Path: utzoo!attcan!uunet!mcsun!unido!fauern!tumuc!lan!roell
From: roell@lan.informatik.tu-muenchen.dbp.de (Thomas Roell)
Newsgroups: comp.windows.x
Subject: Re: VGA X11R4 server problems
Message-ID: <2507@tuminfo1.lan.informatik.tu-muenchen.dbp.de>
Date: 28 May 90 11:37:51 GMT
References: <9692@hydra.gatech.EDU> <1990May24.123603.4257@cti-software.nl>
	<1990May24.225225.1771@jdyx.UUCP>
Sender: news@lan.informatik.tu-muenchen.dbp.de
Organization: Inst. fuer Informatik, Technische Univ. Muenchen, West Germany
Lines: 38
In-reply-to: tpf@jdyx.UUCP's message of 24 May 90 22:52:25 GMT

>The latter has a monochrome monitor attached. On this machine,
>the VGA is not properly returned to text mode after leaving the
>X server; the text font is just gone. This may well be a problem
>with the 386/ix console driver and monochrome VGA monitors,

Am I ask this simple question: Do use Interactives Update X6??? I think all
problems descibed above are gone with that update.

>An interesting X implementation question on 80386 PC's is how to handle
>virtual terminal switches.  I imagine that Esix locks up the virtual
>terminals not becase they don't know how to save and restore the
>graphics display, but because all of the clients remaining active
>while the server sleeps causes too many problems.  Of course the 
>server can't remain active if the VGA is not exposed.

The soltution of this problem is quite simple. Switching the terminals is not
a problem. The real problem is how to prevent the server from writing onto
the screen. When you look at the IBM-code for the VGA you will notice that for
screen-blanking the screen is not physically blanked, but set to black color!!!
Alle routines which drawn physically to the screen are replaced by dummies.
That's the way terminal switch has to bee done.
For the User there will be some surprising effects, cause switching back to
the terminal where he(she) started X will not contain any graphics. The 
graphics will be displayed on the NEXT FREE terminal (confusing, yep ?).

But what for do you need switching to virtual terminals ??? I saw the 
posibility for switch to another terminal from the beginning, but I cann't 
guess who will need such a feature.

- Thomas

--
_______________________________________________________________________________
Thomas Roell             Inst. f. Informatik / Technische Universitaet M"unchen
                         Arcisstr. 21 / 8000 Munich 2 / Fed.Rep. of Germany
E-Mail (domain):	 roell@lan.informatik.tu-muenchen.dbp.de
UUCP (when above fails): roell@tumult.{uucp | informatik.tu-muenchen.de}
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