT nz (Bruce Foley) wrote:


>I have discovered (thru experimentation) that the DPMI
>version of 4F07 requires you to pre-cook the values
>stored in cx and dx.  Instead of being x & y coordinates,
>cx is a linear address into a memory bank, and dx is the
>actual memory bank you want to address. (Each
>bank is 64K on my card).
>So, by adding some extra logic to convert screen
>x & y coordinates, I can now continue using
>protected mode banking... Joy!!!

>Bruce.

The official VESA specs say:
(Page 33)

     Note: Function 07h protected mode calls have a different format.
     AX = 4F07h
     BL = 00h Set Display CRTC Start
        = 80h Set Display CRTC Start during Vertical Retrace
     CX = Bits 0-15 of display start address
     DX = Bits 16-31 of display start address

    The protected  mode application must keep track of the color
    depth and  scan line length to calculate the new start address....


**WARNING**
What you are doing presumes 64K banks. For full compatability with all
cards you are supposed to use the full address.

**BUT**
I can't get it to work!
At the moment I too am using the old VBE1.2 int86 version.

So whats the answer? Are the specs wrong?
Anyone know the definitive answer to this?

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