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Date:      Wed, 13 Aug 1997 12:48:19 +0930 (CST)
From:      Michael Smith <msmith@atrad.adelaide.edu.au>
To:        perlsta@sunyit.edu (Alfred Perlstein)
Cc:        terry@lambert.org, hackers@FreeBSD.ORG
Subject:   Re: reset screen hardware?
Message-ID:  <199708130318.MAA11651@genesis.atrad.adelaide.edu.au>
In-Reply-To: <Pine.BSF.3.96.970808194922.1801A-100000@server.local.sunyit.edu> from Alfred Perlstein at "Aug 8, 97 07:53:06 pm"

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Alfred Perlstein stands accused of saying:
> I don't get it, aren't all SVGA cards the same when i comes down to text
> modes as well as regular VGA modes?

You're right, you don't get it.

No.

> I'm not familiar with the protection mechanism in freebsd, if i wrote a
> program to reset the text screens by programming the ports what kind of
> skeleton code would it need?

It wouldn't work.  You would, in fact, stand a reasonable chance of
producing a program which would be able to destroy utterly older
monitors and many LCD panels.

> Btw, there are interupts that point to tables of data that is put into
> the videocard to set various modes, could the kernel save the data before
> it switches to protected mode?  

Different cards have different register sets.  There is no structure
in a video card BIOS that describes the data and the registers in such
a fashion that you can manipulate them without first knowing what the
card is.

-- 
]] Mike Smith, Software Engineer        msmith@gsoft.com.au             [[
]] Genesis Software                     genesis@gsoft.com.au            [[
]] High-speed data acquisition and      (GSM mobile)     0411-222-496   [[
]] realtime instrument control.         (ph)          +61-8-8267-3493   [[
]] Unix hardware collector.             "Where are your PEZ?" The Tick  [[



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