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From: gt8134b@prism.gatech.EDU (Howlin' Bob)
Newsgroups: comp.os.386bsd.development
Subject: Re: Need advice: Which OS to port to?
Message-ID: <107181@hydra.gatech.EDU>
Date: 2 Aug 93 01:56:08 GMT
References: <233o0b$sr9@access.digex.net> <1993Jul28.081737.16319@int-evry.fr> <3390@vall.dsv.su.se> <CB11pL.D12@imag.fr>
Organization: Georgia Institute of Technology
Lines: 37
In <CB11pL.D12@imag.fr> schaefer@imag.imag.fr (Arno Schaefer) writes:
>In article <3390@vall.dsv.su.se>, patrik@dsv.su.se (Patrik Nyblom) writes:
>|> Otherwise Unix/Xenix sounds good, but I'm afraid you have to rewrite your
>|> graphical routines, at least in some ways. Well, bios is the same, but DOS
>|> isn't there.
>Bios is not there. You can't use the Bios in a multitasking environment
>(well, at least that's the case with the disk bios - I am not 100% sure
>about the video bios, but I don't think it's any different).
Actually, I'm using the video BIOS just fine under Linux. All you
need is a little bit of code to support the 386's virtual-8086 mode
and access to a BIOS image (/dev/mem does fine under Linux). Of course,
I wouldn't recommend this sort of thing for real work, but I
wouldn't recommend anything else for a DOS emulator. I decided long
ago that writing video support code for every card was impossible
for a lone author, so running the native BIOS seemed the best way.
I believe the original poster said he wanted total control over the
screen. Both Linux and SVR4 have sufficient console interfaces to
allow direct access to the screen. The mouse is fairly easy, too.
After all, if the X server can do it, any other program can do it.
The main trick is in sharing the screen with other applications (like
the X server) if the console driver supports multiple virtual consoles.
Linux/SVR4 use a handshaking scheme wherein the OS requests that the
application release the console, and notifies the application in control
of the switched-to console (if any) through a signal. It's not pretty,
but it works.
--
Robert Sanders
Georgia Institute of Technology, Atlanta Georgia, 30332
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